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SECTION 10 CONCRETE STRUCTURES
S10.01 Concrete
S10.01 (1) Description
(a) Scope
This work shall consist of the general items pertaining to the required class or classes of concrete, with or without reinforcement, constructed in accordance with these Specifications and the lines, levels, grades and dimensions shown on the Drawings, and as required by the Engineer.
Portland cement concrete shall consist of a mixture of cement, water and coarse and fine aggregates.
(b) Concrete Classes and their Use
The use of each class of concrete shall be as follows unless otherwise shown on the Drawings or directed by the Engineer:
|
CLASS |
USE OF EACH CLASS OF CONCRETE |
STRENGTH* kg/cm2 |
|
| A – 1 | - | Cast-in-place prestressed concrete box girders for cantilever erection |
400 |
| A – 2 | - | Cast-in-place prestressed concrete box girder. |
400 |
| A – 3 | - | Pre-cast prestressed concrete I-girders. |
400 |
|
|
|||
| B – 1 | - | (not applicable) |
350 |
|
|
|||
| C – 1 | - | Reinforced concrete deck slabs, diaphragms of prestressed concrete I-Girders and parapet and foundations of lighting poles excluding those for RC hollow slab. |
290 |
| C – 2 | - | Pre-cast reinforced concrete plate. |
290 |
| C – 3 | - | Pre-cast reinforced concrete piles. |
290 |
| C – 4 | - | RC piers (including cantilevered pier heads, pier columns and footings), RC abutments (including wing walls), RC retaining walls and box culverts. |
290 |
| C – 5 | - | RC hollow slab and parapet and foundation of lighting poles for RC hollow slab. |
290 |
|
|
|||
| D – 1 | - | (not applicable) |
240 |
|
|
|||
| E – 1 | - | Approach slabs. |
210 |
| E – 2 | - | Pipe culverts. |
210 |
| E – 3 | - | Concrete foundation and encasement of RC pipes. |
210 |
| E – 4 | - | Precast concrete curbs. |
210 |
|
|
|||
| G | - | Lean Concrete and Levelling concrete |
- |
|
|
|||
| P | - | Concrete pavement (28 days flexural strength) |
45 |
|
|
|||
| Y | - | Cast-in-place reinforced concrete piles. |
290 |
*Note: Minimum 28-day compressive strength by cylinder test (30cm x Φ15cm) except Concrete Class P.
(c) Determining the Proportions and Batch Weights
No structural concrete shall be placed in the Works until the relevant mix has been approved by the Engineer.
The proportions and batch weights for concrete will be determined as prescribed below. The determinations will be made after the materials furnished by the Contractor have been accepted.
(i) Trial mixes – The Contractor shall, at least thirty five (35) days prior to the commencement of concreting, have laboratory trial mixes prepared which shall be witnessed by the Engineer.
The laboratory trial mixes shall be so designed by the Contractor that the resultant compressive or flexural strength result as applicable, (Preliminary Test Result), shall show an adequate working strength margin, in accordance with normal good practice, so that the probability of site working strength test values falling below the minimum specified strength shown in Table 10-1-1 is reduced to a value not exceeding 5%.
The Engineer will determine the proportions on the basis of the trial mixes conducted with the materials to be used in the Work.
The proportions for the trial mixes will be based on the values given in Table 10-1-1 adjusted as described in this sub-clause. However the proportions given in the table are approximate values for the convenience of the Contractor’s estimate only, excepting that it shall be understood that:
- The water cement ratios given shall be absolute maximum values
- The cement contents given shall be absolute minimum values
- The minimum compressive strength values given shall be taken to mean the minimum site working strength.
Table 10-1-1 Standard Proportions of Concrete for Use in Structures
|
STRENGTH CLASS 1/ DESCRIPTION |
A-1 A-2 A-3 |
B-1 |
C-1 C-2 C-3 C-4 C-5 |
D1
|
E-1 E-2 E-3 E-4 |
F |
G
|
Y |
P |
| Maximum sizeof coarseAggregate (mm) |
20 |
20 |
20 |
20 |
20 |
25 |
40 |
20 |
25 |
|
Slump (cm) 2/ |
7.5+ 2.5 |
7.5+ 2.5 |
7.5+ 2.5 |
7.5+ 2.5 |
7.5+ 2.5 |
5.0+ 2.5 |
5.0+ 2.5 |
18.0+ 2.5 |
Max. 5 |
|
Maximum Water/cement ratio W/C (%) |
37.5 |
42.9 |
49.4 |
56.9 |
61,4 |
76.0 |
88.2 |
49.4 |
40.0 |
|
Water content W (kg/m3) |
170 |
175 |
181 |
181 |
181 |
169 |
157 |
197 |
160 |
|
Cement content C (kg/m3) |
450 |
408 |
366 |
318 |
295 |
222 |
178 |
399 |
400 |
|
Fine aggregate S (kg/m3) |
720 |
765 |
819 |
860 |
885 |
906 |
896 |
786 |
791 |
|
Coarse aggregate G (kg/m3) |
1100 |
1075 |
1044 |
1041 |
1039 |
1110 |
1187 |
1004 |
1077 |
|
Minimum 28 day compressive strength by cylinder test (30 x Ø15(cm) (kg/cm2) 3/ 4/ |
400 |
350 |
290 |
240 |
210 |
130 |
- |
290 |
-
|
|
Minimum 28 day flexural strength (kg/cm2) 5/ |
- |
- |
- |
- |
-
|
- |
- |
- |
45 |
Notes to Table 10-1-1
1/ Class of concrete shall be applied as shown in Clause S10.01(1)(b).
2/ Slump will be determined in accordance with AASHTO T119 or JIS A 1101.
3/ Concrete compressive tests shall conform to the requirements of AASHTO T22 and 23.
4/ In the event of any dispute regarding conformance with this Specification, the results obtained by the standard cylinder test (30cm x φ15cm) will be taken as conclusive.
5/ Flexural strength will be tested by the third point loading method in accordance with AASHTO T97.
The weights of aggregate per cubic metre of concrete in Table 10-1-1 are based on the use of aggregates which have a bulk specific gravity of 2.65 when in a saturated surface-dry condition, the use of uniformly graded natural sand having a fineness modulus of 2.75, and the use of a uniformly graded coarse aggregate of the size indicated.
For aggregates having other specific gravities, the weights will be corrected by multiplying the weights shown in the table by the specific gravity and dividing by 2.65.
When angular, manufactured sand or sand having a fineness modulus greater than 2.75 is used, the amount of fine aggregate will be increased and the amount of coarse aggregate decreased. When using sand having a fineness modulus less than 2.75, the amount of fine aggregate will be decreased and the amount of coarse aggregate increased. For each change in fineness modulus of 0.10 as compared to 2.70, the percentage of sand will be changed by 1 percent in relation to the total weight of combined fine and coarse aggregates. The fineness modulus of fine aggregate will be determined by adding the cumulative percentage, by weight, of material retained on each of ASTM Standard sieves 9.5, 4.75, 2.36, 1.18, 0.600, 0.300 and 0.150 mm, and dividing by 100.
The correction for fineness modulus will be made prior to making a correction in the weights of Table 10-1-1 for variations from 2.65 in specific gravity.
The Contractor may, subject to prior approval by the Engineer, use alternative sizes of coarse aggregate to those in Table 10-1-1.
If the use of an alternative size of coarse aggregate produces concrete, which exceeds the permissible water content, thereby requiring additional cement above that specified, no compensation will be made to the Contractor for the additional cement. Designated sizes of coarse aggregate need not be separated into component sizes. However, two sizes are preferred when the maximum size exceeds 2.5 cm. If one or more of the component sizes used fails to meet the specified grading for its respective size, but a combination of the sizes can be used to meet the specified grading for the combined size, they may be used with the written permission of the Engineer.
(ii) Proportions and batch weights – The Engineer will designate the weight in kilograms of fine and coarse aggregate (in a saturated surface-dry condition) per cubic metre of concrete for the specified class of concrete and these proportions will not be changed except as provided in the paragraphs immediately following. In addition, the Engineer will also designate the batch weights of aggregate after he has made moisture determinations and corrected the saturated surface-dry weights for free moisture.
In batching aggregate for structures containing less than 25 cubic metres of concrete, the Contractor may substitute approved volumetric measuring devices in lieu of weighing devices. In such event, weighing will not be required but the volumes of coarse aggregate and of fine aggregate measured into each batch shall be those designated by the Engineer.
(iii) Adjustment for variation in workability – If it is found impossible to obtain concrete of the desired workability with the proportions originally designated by the Engineer, he will make such changes in aggregate weights as are necessary, provided that in no case shall the cement content originally designated be changed.
(iv) Adjustment for variation in yield – If the cement content of the concrete, determined by means of the yield test, AASHTO T 121, varies more than plus or minus two (2) percent from the designated value in Table 10-1-1, the proportions will be adjusted by the Engineer to maintain a cement content within these limits. The water content shall in no case exceed the specified amount.
(v) Adjustment for excess water content – If, when using the designated cement content, it is impossible to produce concrete having the required consistency without exceeding the maximum allowable water content specified in Table 10-1-1, the cement shall be increased by the Engineer so that the maximum water content will not be exceeded.
(vi) Adjustment for new materials – No change in the source or character of the materials shall be made without due notice to the Engineer and no new materials shall be used until the Engineer has accepted such materials and has designated new proportions based on tests or trial mixes as provided herein. Should the changes due to the new materials require an increase in the amount of cement, no additional payment shall be made to the Contractor for the cost of such additional cement.
(d) sampling of Concrete
In order to asses compliance of concrete during construction, the Contractor shall prepare and cure test specimens which shall be tested at 7 days and 28 days as determined by the Engineer, or at any other interval that may be deemed necessary to determine the strength of concrete. (Site Working Strength).
(i) Specimens shall be made in pairs as follows:
a) For batches Individual Pours < 1 m3
Not more than one sample shall be taken from which not less than 2 specimens shall be tested.
For batches > 1 m3 < 20 m3
Not more than two samples shall be taken from which not less than 4 specimens shall be tested.
b) Continuous Pours
For any given section of the work that does not qualify as bulk concrete i.e. > 20 m3 < 100 m3
A minimum of three random samples shall be taken from which not less than 6 specimens shall be tested.
For any given section of the work that is considered as bulk concrete i.e. > 100 m3
A minimum of four random samples shall be taken for every 100 m3 of concrete or fraction thereof greater than 100 m3 placed during one days work or as deemed necessary by the Engineer from which not less than eight specimens shall be tested.
(ii) Irrespective of the quantity, every days production of concrete shall be tested both for strength and for slump and every structure and every component of every structure shall likewise be so tested for strength and for slump. The checking and testing of the concrete shall be the prerogative of the Engineer, and he may increase the specified strength and condition as required for the project.
The concrete test specimens will be tested by the Contractor at a conveniently located and properly equipped laboratory.
The Contractor shall take, on his own responsibility, every precaution to prevent injury to the test specimens during handling, transporting and storing.
(e) Strength Requirements
(i) Specimen Preparation
The ultimate compressive strength of the concrete shall be determined on specimens obtained and prepared in accordance with AASHTO T141 (ASTM C 172) and AASHTO T23 (ASTM C 31). Test cylinders made in the laboratory shall conform to AASHTO T126 (ASTM C 192).
The compression test performed on cylinders shall be according to specifications AASHTO T22 (ASTM C 39).
(ii) Compressive and Flexural Strength
The average site working strength value of any 4 consecutive results of the 28 day tests shall not be less than the minimum strength specified in Table 10-1-1 for the respective class of concrete. In the event of failure to comply with this requirement all of the concrete in all the batches represented by such samples and specimens, including any batches within the sequence, which were not sampled, shall be deemed not to comply with the strength requirement of this clause.
If at any time the average of any 4 consecutive results of 7 day tests falls below 70% of the prescribed minimum value at 28 days for compressive strength or below 80% of the prescribed minimum value at 28 days for flexural strength the cement content of the concrete will be increased by at least 20 kg per cubic metre of compacted concrete, without extra payment, until any necessary mix modifications have been agreed following examination of 28 day tests.
(iii) Characteristic Strength
The characteristic strength of the various classes of concrete shall be determined as soon as the first 30 test results of each class become available.
(iv) Failure to Comply with Compressive Strength Requirements
In the event of compressive strength results not complying with the strength requirements of this Clause or in the event of doubtful results, the Engineer will proceed to check the sample compressive strength by means of compressive tests performed on test specimens taken with a rotary core borer at suitable points indicated by the Engineer on the structure already constructed.
Such tests shall be carried out by an agreed authority having suitable test facilities. If such tests show strength in compliance with the requirements herein specified, the concrete will be considered satisfactory. If such tests do not comply with the requirements, the Engineer may direct the Contractor to cut out and make good the defective work at the Contractor’s expense.
(v) Care of Specimens
The cost of taking specimens and performing the tests including the cost of providing stout, substantial packing cases and the cost of shipping or transporting the test specimens from the site to the laboratory shall be included as part of the price bid for Portland cement concrete. The Contractor shall take, on his own responsibility, every precaution to prevent injury to the test specimens during handling and transporting.
(vi) Records
The records of all tests shall be kept by the Engineer but results shall be available at all times to the Contractor. The Contractor shall be responsible for making such adjustments, as may be necessary to produce specification concrete and the test results shall include whether or not the concrete is satisfactory.
S10.01 (2) Materials
(a) General
All materials to be furnished and used that are not covered in this section shall conform to the requirements stipulated in other applicable sections.
(b) Cement
Unless specified to the contrary or otherwise permitted by the Engineer the Contractor shall use only one brand of any one type of cement having uniform quality for the Work. All cement used in the Work shall be ordinary Portland Cement (ASTM Type-I) conforming to the minimum requirements of JIS R 5210, AASHTO-M 85, BS 12: 1978 or TCVN 2682 – 1992 for PC-40 Cement.
(c) Admixtures
Admixtures shall not be used without the written approval of the Engineer. The Contractor shall submit samples of any proposed admixtures to the Engineer at least 28 days prior to the date of commencement of construction of the particular structure or portion of structure on which he intends to use such admixtures.
(d) Water
All water used in concrete shall be subject to the Engineer’s approval. Water used in mixing, curing, or other designated applications shall, as a general rule be potable, otherwise reasonably clean and free from oil, salt, acid, alkali, sugar, vegetable, or any other substance injurious to the finished product. If required by the Engineer, water shall be tested by comparison with distilled water. Comparison shall be made by means of standard cement test for soundness, time of setting and mortar strength. Indication of unsoundness, change in time of setting of plus or minus 30 minutes or more, or decrease of mortar strength more than 10 percent compared with distilled water shall be sufficient cause for rejection of the water that is being tested.
Where the source of water is relatively shallow, the intake shall be so enclosed as to exclude silt, mud, grass, or other foreign materials.
(e) Fine Aggregate
(i) The fine aggregate for concrete shall consist of natural sand or, subject to approval of the Engineer, other inert materials with similar characteristics, having clean, hard and durable particles, and it shall be free from objectionable quantities of dust, silt, clay, organic matter, and other impurities.
(ii) The fine aggregate shall be uniformly graded and shall meet the following grading requirements:
Grading of Fine Aggregate:
|
Sieve Size (mm) |
Cumulative Passing Percentage by Weight |
|
9.5 4.75 2.36 1.18 0.600 0.300 0.150 |
100 95 – 100 80 – 100 50 – 85 25 – 60 10 – 30 2 – 10 |
Sieve analysis of fine aggregate shall be made in accordance with JIS A 1102 (Method of Test for Sieve Analysis of Aggregate) or AASHTO – T 27.
The gradation requirements given above are the extreme limits to be used in determining the suitability of material from all possible sources of supply. The gradation of materials from any one source shall not vary in composition beyond the range of values that govern the selection of a source of supply. For the purpose of determining the degree of uniformity, a fineness modulus determination shall be made upon representative samples, submitted by the Contractor, from such sources as he proposes to use. If fineness modulus of fine aggregate varies more than 0.2 from the value used in selecting concrete proportions, the fine aggregate shall be rejected unless suitable adjustment of the mix proportions are made with the approval of the Engineer.
(iii) The amount of deleterious substances in fine aggregate shall not exceed the limits specified in Table 10-1-2. Treatment of other deleterious substances, which are not shown in the above table, shall be determined by the direction of the Engineer. Tests for material finer than 0.075 mm sieve shall be made in accordance with JIS A 1103 (Method of Test for Amount of Material Passing Standard Sieve 0.074 mm in Aggregates), or AASHTO – T 11.
Table10-1-2
Limits for Deleterious Substances in Fine Aggregates
|
Item |
Maximum % by Weight |
| * Clay lumps* Material finer than 0.075 mm sieve: Concrete subject to abrasion All other concrete* Material coarser than 0.300 mm
sieve floating on a liquid having a Specific gravity of 1.95 |
1.0
3.0 1/ 5.0 1/
0.5 2/ |
Note:
1/ In the case of crushed aggregate, if the material finer than 0.075 mm sieve consists of the dust of fracture essentially free from clay or shale, these percentages may be increased to 5 and 7 percent respectively.
2/ This requirement does not apply to manufactured sand produced from blast furnace slag.
(iv) All fine aggregate shall be free from injurious amounts of organic impurities. Approximate determination of the presence of injurious organic impurities in natural sand shall be in accordance with JIS A 1105 (Method of Test for Organic Impurities in Sands) or AASHTO T 21. Aggregate subjected to the colourimetric test for organic impurities, and producing a colour darker than the standard, shall be rejected.
However, any sand that fails to meet the above requirement may be used provided that the compressive strength of mortar specimens using such sand is more than 95% of that of mortar specimens using the same sand, which is washed by 3% solution of sodium hydroxide and then by water, and approved by the Engineer. Testing age of mortar specimens shall be 7 and 28 days for normal Portland cement.
Compressive strength of mortar specimens shall be determined by AASHTO T 71, “Effect of Organic Impurities in Fine Aggregate on Strength of Mortar”.
(f) Coarse Aggregate
(i) The coarse aggregate shall consist of one or more of the following: crushed stone, gravel, blast-furnace slag, or other approved inert materials of similar characteristics having clean, hard, durable pieces. It shall be free from objectionable quantities of flat or elongated particles, organic matter or other deleterious matter.
(ii) Sieve analysis of coarse aggregate shall be made in accordance with JIS A 1102 (Method of Test for Sieve Analysis of Aggregate) or AASHTO T 27 and material shall meet the following grading requirements:
Grading of Coarse Aggregate
| SIZE OF |
PERCENTAGE BY WEIGHT (JIS A 1102) |
||||||||||||
| COARSE |
AMOUNTS FINER THAN EACH STANDARD SEIVE (mm) |
||||||||||||
| Agg -mm | 100 | 80 | 60 | 50 | 40 | 25 | 20 | 15 | 10 | 5 | 2.5 | ||
| 50 | - | 5 | - | - | 100 | 95-100 | - | 37-70 | - | 10-35 | - | 0-5 | - |
| 40 | - | 5 | - | - | - | 100 | 95-100 | - | 35-70 | - | 10-30 | 0-5 | - |
| 25 | - | 5 | - | - | - | - | 100 | 95-100 | - | 30-70 | - | 0-10 | 0-5 |
| 20 | - | 5 | - | - | - | - | - | 100 | 90-100 | - | 20-55 | 0-10 | 0-5 |
| 15 | - | 5 | - | - | - | - | - | - | 100 | 90-100 | 40-70 | 0-15 | 0-5 |
| 80 | - | 40 | 100 | 90-100 | 45-75 | - | 0-15 | - | 0-5 | - | - | - | - |
| 60 | - | 40 | - | 100 | 90-100 | 35-70 | 0-15 | - | 0-5 | - | - | - | - |
| 50 | - | 25 | - | - | 100 | 90-100 | 35-70 | 0-15 | - | 0-5 | - | - | - |
| 40 | - | 20 | - | - | - | 100 | 90-100 | 20-55 | 0-15 | - | 0-5 | - | - |
(iii) The amount of deleterious substance in coarse aggregate shall not exceed the limits prescribed in Table 10-1-3. Treatment of the other deleterious substances, which are not shown in the table, shall be determined by the direction of the Engineer.
Table 10-1-3 Limits of Deleterious Substance (Percent by Weight) in Coarse Aggregate
|
Item |
Maximum |
| Clay lumpsSoft particlesMaterial finer than 0.075 mm sieveMaterial floating on a liquid having a specific gravity of 1.95 | 0.25 5.0
1.0 1/ 1.0 2/ |
Note:
1/ In the case of crushed aggregate, if the material finer than 0.075 mm sieve consists of the dust of fracture essentially free from clay or shale, this percentage may be increased to 1.5.
2/ This requirement does not apply to manufactured sand produced from blast furnace slag.
(iv) Test for material finer than 0.075 mm sieve shall be made in accordance with JIS A 1103 (Method of Test for Amount of Material Passing Standard Sieve 0.075 mm in Aggregates), or AASHTO T11. Test for soft particles shall be made in accordance with JIS A 1126 (Method of Test for Soft Particles in Coarse Aggregate by Use of Scratch Tester), or AASHTO T 112.
(g) Test of Aggregate
Before use, results of the foregoing tests of aggregate from each source shall be submitted to and approved by the Engineer. Coarse aggregate shall meet the requirements ASTM C39 for compressive strength and the percentage of wear of the aggregate shall not be greater than 50 as determined by AASHTO T96. Tests for aggregate in use shall be made when required by the Engineer.
(h) Expansion Joint Filler (Asphaltic Joint Filler)
Expansion joint filler shall conform to the requirements of AASHTO M 33.
The filler for each joint shall be furnished in a single piece for the full depth and width required for the joint unless otherwise authorized by the Engineer. When the use of more than one piece is authorized for a joint, the abutting ends shall be fastened securely, and held accurately to shape, by stapling or other positive fastening satisfactory to the Engineer.
(i) Storage of Materials
(i) Storage of cement – Cement may be shipped from pre-tested and approved bins at the mill. Cement shall be stored in a damp-proof warehouse with a floor raised at least 30 cm from the ground so as to permit easy access for inspection and for use in the delivered order. Bagged cement shall not be piled more than 13 sacks high. Cement, which has become damp, lumpy or otherwise not in proper condition, shall not be used. Cement stored by the Contractor for a period longer than 60 (sixty) days shall require the Engineer’s approval before being used on the work.
(ii) Storage of aggregate – Fine and coarse aggregates shall be stored separately to prevent contamination by foreign material. Aggregate shall be stored in such a manner as to keep the moisture content as uniform as possible, and shall be handled in such a manner as to prevent segregation. Aggregate shall be stored so as to protect it from the direct rays of the sun. Aggregate from different sources of supply shall not be stored in the same place without permission from the Engineer.
S10.01 (3) Equipment and Tools
Equipment and tools necessary for handling materials and performing the work, and satisfactory to the Engineer as to design, capacity, and mechanical condition, shall be at the site of the work before work is started.
If any equipment is not maintained in full working order or if the equipment as used by the Contractor proves inadequate to obtain the results prescribed, such equipment shall be improved or other satisfactory equipment substituted or added at the direction of the Engineer.
(a) Batching Plant and Equipment
(i) General – All material in the mix shall be proportioned wholly by weight. The batching plant shall include bins, weighing hoppers and scales for the fine aggregate and for each separated size of coarse aggregate. If cement is used in bulk, a bin, hopper and scales for the cement shall be included. The container shall be watertight. Provision satisfactory to the Engineer shall be made for batching other components of the mix at the batching plant, which may be either stationary or mobile type. It shall be always properly levelled within the accuracy required for the proper operation of weighing mechanisms.
(ii) Bins and hoppers – Bins with adequate separate compartments for fine aggregate and for each required size of coarse aggregate shall be provided in the batching plant. Each compartment shall discharge efficiently and freely into the weighing hopper. Means of control shall be provided so that as the quantity desired in the weighing hopper is being approached, the material may be added slowly and shut off with precision. A port or other opening for removing any overload of the several materials from the hopper shall be provided. Weighing hopper shall be constructed so as to discharge completely.
(iii) Scales – The scales for weighing aggregates and cement shall be of either the beam type or the spring-less dial type. They shall be accurate within one-half of 1% under operating conditions throughout the range of use. Ten weights of 25 kilograms each shall be available for checking accuracy. All exposed fulcrums, clevises and similar working parts of scales shall be kept clean. When beam-type scales are used, provision shall be made for indicating to the operator that the required load in the weighing hopper is being approached. The device shall indicate at least the last 100 kilograms of load and up to 25 kilograms overload.
All weighing and indicating devices shall be in full view of the operator while charging the hopper and he shall have convenient access to all controls.
Cement may be measured by weight, or in standard sacks considered to weigh 50 kilograms net. When measured by weight a separate, satisfactory scale and hopper shall be provided together with a boot or other approved device to transfer the cement from the weighing hopper. Satisfactory methods of handling shall be employed.
Batching shall be so conducted as to result in the weights of material required, within tolerances of 1% for cement and 2% for aggregates.
(b) Mixers
(i) General – All concrete shall be mixed in batch mixers. It may be mixed at the site of construction, at a central plant, or in transit.
Each mixer shall have attached to it in a prominent place a manufacturer’s plate showing the capacity of the drum in terms of volume of mixed concrete and the speed of rotation of mixing drum.
(ii) Mixers at site of construction – Mixers at the site shall be approved drum-type capable of combining the aggregate, cement and water into a thoroughly mixed and uniform mass within the specified mixing period and of discharging the mixture without segregation. The mixer shall be equipped with a suitable charging hopper, water storage, and a water-measuring device, accurate within 1%. Controls shall be so arranged that the water can be applied only while the mixer is being charged. The discharge level shall lock automatically until the batch has been mixed the required time after all materials are in the mixer.
Suitable equipment for discharging the concrete on the roadbed shall be provided. The mixer shall be cleaned at suitable intervals. The pick-up and throw-over blades in the drum shall be replaced when they have lost 10% of their depth.
(iii) Central plant mixers – These mixers shall be of approved drum type capable of combining the aggregate, cement and water into the thoroughly mixed and uniform mass within the specified mixing period and of discharging the mixture without segregation. Central plant mixers shall be equipped with an acceptable timing device that will not permit the batch to be discharged until the specified mixing time has elapsed. The water system for a central mixer shall be either a calibrated measuring tank or a metre and shall not necessarily be an integral part of the mixer.
The mixers shall be cleaned at suitable intervals. They shall be examined daily for changes in interior condition. The pick-up and throw-over blades in the drum shall be replaced when they have lost 10% of their depth.
(iv) Truck or transit mixers – These shall be equipped with electrically actuated counters by which the number of revolutions of the drum or blades may readily be verified and the counters shall be actuated at the commencement of mixing operations at designated mixing speeds. The mixer when loaded shall not be filled to more than 60% of the drum gross volume. The mixer shall be capable of combining the ingredients of the concrete into a thoroughly mixed and uniform mass and of discharging the concrete with a satisfactory degree of uniformity.
Except when intended for use exclusively as agitators, truck mixers shall be provided with a water-measuring device to measure accurately the quantity of water for each batch. The delivered amount of water shall be within plus or minus 1% of the indicated amount.
(c) Vibrators
Unless otherwise directed, the concrete shall be consolidated with approved mechanical vibrators operating within the concrete. When required, vibrating shall be supplemented by hand spading with suitable tools to assure proper and adequate compaction.
The vibrators shall be of a type approved by the Engineer, with a minimum frequency of 3500 impulses per minute and shall be capable of visibly affecting a properly designed concrete with a 2 centimetre slump over a circular area of 45 centimetres radius. The number of vibrators used shall be sufficient to consolidate the concrete properly within 10 minutes after it is deposited in the forms and in addition at least 3 spare vibrators shall be available on standby at the site of the pour to maintain immediate continuity in case of breakdown.
(d) Forms
(i) Forms shall be made of metal, shall conform to the shape, lines and dimensions of the members shown on the Drawings, and shall be so constructed as to prevent deformation due to load, vibration, and other causes.
(ii) Forms shall be properly equipped with braces, ties and other devices, so as to maintain them in the positions and the shape as shown on the Drawings.
(iii) Forms shall be so constructed that they can be removed easily and safely. Joints in linings or panels shall be either horizontal or vertical as far as possible, and shall be sufficiently tight to prevent any leakage of mortar.
(iv) Curved forms shall be of the radius called for on the Drawings and acceptable flexible forms shall be installed with that radius.
(v) After forms have been set in the correct location, they shall be inspected and approved by the Engineer before concrete is placed.
(vi) Care shall be exercised to keep forms free from dust, grease or other foreign matter. No material or treatment that will adhere to concrete or discolour concrete shall be used. All forms shall be treated with an approved form-release-oil prior to placing reinforcement.
(vii) For narrow walls, columns, etc., where the bottom of the form is inaccessible, lower form boards or parts thereof shall be left loose so that they may be removed for cleaning out extraneous material immediately before placing concrete.
(viii) Forms for exposed surfaces shall be constructed with triangular fillets not less than 25 mm x 25 mm attached so as to prevent mortar runs and to produce smooth straight chamfers at all sharp external edges of the concrete.
(e) Batching and Transporting Materials
For mixing at site of construction, aggregates shall be transported from the batching plant to the mixer in batch boxes, vehicle bodies, or other containers adequate in design and construction to properly carry the batch required. Partitions separating batches shall be adequate and effective to prevent spilling from one compartment to another while in transit or while being dumped.
Cement in original shipping containers may be transported on top of the aggregates. The number of sacks of cement required for each batch shall be placed on the aggregates for that batch. Sacked cement shall be emptied into the aggregates prior to dumping into mixer.
Batches shall be delivered to the mixer separately and intact. Each batch container shall be dumped cleanly into the mixer without loss of cement or mixing or spilling of material from one batch compartment into another.
(f) Mixing Concrete
(i) General – Concrete shall be mixed at the construction site, at a central mixing plant, in a truck mixer, or by a combination of central plant and truck mixing. Hand-mixing may be used only when approved by the Engineer. No concrete shall be mixed, placed, or finished when the natural light is insufficient, unless an adequate and approved artificial lighting system is operated.
(ii) Mixing at site of concrete construction – Concrete shall be mixed in a batch mixer of the type and capacity approved by the Engineer. Mixing time shall be determined by the Engineer in accordance with JIS A 1119 (Method of Test for Variation in Unit Weight of Air Free Mortar in Freshly Mixed Concrete). When results of the above tests are not available, the mixing time shall be longer than 1 1/2 minutes after all the materials have been introduced into the mixer, but in no case shall the mixing time exceed three times the mixing time prescribed above. Charging of water into the mixer shall begin before the cement and aggregates enter the drum. During mixing, the drum shall be operated at speeds specified by manufacturers. Pick-up blades in the drum of the mixer, which are worn down 2 cm or more at any part, must be replaced.
The volume of a batch shall not exceed the manufacturer’s rated capacity of the mixer without written permission of the Engineer. No mixer whose rated capacity is less than a one-bag batch shall be used.
Concrete shall be mixed only in such quantities as are required for immediate use, and concrete which is not of the required consistency at the time of placement shall not be used.
Re-tempering of concrete will not be permitted. Entire content of the mixer shall be removed from the drum before materials for the next batch are placed therein. Upon cessation of mixing for a considerable length of time, the mixer shall be cleaned thoroughly. Upon resumption of mixing, the first batch of concrete material placed in the mixer shall contain sufficient sand, cement, and water to coat the inside surface of the drum without diminishing the required mortar content of the mix.
(iii) Central plant mixing – When mixed at a central plant, the mixer and methods used shall be in accordance with the requirements of Sub-clause S10.01 (3) (f) (ii). Mixed concrete shall be transported from the central mixing plant to the site of work in agitator or non-agitator trucks approved by the Engineer.
Agitator trucks shall be equipped with a watertight revolving drum, and shall be capable of transporting and discharging concrete without segregation. The agitation speed of the drum shall be between 2 and 6 revolutions per minute. The volume of mixed concrete permitted in the drum shall not exceed the manufacturer’s rating nor exceed 70% of the gross volume of the drum. Upon approval of the Engineer, truck mixers may be used in lieu of agitator trucks for transportation of central plant mixed concrete. Gross volume of agitator bodies, expressed in cubic metres, shall be as determined by the mixer manufacturer. The interval between introduction of water into mixer drum and final discharge time shall be a maximum of 45 minutes unless the use of additives has been approved. Depending on the type and usage of the approved additives this interval may be extended up to a maximum of 2 hours. During this interval the mixture shall be agitated continuously.
Bodies of non-agitator trucks shall be smooth and watertight. Covers shall be provided when needed for protection against rainfall. The non-agitator trucks shall deliver concrete to the work site in a thoroughly mixed and uniform mass. Uniformity shall be deemed satisfactory if samples from the one-quarter and three-quarter points of the load do not differ more than 2.5 cm in slump. Placing of concrete shall be completed within 30 minutes after introduction of mixing water into the cement and aggregates or if admixture is used at a time to be determined by the Engineer.
(iv) Truck mixing-Concrete may be mixed in truck mixers of approved design. Truck mixing shall be in accordance with the following provisions. The truck mixer shall be a closed, watertight, revolving drum or an open-top revolving-blade or paddle type. It shall combine all ingredients into a thoroughly mixed and uniform mass, and shall discharge the concrete with satisfactory uniformity. A maximum difference of 2.5 cm between slumps of samples from the one-quarter and three-quarter points of the discharge load shall be deemed satisfactory.
Mixing speed for revolving drum type mixers shall not be less than 4 revolutions per minute of the drum nor greater than a speed resulting in a peripheral velocity of the drum of 1 metre per second. For the open-top type mixer, mixing speed shall be between 4 and 16 revolutions per minute of the mixing blades or paddles. Agitation speed for both the revolving-drum and revolving blade type mixers shall be between 2 and 6 revolutions per minute of the drum or mixing blades or paddles.
The capacities of truck mixer shall be in accordance with the manufacturer’s ratings except that they shall not exceed the limitation herein. Standard for normal rated capacity, expressed as percentage of the gross volume of the drum, shall not be more than 50% for truck mixing and 70% for agitating.
The concrete shall be delivered to the site of the work and discharge shall be completed within 45 minutes after the introduction of the mixing water into cement and aggregates unless the use of additives has been approved by the Engineer. Depending on the type and usage of the approved additives this interval may be extended up to a maximum of 2 hours. During this interval the mixture shall be agitated continuously.
When the concrete is mixed in a truck mixer, the mixing operation shall begin within 30 minutes after the cement has been mixed with the aggregates. Except when intended for use exclusively as agitators, truck mixers shall be provided with a water-measuring device, which will measure accurately the quantity of water for each batch. The delivered amount of water shall be within plus or minus 1% of the indicated amount when the tank, if mounted on the truck mixer, is satisfactorily and practically level.
(v) Hand mixing – Hand mixing will not be permitted, except in case of emergency, without written permission from the Engineer. When permitted, it shall be performed only on watertight mixing platforms made of metal, etc. Concrete shall be turned and returned on the platform at least six times and until all particles of the coarse aggregate are covered thoroughly with mortar and the mixture is uniform.
(g) Retempering Concrete
Retempering concrete by adding water will not be permitted under any circumstances. Concrete that is not within the specified slump limits at the time of placement shall not be used. Admixtures for increasing the workability or for accelerating the set will be permitted only with the written approval of the Engineer.
(h) Consistency
Slump will be measured in accordance with AASHTO T 119 or JIS A 1101 and shall be in accordance with Table 10-1-1.
S10.01 (4) Construction
(a) General
The Contractor shall maintain an adequate number of trained and experienced supervisors and foremen at the site to supervise and control the work. All construction, other than the concrete, shall conform to the requirements prescribed in other sections or clauses for the several items of work entering into the complete structure.
(b) Foundation
Preparation of foundations shall conform to the details as shown on the Drawings in accordance with the requirements of Clause S5.01. The elevations of the bottoms of footings as shown on the Drawings are approximate only and the Engineer may order further excavation as necessary to obtain satisfactory foundations.
Pile foundations shall be constructed in accordance with the provisions set out in the other relevant Clauses and as shown on the Drawings.
(c) Falsework
Falsework shall be built on foundations of sufficient strength to carry the loads without appreciable settlement. Falsework that cannot be founded on solid footings must be supported by ample falsework piling provided at the Contractor’s expense.
Before constructing forms or falsework the Contractor, if required, shall submit detailed drawings of proposed forms or falsework for approval by the Engineer, but such approval shall not relieve the Contractor of any of his responsibilities under the Contract for the successful completion of the structure.
(d) Formwork
Before concrete is placed the Engineer shall inspect all formwork and falsework and no concrete shall be placed until the Engineer has inspected and approved such formwork and falsework. Such approval shall not relieve the Contractor of any of his responsibilities under the Contract for the successful completion of the structure.
Internal formwork for hollow slab construction shall be made of plywood, thin metal plate or other materials. These materials shall have sufficient strength to resist the pressure and the buoyancy effects of fresh concrete.
Type and structure of joint and cover for the cylindrical form shall be tight to prevent any leakage of concrete, and shall be approved by the Engineer. Nominal diameter of cylindrical forms shall be the outer diameter, or the outer diameter of projecting portion in case of thin metal plate having projection. The height of the projection shall be less than 10 mm.
Internal forms shall be fixed in the correct position such that they will not displace or deform during placing concrete. U-shape bolts shall be used to fix the internal forms and the method of supporting and fixing the internal forms shall be approved by the Engineer. Care shall be taken to ensure that U-shape bolts and other items can resist the buoyancy forces on the formwork.
In falsework, bridge camber shall be considered in accordance with the Working Drawings prepared by the Contractor and approved by the Engineer.
(e) Reinforcement
The Engineer shall inspect and approve all reinforcement in place in accordance with the requirements of Clause S10.02, before concrete is placed. An experienced steel fixer shall be present while all concrete is placed to ensure that no reinforcement becomes displaced during placing and if it does to reposition reinforcement before placing continues.
(f) Placing Concrete
(i) General – All concrete shall be placed within the time specified in Sub-clause S10.01 (3) (f). Concrete shall be placed in such a manner as to avoid segregation and the displacement of reinforcing bars and shall be spread in horizontal layers where practicable. Concrete shall be placed where necessary inside forms by hand shovels and in no instance shall vibrators be so manipulated to transport concrete inside formwork. Care shall be taken to prevent mortar from spattering forms and reinforcing steel and from drying ahead of the final covering with concrete. When spattering has occurred the forms and steel shall be cleaned with wire brushes or scrapers before concrete is placed around steel or in forms, which have been spattered.
Troughs, pipes, or short chutes used as aids in placing concrete shall be positioned in such a manner that segregation of the concrete will not occur. All chutes, troughs, and pipes shall be kept clean and free from coating of hardened concrete or mortar. Concrete shall not be dropped freely over a vertical distance of more than 1.5 metres.
Concrete shall be placed continuously throughout each section of the structure or between indicated joints if shown on the Drawings or as directed by the Engineer.
If in an emergency it is necessary to stop placing concrete before a section is completed, bulkheads shall be placed as the Engineer may direct and the resulting joint shall be deemed a construction joint, and treated as specified herein below.
(ii) Concrete columns – Concrete in columns or bents shall be placed in one continuous operation unless shown on the Drawings or permitted by the Engineer.
(iii) Concrete slab and girder spans – Slabs and girders having spans of 10 metres or less shall be placed in one continuous operation unless otherwise stated on the Drawings. Concrete preferably shall be deposited by beginning at the centre of the span working from the centre toward the ends.
Concrete in slab spans shall be placed in one continuous operation and in one layer for each span, unless otherwise stated on the Drawings.
Concrete in girders spanning more than 10 metres may be placed in two operations, the first operation being the placing of concrete in the girder stems to the bottom of the slab haunches or the bottom of the slab whichever is applicable. A period of at least 24 hours shall elapse between the completion of placing concrete in the girder and the commencement of placing concrete in slab.
The construction procedure for the concrete deck slab on steel box girders shall be so arranged as to eliminate excessive stress in new or recently placed concrete.
Immediately before placing concrete, the top surface of the previously placed concrete shall be hammered with a sharp hand tool (scabbled) until the aggregate is exposed and cleaned. The Contractor shall check all falsework for shrinkage and settlement, and shall tighten all wedges to ensure minimum deflection of all formwork.
(iv) Walls, piers, etc. – Where walls, piers, columns, struts, posts and other such structural members allow horizontal construction joints, concrete shall not be placed on top of other concrete which has not been allowed to set for 12 hours or more.
Work shall not be discontinued within 45 centimetres of the top of any face, unless provision has been made for a coping less than 45 centimetres thick, in which case, if permitted by the Engineer, the construction joint may be made at the underside of the coping.
(v) Culverts – The slabs of box culverts shall be placed for their full depth in one mass or layer and allowed to set not less than 12 hours before any additional work is done on them.
Before concrete is placed in sidewalls, bottom slabs shall be cleaned of all shavings, sticks, sawdust and other extraneous material.
The Contractor shall submit to the Engineer for approval his proposals for pouring culvert walls before commencing culvert construction. Concrete shall not be placed in layers more than one metre high relative to the concrete already placed. Deposition shall proceed in a systematic manner.
(vi) Depositing concrete underwater – Concrete shall not be deposited in water except with the approval of the Engineer and with his immediate supervision, and by the method described in this paragraph.
To prevent segregation, the concrete shall be carefully placed in a compact mass in its final position by means of a tremie tube or pipe, or a closed bottom-dump bucket, or by other means, and shall not be disturbed after being deposited. Special care must be exercised to maintain still water at the point of deposit. Concrete shall not be placed in running water. The method of depositing concrete shall be so regulated as to produce approximately horizontal surfaces. Concrete seals shall be placed in one continuous operation. When a tremie tube or pipe is used, it shall consist of a tube or pipe not less than 25 centimetres in diameter, constructed in sections having flanged couplings fitted with gaskets.
The means of supporting the tremie shall be such as to permit free movement of the discharge end over the entire top of the concrete and permit its being lowered rapidly when necessary to choke off or retard the flow. The tremie shall be filled by a method that will prevent washing of the concrete. The discharge end shall be completely submerged in concrete at all times and the tremie shall contain sufficient concrete to prevent any water entry.
When concrete is placed with a bottom-dump bucket, the bucket shall have a capacity of not less than 1.20 cubic metres and shall be equipped with loose-fitting top covers. The bottom door shall open freely downward and outward when tripped. The bucket shall be completely filled and be lowered gradually and carefully until it rests on the surface upon which the concrete is to be deposited. It shall then be raised very slowly during the discharge travel, the intent being to maintain, as nearly as possible, still water at the point of discharge and to avoid agitating the mixture.
Dewatering shall proceed only when the concrete seal is considered strong enough to withstand any pressures to be exerted upon it. This time will be decided by the Engineer. All laitance or other unsatisfactory material shall be removed from the exposed surface by scraping, jetting, chipping or other means which will not unduly injure the seal.
(vii) Construction joints – Construction joints shall be located where shown on the Drawings or permitted or instructed by the Engineer. Construction joints shall be perpendicular to the principal lines of stress and in general shall be located at points of minimum shear.
At horizontal construction joints, details shall be as approved by the Engineer. Before placing fresh concrete, the surfaces of construction joints shall be scabbled, sandblasted or washed and scrubbed with a wire brush to expose clean aggregate, drenched with water until saturated, and kept saturated until the new concrete is placed. Immediately prior to placing new concrete the forms shall be drawn tight against the concrete already in place and the old surface shall be coated thoroughly with a 1.5 mm thick coating of neat cement mortar. Concrete in substructures shall be placed in such a manner that all exposed horizontal construction joints will be truly horizontal.
Where vertical construction joints are necessary, reinforcing bars shall extend across the joint in such a manner as to make the structure monolithic. Special care shall be taken to avoid construction joints through panelled wing walls or other large surfaces, which are to have an architectural finish. Necessary dowel, load-transfer devices, and bonding devices shall be placed as shown on the Drawings or directed by the Engineer.
(viii) Cut-off plate for water stops used for the expansion joints shall be flexible PVC to JIS K 6773 and shall be placed in accordance with the Drawings. The water stops shall be held firmly in place to prevent displacement during concreting. If after placing concrete water stops are materially out of position or shape, the surrounding concrete shall be removed, the water stop reset, and the concrete replaced, all at the Contractor’s expense.
Water stop shall be furnished full length for each straight portion of the joint, without field splices. Water stop shall be cut and spliced at changes in direction, as may be necessary to avoid buckling or distortion. All field splices shall be performed by heat sealing, hot air welding or vulcanising the adjacent surfaces in accordance with the manufacturer’s recommendations to form continuous watertight joints.
(ix) Open joints – Open joints shall be constructed where shown on the Drawings by insertion and subsequent removal of a wooden strip, metal plate, or other approved material. The insertion and removal of the template shall be accomplished without chipping or breaking the corners of the concrete. Reinforcement shall not extend across an open joint unless so specified on the Drawings.
(x) Anchor bolts – All necessary anchor bolts in piers or abutments shall be accurately set in holes formed while the concrete is being placed. Holes may be formed by inserting in the fresh concrete oiled wooden plugs, metal pipe sleeves, or other approved devices, and withdrawing them after the concrete has partially set. Holes so formed shall be at least 10 cm in diameter. Bolts shall be set accurately and fixed with grout completely filling the holes. The grout shall be non-shrink mortar of a type approved by the Engineer.
Anchor bolts used in connection with expansion shoes, rollers, and rockers shall be located with due regard to the temperature at the time of erection. Care shall be taken that full and free movement of the superstructure at the moveable bearings is not restricted by improper setting or adjustment of bearings or anchor bolt and nuts. All anchor bolts shall be galvanized after erection.
(xi) Shoes and bearing plates – Bridge seat bearing areas shall preferably be finished high and ground to the level required. Shoes and bearing plates shall be set as provided in Clause S10.11.
(xii) Drainage holes and weep holes – Drainage holes and weep holes shall be constructed in the manner and at the locations indicated on the Drawings or required by the Engineer. Ports or vents for equalizing hydrostatic pressure shall be placed below low water.
Forms for weep holes through concrete shall be PVC pipe. Exposed surfaces of weep drainpipe shall be flush with the concrete.
(xiii) Pipe, conduits, and ducts – Pipes, conduits, and ducts that are to be encased in concrete shall be installed by the Contractor before the concrete is placed. Unless otherwise indicated, pipe embedded in concrete shall be standard, lightweight, non-corrosive pipes. Pipes shall be held or braced rigidly during concrete placement in order to prevent their displacement.
(xiv) Piers and abutments – No superstructure load shall be placed upon finished bents, piers, or abutments until the Engineer so directs, but the minimum time allowed for the hardening of concrete in the substructure before any load of the superstructure is placed thereon shall be 7 days when normal Portland cement is used.
(g) Curing Concrete
Immediately after forms have been removed and finishing completed, all concrete shall be cured by one of the following methods. The Engineer will specify the concrete surface, which may be cured by either method.
(i) Water method – The entire exposed surfaces other than slabs shall be protected from the sun and the whole structure shall be covered with wet burlap, cotton mats, or other suitable fabric for a period of at least seven days. These materials shall be kept thoroughly wet for the entire curing period. Curbs, walls, and other surfaces requiring a rubbed finish may have the covering temporarily removed for finishing, but the covering must be restored as soon as possible. All concrete slabs shall be covered as soon as possible with sand, earth or other suitable material and kept thoroughly wet for at least seven days. This covering material shall not be cleared from the surface of the concrete slabs for a period of twenty-one days.
If wood forms are allowed to remain in place during the curing period, they shall be kept moist at all times to prevent them from shrinking.
(ii) Membrane forming curing compound – All surfaces shall be given the required surface finish prior to application of the curing compound. During the finishing period, the concrete shall be protected by the water method of curing.
Membrane curing compound shall be applied after the removal of forms, or after the disappearance of surface water. It can be sprayed or applied to the concrete surface by means of an applicator in one or more coats at the rate instructed by the manufacturer.
Should the membrane seal be broken or damaged before the expiration of the curing period, the damaged area shall be immediately repaired by the application of additional membrane material.
The Contractor’s proposals for the use of liquid membrane curing compound and the locations shall be subject to the approval of the Engineer.
(h) Removal of Formwork and Falsework
(i) Time of removal – formwork and falsework shall not be removed without the approval of the Engineer. The Engineer’s approval shall not relieve the Contractor of responsibility for the safety of the work. Blocks and bracing shall be removed at the same time as the forms and in no case shall any portion of wooden forms be left in the concrete.
Falsework removal for continuous or cantilevered structures shall be as approved and directed by the Engineer and shall be such that the structure is gradually subjected to its working stress.
When the time for removal of forms and supports is determined based on concrete strength tests, such removal shall not begin until the concrete has attained the percentage of the specified design strength shown in the table below.
If field operations are not controlled by compressive strength tests, the time shown below (in the table) for removal of forms and supports shall be used as a minimum.
In continuous structures, falsework shall not be released in any span until the first and second adjoining spans on each side have reached the strength specified herein or in the special provisions. When cast-in-place post-tensioned bridges are constructed, falsework shall remain in place until all post-tensioning has been accomplished.
Removal of Formwork and Falsework
|
Structure |
Standard Concrete |
Early Strength Concrete |
Percentage of Design Strength |
| Centring under girders, beams, frames or archesFloor slabsWallsColumnsSide of beams and all other vertical surfaces |
14 days 14 days 1 day 2 days
1 day |
7 days 7 days 12 hours 1 day
12 hours |
80% 70% - -
- |
Falsework under all spans of continuous structures shall be completely released before concrete is placed in railings and bridge parapets.
Forms and falsework shall not be released from under concrete without first determining if the concrete has gained adequate strength without regard to the time element. In the absence of strength determinations, the forms and falsework are to remain in place until removal is permitted by the Engineer.
The forms for footings constructed within cofferdams or cribs may be left in place when, in the opinion of the Engineer, their removal would endanger the safety of the cofferdam or crib, and
when the forms so left intact will not be exposed to view in the finished structure. All other forms shall be removed whether above or below the ground line or water level.
All formwork shall be removed from the cells of concrete box girders within which utilities are required, and all formwork except that necessary to support the deck slab shall be removed from the remaining cells of the box girder.
To facilitate finishing, forms used on ornamental work, railings, parapets, and exposed vertical surfaces shall be removed at least 12 but not more than 48 hours later depending upon weather conditions.
In order to determine the condition of concrete in columns, forms to columns shall always be removed before releasing supports from beneath beams and girders.
Falsework supporting the deck of rigid frame structures shall not be removed until fill has been placed behind the vertical legs.
(ii) Patching – Immediately following removal of the forms all projecting wires or metal devices that have been used for holding the forms in place shall be removed or cut back at least 2.5 cm beneath the surface of the concrete. Fins or runs of mortar and all irregularities caused by form joints shall be removed. Small holes, depressions, and voids that show on the concrete shall be filled with cement mortar mixed in the same proportions as that used in the body of the work, except without coarse aggregate.
The surface of this mortar shall be floated with a wooden float before initial set takes place. It shall be uniform in colour with the surrounding concrete and neat and workmanlike in appearance.
(iii) Cause for rejection – Excessive honeycombing shall be sufficient cause for rejection of portions of the structure containing this honeycombing. The Contractor, on receipt of written orders from the Engineer, shall remove and rebuild such portions of the structure at his own expense.
(i) Finishing Concrete
All concrete surfaces exposed in the completed work shall comply with the requirements of Item (iii) Ordinary finish herein except where otherwise shown or specified.
(i) Concrete decks – Immediately after placing concrete, concrete decks shall be struck off with templates to provide proper transverse sections and shall be hand finished smooth to the concrete levels. Finish shall be slightly but uniformly roughened by brooming. The finished surface shall not vary more than 10 millimetres from a 4-metre straightedge placed parallel to the centreline of the roadway and 10 millimetres from a transverse template cut to the true cross section of the roadway.
(ii) Curb and footpath surface – Exposed faces of curbs and footpath shall be finished true to lines and grades. The curb surface shall be wood floated to a smooth but non-slippery finish. Footpath surfaces shall be slightly but uniformly roughened by brooming across the direction of travel.
(iii) Ordinary finish – An ordinary finish is defined as the finish left on a surface after the removal of the forms when all holes left by form ties have been filled, and any minor surface defects have been repaired. The surface shall be true and even, free from depressions or projections and of reasonably uniform colour.
Repaired surfaces, the appearance of which is not satisfactory, shall be “rubbed” as specified in Item (iv) Rubbed finish.
The concrete in bridge seats, caps, and tops of walls shall be struck off with a straightedge and floated to true grade. Unless shown on the Drawings the use of mortar topping for concrete surfaces will not be permitted.
(iv) Rubbed finish – After the removal of forms the rubbing of concrete shall be started as soon as its condition will permit. Immediately before starting this work the concrete shall be kept thoroughly saturated with water. Sufficient time shall have elapsed before the wetting down to allow the mortar used in patching to set thoroughly. Surfaces to be finished shall be rubbed with a medium coarse carborundum stone, using a small amount of mortar on its face. The mortar shall be composed of cement and fine sand mixed in the same proportions as those used in the concrete being finished. Rubbing shall be continued until all form marks, projections and irregularities have been removed, all voids filled, and a uniform surface has been obtained. The paste produced by this rubbing shall be left in place. After all concrete above the surface being treated has been cast, the final finish shall be obtained by rubbing with a fine carborundum stone and water. This rubbing shall be continued until the entire surface is of a smooth texture and uniform colour.
After the final rubbing has been completed and the surface has dried, it shall be rubbed with burlap to remove loose particles and laitance. The final surface shall be free from all unsound patches, paste, powder and objectionable marks.
(v) Backfill and road fills – All spaces which have been excavated and the volumes of which are not occupied by the concrete structure shall be backfilled and compacted with acceptable material in accordance with the provisions of Section 5 of these Specifications.
If there is likelihood of water accumulating behind any wall, the backfill shall not be placed until after the retaining, diaphragm, or spandrel walls are 28 days old. No fill shall be placed over arches and slabs until the concrete is 28 days old or until test specimens indicate the concrete has attained the required 28-day strength.
(vi) Loading – Traffic or heavy construction equipment shall not be allowed on reinforced concrete structures until 28 days have elapsed from the last placing of concrete except as noted below. If it is proposed to use the structure at an earlier date, extra test specimens shall be cast. The structure may be used when tests of these specimens show that the concrete has attained its specified 28-day strength.
(j) Cleaning Up
Upon completion of structure and before final acceptance, the Contractor shall remove all falsework, falsework piling, etc., down to 1.0 metre below the finished ground line. Excavated or useless materials, rubbish, etc. shall be removed from the site and the site shall be left in a neat and presentable condition satisfactory to the Engineer.
S10.01 (5) Method of Measurement
Concrete shall be measured by the number of cubic metres of the several classes complete in place and accepted. In computing quantities the dimensions used shall be those shown on the Drawings or ordered in writing by the Engineer but the measurement shall not include any concrete used for the construction of temporary works. No deduction from the measured quantity shall be made for the volume occupied by pipes less than 20 cm in diameter nor for reinforcing steel, anchors, conduits, weep holes or piling except that deductions will be made for the volume of structural steel, including steel piling, encased in concrete. The measurement shall not include any concrete used in the construction of cofferdams or falsework, or the volume of forms or falsework.
At locations where steel access doors are required for maintenance of box girders, these will not be paid for separately but will be a subsidiary obligation of the Contractor under the pay item for the relevant class of concrete. The full volume of concrete will be measured for payment and no deduction will be made for the volume of concrete omitted to provide the access.
No pay allowance shall be made for any increased cement content, neither for any admixtures nor for any finishing of any description of concrete or concrete floor. Any Class B concrete permitted to be constructed where Class C, D or E concrete was specified shall be measured for payment as Class C, D and E concrete, respectively. Any Class C concrete permitted to be constructed where Class D or E concrete was specified shall be measured for payment as Class D or E concrete.
Unless described otherwise, concrete used for the works on other Pay Items in these Specifications will not be measured separately for payment under this Clause S10.01.
The quantities of reinforcing steel and other Contract items which are included in the completed and accepted structure shall be measured for payment as described for the separate items involved.
S10.01 (6) Basis of Payment
The work measured as provided above for the class or classes of concrete specified, shall be paid for at the Contract unit price per cubic metre for concrete as detailed below. The payment shall be full compensation for furnishing and placing all materials, including all labour, tools, equipment, formwork, falsework (scaffolding and supporting), including piling of formwork for beams and slabs; for mixing, placing, finishing and curing the concrete, etc., and all incidental work thereto including the provision and construction of drainage falls and systems and weepholes. The supply, fixing and finishing of expansion joints and reinforcing steel shall be paid for separately.
|
Pay Item No. |
Name |
Unit of Measurement |
||
|
10.01 |
(A-1) | Structural Concrete, | Class A-1 |
cubic metre |
|
10.01 |
(A-2) | Structural Concrete, | Class A-2 |
cubic metre |
|
10.01 |
(C-1) | Structural Concrete, | Class C-1 |
cubic metre |
|
10.01 |
(C-4) | Structural Concrete, | Class C-4 |
cubic metre |
|
10.01 |
(C-5) | Structural Concrete, | Class C-5 |
cubic metre |
|
10.01 |
(E-1) | Structural Concrete, | Class E-1 |
cubic metre |
|
10.01 |
(G) | Structural Concrete, | Class G |
cubic metre |
S10.02 Reinforcing Steel Bars
S10.02 (1) Description
This work shall consist of furnishing, fabricating, and placing reinforcing steel bars of the type and size provided in accordance with these Specifications and in reasonably close conformity with the Drawings or as directed by the Engineer.
S10.02 (2) Materials
Reinforcing steel shall conform to the requirements of the following specifications except that the weights of the standard bar sizes will be taken as per Tables 10-2-1 and 10-2-2, irrespective of the specification used in manufacture.
Round Bar: A-I (CT-3) 22TCN 18-79; or JIS G 3112 (Grade SR 235); or ASTM A615
Deformed Bars:A-II (CT-5) 22TCN 18-79; or JIS G 3112 (Grade SD 295A); or JIS G 3112 (Grade SD 345); or
ASTM A615
Reinforcing bars shall be kept off the ground and stored within a building or provided with suitable cover.
S10.02 (3) Construction
(a) Fabrication
(i) Reinforcing bars shall be accurately formed to the shapes and dimensions indicated in the design, and shall be fabricated in a manner that will not injure the material.
(ii) Unless otherwise permitted, all reinforcing bars requiring bending shall be bent cold. When reinforcing bars are bent by heating, the entire operation shall be approved by the Engineer. Should the Engineer approve the application of heat for field bending reinforcing bars, precautions shall be taken to ensure that the physical properties of the steel will not be materially altered.
(iii) Reinforcing bars that cannot be straightened by means of fabrication shall not be used. Bars partially embedded in concrete shall not be bent except as shown on the Drawings or otherwise permitted.
(iv) Qualified men shall be employed for cutting and bending, and proper appliances shall be provided for such work.
(v) If it is necessary for the Engineer to ascertain the quality of reinforcing bars, the Contractor shall test reinforcing bars, at his own expense, by means as directed by the Engineer.
(b) Placing
(i) Reinforcing bars before being positioned shall be cleaned and free from rust, dirt, mud and loose scale and from paint, oil, or any other foreign substance that destroys or reduces the bond.
(ii) Reinforcing bars shall be accurately placed in proper position so that they will be firmly held during placing concrete. Reinforcing bars for erecting shall be used when needed.
(iii) Bars shall be tied at all intersections by using annealed iron wire 0.9 mm or larger diameter or suitable clips. Welding will not be permitted for this requirement.
(iv) Distances from the forms shall be maintained correctly by means of metal hangers, mortar blocks, metal supports, or other supports approved by the Engineer.
(v) Reinforcing bars shall be inspected by the Engineer after placing. When a long time has elapsed after placing reinforcing bars, they shall be cleaned and inspected again by the Engineer before placing concrete.
(c) Splicing
(i) When it is necessary to splice reinforcing bar at points other than shown on the designs, positions and methods of splicing shall be determined based on strength calculations approved by the Engineer.
(ii) In lapped splices, the bars shall be lapped the required length and wired together at several points by using annealed iron wire larger than 0.9 mm.
(iii) Exposed reinforcing bars intended for bonding with future extensions shall be effectively protected from injury and corrosion.
(iv) Welding of reinforcing steel shall be done only if detailed on the Drawings or if authorized by the Engineer in writing.
(v) Substitution of different size bars shall be permitted only upon the specific authorization of the Engineer.
S10.02 (4) Method of Measurement
The quantity of reinforcing steel bar to be paid for shall be the weight (kilogram) of reinforcing bar erected as shown on the working drawings or ordered by the Engineer in writing. The weight calculated will be based upon the following tables:
Table 10-2-1 Unit Weights of Plain Round Bars
|
Nom. Bar Size (dia. mm) |
D9 | D13 | D16 | D19 | D22 | D25 | D28 |
|
Weight per linear metre in kg |
0.499 |
1.040 |
1.580 |
2.230 |
2.980 |
3.850 |
4.830 |
Table 10-2-1 Unit Weights of Plain Round Bars – cont.
|
Nom. Bar Size (dia. mm) |
D32 | D36 | D38 | D42 | D46 | D48 | D50 |
|
Weight per linear metre in kg |
6.310 |
7.990 |
8.900 |
10.900 |
13.000 |
14.200 |
15.400 |
|
Nom. Bar Size (dia. mm) |
D55 | D60 | D65 | D70 | D75 | D80 | D85 |
|
Weight per linear metre in kg |
18.700 |
22.200 |
26.000 |
30.200 |
34.700 |
39.500 |
44.500 |
Table 10-2-2 Unit Weights of Deformed Bars
|
Nom Bar Size (dia. mm) |
D13 |
D16 |
D19 |
D22 |
D25 |
D29 |
D32 |
|
Weight per linear metre in kg |
0.995 |
1.560 |
2.250 |
3.040 |
3.980 |
5.040 |
6.230 |
The lengths to be taken in calculating the weight for the purpose of payment shall be shown on the Drawings or ordered in writing by the Engineer.
No measurement or payment will be made for splices added by the Contractor for his convenience or for splices, which are not shown on the Drawings and are not approved by the Engineer.
Clips, ties or other material used for positioning and fastening the reinforcing bars in place shall not be measured for payment. Reinforcing steel bars used for the pay items in Sections 6, 12 and 13 (except foundation for high mast lighting pole) and for the Pay Items 10.03, 10.04, 10.05, 10.07, 10.10, 10.11 and 10.12 of these Specifications, shall not be measured for payment in this Clause S10.02.
S10.02 (5) Basis of Payment
The accepted quantities of reinforcing steel bar determined as provided above shall be paid for at the Contract price per kilogram, completed in place.
This payment shall be full compensation for furnishing all labour, equipment, and materials, necessary for fabricating, bending, assembling and erecting reinforcing bar, for unloading at the specific location, storing and handling of reinforcing steel bar.
Payment Item No. Name Unit of Measurement
10.02 Reinforcing Steel Bars kilogram
S10.03 Prestressed Concrete
S10.03 (1) Description
(a) General
This work shall consist of prestressed concrete structures and the prestressed concrete portions of composite structures, constructed in close conformity with the lines, grades, design, and dimensions shown on the Drawings, or established by the Engineer and in accordance with this and other specification items involved.
The work shall include the furnishing and installing of any appurtenant items necessary for the particular prestressing system to be used, including but not limited to ducts, anchorage assemblies and grout.
It shall include the manufacture, transportation, and storage of beams, slabs, and other structural members of pre-cast concrete prestressed by either pre-tensioning or post-tensioning methods. It shall also include the installation of all pre-cast prestressed members.
For cast-in-place prestressed concrete, the term “member” as used in this section shall be considered to mean the concrete, which is to be prestressed.
(b) Definitions
Post-tensioning is defined as any method of prestressing concrete in which the tensioned reinforcement is tensioned after the concrete has hardened to the required strength. Pre-tensioning is defined as any method of prestressing concrete in which the tensioned reinforcement is tensioned before the concrete is placed. Prestressing reinforcement is defined as any reinforcement to which pre-stress is applied by post-tensioning or pre-tensioning.
S10.03 (2) Materials
(a) General
All materials to be furnished and used, which are not covered in this Clause, shall conform to the requirements stipulated in other applicable Clauses.
(b) Reinforcement – General
(i) Non-prestressing reinforcement shall conform either to Clause S10.02 or, where prestressing quality is called for on the Drawings it shall conform to the requirements for prestressing steel.
(ii) Prestressing steel shall be high tensile strength steel wire, high tensile strength steel strand or high tensile strength steel bar.
(c) Prestressing Steel
(i) High tensile strength steel wire shall be stress relieved and shall conform to the requirements of ASTM A421-91 or JIS G 3536 “Un-coated Stress Relieved Wire for Prestressed Concrete”.
ii) High tensile steel strand shall be weld free and stress relieved after stranding and shall conform to the requirements of ASTM A 416-90a or JIS G 3536 “Un-coated Seven Wire Stress Relieved Strand for Prestressed Concrete”.
(iii) High tensile steel bar shall be stress relieved and shall conform to the requirements of ASTM A 722 or JIS G 3109.
(iv) Testing – The testing of prestressing reinforcement shall be in accordance with the requirements of the ASTM Specifications for the type of system intended to be used or as instructed by the Engineer.
(d) Anchorages
All post-tensioned prestressing steel shall be secured at the ends by means of approved permanent type anchoring devices, which shall be of steel bearing plate type.
All anchorage devices for post-tensioning shall be capable of holding the prestressing steel at a load producing a stress of not less than 95 percent of the guaranteed minimum tensile strength of the prestressing steel.
Fixed anchorages for tendons shall be of steel bearing plate type.
It shall be the responsibility of the Contractor to determine the required bursting reinforcements in the local zone for the particular shape and design of the anchorage devices proposed. Details of such reinforcements shall be incorporated into the working drawings to be supplied under Clause S10.03(3)(b) Plan of Operation.
(e) Ducts
All ducts shall be metallic and shall be mortar-tight. Ducts shall be strong enough to maintain their shape under working stresses, and where grouting is specified, air and grout holes shall be provided with pipes or other devices so that the injection of grout will completely fill all void spaces within the entire length of the duct.
(f) Grout
Grout shall consist of Portland cement, water, and an expansive admixture plus retarder as approved by the Engineer. Water shall be potable. No admixtures containing chlorides or nitrates shall be used.
The Contractor shall submit the proportion of mixing for approval of the Engineer but in no case shall the W/C ratio proposed be less than 0.40
Water shall be first added to the mixer followed by cement and admixture. The grout shall be mixed in mechanical mixing equipment of a type that will produce uniform and thoroughly mixed grout. Re-tempering of grout will not be permitted. Grout shall be continuously agitated until it is pumped.
(g) Concrete
Concrete shall conform to the requirements of Class A-1,A-2 or A-3 concrete of Clause S10.01 of this Specification and to the requirements specified below unless otherwise stated in the Drawings.
The Contractor shall develop his own mix designs, which shall be submitted to the Engineer for approval.
The maximum size of aggregate for use in the manufacture of prestressed concrete shall be 2 centimetres.
S10.03 (3) Construction
(a) General
The Contractor shall provide a Technician skilled in the use of the system of prestressing to be used, who shall supervise the work and give the Engineer such assistance as the Engineer may consider necessary.
The Contractor shall provide all equipment necessary for the construction and the prestressing. Prestressing shall be done with approved proprietary system jacking equipment. If hydraulic jacks are used they shall be equipped with accurately reading pressure gauges. The combination of jack and gauge shall be calibrated and a graph or table showing the calibration shall be furnished to the Engineer. Should other types of jacks be used, calibrated proving rings or other devices shall be furnished so that the jacking forces may be accurately known.
All of the applicable requirements of Clause S10.01 (4) “Construction” shall be complied with, except as may be modified in this Clause. Prestressed concrete shall be formed, stressed, placed, cured, and protected at shops, manufacturing plants, and locations approved by the Engineer, where the fabrication of such members may be properly inspected and controlled.
(b) Plan of Operation
The Contractor shall, prepare, check and submit to the Engineer for approval complete detailed working (shop) drawings or schedules together with calculations as required by the Engineer showing, but not limited to, the following:
(i) Contractor’s alternative designs if the submission of alternatives is approved;
(ii) Contractor’s details of proposed manufacture and construction;
(iii) sequence of operations proposed complete with structural analysis at each stage of construction if so required by the Engineer;
(iv) dimensions and complete descriptions of all devices, joints, bearings, and anchorages not specified or detailed in the Contract Documents,
(v) deflection control measures,
(vi) details of travelling forms, suspended scaffolding of mid-spans if used,
(vii) temporary fixing/stabilising method of the supports at the pier tables while in cantilevering operations,
(viii) method and timing of the insertion of the prestressing cables
Concrete shall not be cast prior to the Engineer’s approval of the Contractor’s Drawings, of concrete mixtures, of formwork and falsework, of methods of application of prestressing forces, of methods of placing, of curing, of protecting, of handling and of erecting members. Any alternative to the design in the Contract Documents , shall be subject to the Engineer’s approval before manufacture or construction.
The Contractor shall inform the Engineer not less than 7 days in advance of the probable date of commencement of manufacture and the dates when casting of units, tensioning of steel and transfer of stress will be undertaken for the first time.
(c) Placing Steel
All steel units shall be accurately placed in the position shown on the Drawings and rigidly held during placing and setting of the concrete. Distance from the forms shall be maintained by stays, formwork spacers, ties, hangers, or other approved support. Formwork spacers for holding units from contact with the forms shall be of approved material, shape and dimensions. Layers of units shall be separated by suitable wire spacers. Wooden blocks shall not be used.
(d) Curing
Steam curing process may be used as an alternative to water curing. The casting bed for any unit cured with steam shall be completely enclosed to prevent steam escaping and exclude outside atmosphere. Two to four hours after placing concrete and after the concrete has undergone initial set, the first application of steam shall be made. If retarding admixtures have been used, the delay before application of the steam shall be increased to four to six hours. Water curing methods shall be used from the time the concrete is placed until steam is first applied.
The steam shall be at 100% relative humidity to prevent loss of moisture and to provide moisture for proper hydration of the cement. Application of the steam shall not be directly on the concrete. During the application of the steam, the ambient air temperature shall increase at a rate not to exceed 22o C (Celsius) per hour until the maximum temperature is reached and shall be held until the concrete has reached the desired strength. In discontinuing the steam application, the ambient air temperature shall not decrease at a rate to exceed 22o C per hour until a temperature has been reached 10o C above the temperature of the air to which the concrete will be exposed. The maximum curing temperature shall be from 60 o C to 67 o C.
If the Contractor elects to cure by any other special method, the method and details shall be subject to the approval of the Engineer.
Except as specified or otherwise approved, curing shall comply with the requirements in Clause S10.01.
(e) Post-tensioning Method
Tensioning of the prestressing reinforcement shall not be commenced until tests on concrete cylinders, manufactured of the same concrete of the particular member to be prestressed has attained compressive strength indicated in the Drawings or directed by the Engineer.
After all concrete has attained the required strength, the prestressing reinforcement shall be stressed by means of jacks to the desired tension and the stress transferred to the end anchorage.
Cast-in-place concrete, for other than segmentally constructed bridge, shall not be post-tensioned until at least 10 days after the last concrete has been placed in the member to be post-tensioned or until the compressive strength of said placed concrete has reached the strength specified for the concrete at the time of stressing.
All side and inside forms for girders shall be removed before post-tensioning. The falsework under the bottom slab supporting the superstructure shall not be released until a minimum of 48 hours have elapsed after grouting of the post-tension tendons nor until all other conditions of the specifications have been met. The supporting falsework shall be constructed in such a manner that the superstructure will be free to lift off the falsework and shorten during post-tensioning.
The tensioning process shall be so conducted that the tension being applied and the elongation of the prestressing elements may be measured at all times and the method of stressing control such as mentioned herein shall be approved by the Engineer prior to the commencement.
A record shall be kept of gauge pressures and elongation at all times and submitted to the Engineer for his approval.
The load from the anchoring device shall be distributed to the concrete by means of approved devices that will effectively distribute the load to the concrete.
Where the end of a post-tensioned assembly will not be covered by concrete, the anchoring devices shall be recessed so that the ends of the prestressing steel and all parts of the anchoring devices will be at least 50 mm inside of the end surface of the members, unless a greater embedment is shown on the plans. Following post-tensioning, the recesses shall be filled with the approved non-shrinkage mortar, and finished as shown in the Drawings.
(f) Bonding Steel
Post-tensioned steel shall be bonded to the concrete. All prestressing steel to be bonded to the concrete shall be free of dirt, loose rust, grease or other deleterious substances.
Prestressing steel shall be bonded to the concrete by filling the void space between the duct and the tendon with a non-shrink (expanding) grout. All ducts shall be clean and free of deleterious materials that would impair bonding of the grout or interfere with grouting procedures.
All grout shall pass through a screen with 1.20 mm maximum clear openings prior to being introduced into the grout pump.
Grout injection pipes shall be fitted with positive mechanical shutoff valves. Vents and ejection pipes shall be fitted with valves, caps, or other devices capable of withstanding the pumping pressure. Valves and caps shall not be removed or opened until the grout has set.
(g) Handling, Transport and Storage
Pre-cast prestressed concrete shall not be moved from the casting position or transported until the concrete has attained a compressive strength of 90% of the specified 28-day strength. Extreme care shall be exercised in handling and moving pre-cast prestressed concrete members. Pre-cast girders and slabs shall be transported in an upright position, shock shall be avoided and the points of support and directions of the reactions with respect to the member shall be approximately the same during transporting and storage as when the member is in its final position. If the Contractor deems it expedient to transport or store pre-cast prestressed units in other than this position, it shall be done at his own risk after notifying the Engineer of his intention to do so. Any unit considered by the Engineer to have become substandard shall be rejected and replaced at the Contractor’s expense by an acceptable unit.
(h) Marking of Pre-cast Prestressed Members
Each pre-cast prestressed member is to be uniquely and permanently marked so as to show its type, date of casting and reinforcement.
(i) Testing of Pre-cast Prestressed Members
When directed by the Engineer one or more beams shall be subjected to a loading test. The Contractor shall obtain the prior approval of the Engineer to the detailed arrangements for the testing. A beam which is to undergo testing shall be supported at its design points of bearing and the upward deflection due to the prestressing force measured relative to a line joining these points. Equal loads shall then be applied at the third points in ten equal increments, the total being sustained for 5 minutes. The beam shall then be unloaded.
The mid-span deflection relative to the reference line shall be measured for each increment of load. The load deflection curve plotted from these values must show no appreciable variation from a straight line. The Drawings shall show, or the Engineer shall direct, the loads to be applied and the corresponding deflections, which must not be exceeded.
Any beam, which fails to satisfy the Engineer under the prescribed test, shall be rejected, and additional beams then tested at the Contractor’s expense.
The Contractor shall supply to the Engineer record sheets of the tests showing date of test, the loads, deflections, and load deflection curves, calculated values of “E” and the strength of the concrete at release as indicated by the relevant cylinder test results.
The tests are to be carried out on units selected by and in the presence of the Engineer after he has agreed to the method of testing and form of records. The cost of such tests and records shall be included in the Contract unit prices.
S10.03 (4) Method of Measurement
The quantity of prestressed concrete I-girders to be measured for payment shall be the actual number of pre-cast prestressed concrete structural members, installed in place, completed and accepted. Each member shall include the concrete, reinforcement and prestressing steel, and other such material contained within or attached to the beam or slab unit.
Prestressed cast-in-place concrete members will be paid for on the basis of the number of cubic metres of concrete, the weight (kg) of reinforcing steel and the weight (kg) of prestressing steel respectively. The weight of prestressing steel will be based on the net length installed between bearing plates of anchoring devices and the unit weights of material as given in the appropriate specifications. For concrete, reference is made to Clause S10.01 and for reinforcing steel reference is made to Clause S10.02.
S10.03 (5) Basis of Payment
The work, measured as provided above, shall be paid for at the Contract unit price for any item listed below which appears in the Bid Schedule. The prices and payment shall be full compensation for furnishing and placing all materials including all labour, tools, equipment and incidentals necessary to complete the work prescribed in this Clause. The payment of prestressing cable shall include the work of tensioning, grouting, anchorages and ducts. The unit price for I-girders will be deemed to include all concrete, reinforcement, prestressing cables, hauling and erection.
|
Pay Item No. |
Name |
Unit of Measurement |
||||
|
10.03 |
(1) | PC Tendon, Strand, | Type A (12T15.2) |
kilogram |
||
|
10.03 |
(2) | PC Tendon, Strand, | Type B (4T15.2) |
kilogram |
||
|
10.03 |
(3) | PC Tendon, Strand, | Type C (3T15.2) |
kilogram |
||
|
10.03 |
(4) | PC Tendon, Strand, | Type D (12T12.7) |
kilogram |
||
|
10.03 |
(5) | PC Tendon, Strand, | Type E (7T12.7) |
kilogram |
||
|
10.03 |
(6) | PC Tendon, Bar, | Type F (F 32) |
kilogram |
||
|
10.03 |
(7) | PC I-Girder, Length |
20m; |
Height | 1.65m |
each |
|
10.03 |
(8) | PC I-Girder, Length |
28m; |
Height | 1.50m |
each |
|
10.03 |
(9) | PC I-Girder, Length |
28m; |
Height | 1.65m |
each |
|
10.03 |
(10) | PC I-Girder, Length |
33m; |
Height | 1.65m |
each |
|
10.03 |
(11) | PC I-Girder, Length |
35m; |
Height | 1.75m |
each |
S10.04 Pre-cast Concrete Piling
S10.04 (1) Description
This work shall consist of pre-cast reinforced concrete piling furnished and driven in accordance with these Specifications and in reasonably close conformity with the requirements on the Drawings or elsewhere in the Contract Documents.
S10.04 (2) Materials
(a) General
Pre-cast reinforced concrete piles shall be constructed in accordance with the details shown on the Drawings, of concrete Class C-3, mixed and placed in accordance with the provisions of Clause S10.01 of these Specifications. Reinforcement shall comply with the provisions of Clause S10.02 of these Specifications. Main reinforcing bars shall be supplied in one complete length and should this prove impractical separate lengths shall be effectively spliced by a method approved by the Engineer. The pile shall be so straight that a line stretched from tip to butt on any face will not be more than 1/1000 of the length of the pile from the face of the pile at any point.
(b) Formwork
Forms for pre-cast piles shall conform to the general requirements for concrete formwork as described in Clause S10.01 of these Specifications. Forms shall be accessible for compacting the concrete. Side forms may be removed at any time not less than 24 hours after completion of the placing of concrete but the entire pile shall remain supported for at least 7 days and shall not be subjected to any handling stress until the concrete has been in place for 21 days or such reduced time as the Engineer may decide as a result of tests.
(c) Reinforcement
Reinforcement shall be in accordance with the provisions set out in Clause S10.02 and positioned as shown on the Drawings.
(d) Casting
The piles shall be cast in a horizontal position. Special care shall be taken to place the concrete so as to produce a pile free from any air pockets, honeycomb or other defect.
Concrete shall be placed continuously and shall be compacted by vibrating or by other means satisfactory to the Engineer. The forms shall be slightly overfilled, the surplus concrete screeded off, and the top surface finished to a uniform, even texture similar to that produced by the forms.
(e) Finish
When removed from the forms piles shall present true, smooth, even surfaces free from any surface blemishes, and true to the dimensions shown on the Drawings.
(f) Curing
Concrete piles shall be covered with wet burlap immediately after placing is complete and shall be kept continuously wet for at least 7 days.
(g) Handling
When raising or transporting pre-cast concrete piles the Contractor shall provide slings and other equipment necessary to prevent any appreciable bending of the pile or cracking of the concrete. No concrete pile shall be lifted otherwise than by slinging from the lifting holes, the positions of which shall be submitted to and approved by the Engineer. Piles damaged in handling or driving shall be replaced. Concrete piles shall be so handled at all times to prevent breaking or chipping the edges.
Piles shall not be driven until 28 days have elapsed from the time of casting or such reduced time as the Engineer may decide as a result of tests.
S10.04 (3) Construction
(a) Preparation for Driving
(i) Caps – The heads of all concrete piles, when the nature of the driving is such as to unduly injure them, shall be protected by caps of approved design having a suitable cushion next to the pile head and fitting into a casing which in turn supports a timber shock block. No pile head will be held so firmly that the slight rotation of the pile normally occurring while the pile is being driven will be prevented.
(ii) Splicing piles – splices will be considered subject to specific approval by the Engineer as to their design, and location.
(b) Handling, Pitching and Driving
(i) General – The main setting out for the piles is to be completed prior to commencement of driving. Secondary or individual pile setting out is to be completed and agreed not less than 8 hours prior to commencing work on the piles concerned. All main setting out points, lines and stations are to be maintained safe and undisturbed until the work is complete.
Piles shall be pitched accurately in the positions and driven to the lines shown on the Drawings or fixed by the Engineer. Piles deflected from the vertical or proper line shall, where ordered by the Engineer, be withdrawn and re-pitched until the correction of the position or line of any pile will be permitted. Any pile damaged by reason of improper driving or driven out of its proper location or driven below the elevation fixed by the Drawings or by the Engineer, shall be corrected at the Contractor’s expense by one of the following methods approved by the Engineer for the pile in question:
- The pile shall be withdrawn and replaced by a new and if necessary longer pile. Any holes from which piles are withdrawn shall be packed with approved non-plastic material before re-driving takes place; or
- A second pile shall be driven adjacent to the defective or low pile.
All piles pushed up by the driving of adjacent piles or by any other cause shall be driven again.
(ii) Batter piles – Batter piles shall be driven accurately to the batter shown on the Drawings. The pile frame employed for the driving of the batter piles shall have leads capable of adjustment to the required angle. When piles have to be driven below the level of the bottom of the leads extension leads shall be provided except where the use of a follower is specifically permitted by the Engineer.
(iii) Driving equipment – Before any piling work is commenced the Contractor shall submit to the Engineer full details of the pile driving equipment and the method of carrying out the work he intends to use. All piles shall be provided with caps for driving as specified in Item (a) (i) above. For special types of piles, driving head mandrels, or other devices in accordance with these requirements shall be provided so that piles may be driven without damage.
Piles shall be driven with steam, air or diesel hammers, or a combination of hammers with water jets or gravity hammers.
In general:
- where diesel hammers are used for driving pre-cast concrete piles, the energy of the hammer shall numerically approximate one half of the weight of pile plus 4000kg.
- when gravity hammers are used for driving pre-cast concrete piles, the drop of the hammer shall not exceed 2.5 metres and the hammers shall have a weight of not less than half the weight of the pile. The fall shall be regulated so as to prevent injury to the pile.
- plant and equipment furnished for steam and air hammers shall have sufficient capacity to maintain, under working conditions, the pressure in the manner specified by the manufacturer. The boiler or tank shall be equipped with an accurate pressure gauge, and another gauge shall be supplied at the hammer intake.
(iv) Driving – Piles shall be supported in line and position with leads while being driven. Pile drive leads shall be constructed so as to afford freedom of movement of the hammer, and they shall be held firmly in position to ensure rigid lateral support to the pile during driving. Except where piles are driven through water, the leads shall be of sufficient length to make the use of a follower unnecessary, and shall be so designed as to permit the proper placing of batter piles. Once started driving shall be continuous. When water jets are considered by the Engineer to be necessary, the number of jets and the nozzle volume and pressure shall be sufficient to freely erode the material adjacent to the piling. The plant shall have at all times a pressure of at least 7 kilograms per square centimetre at two (2) centimetre jet nozzles. Before the required penetration is reached, the jets shall be shut off and the piles driven by hammer to final penetration.
A detailed accurate record of the driving of all piles shall be kept by the Engineer. The Contractor shall give every assistance to the Engineer to help him keep this record which will include the following : pile numbers, positions, types, sizes, actual lengths, dates driven, lengths in footings, penetration under final blows of the hammer, striking energy of the hammer, length cut off, and final pay lengths. No pile shall be driven near freshly placed concrete.
(v) Bearing values – Piles shall be driven to a bearing value of not less than that shown on the Drawings. The Engineer will specify the penetration and the Contractor shall drive the piles to the penetration specified, but if the Engineer is not satisfied that the desired bearing value has been attained, he may instruct action as for a defective pile as detailed in paragraph (3) (b) (i) of this section. Provided that the pile is not defective because of the failure of the Contractor to fulfil his obligations under this Contract, both the first pile and its replacement will be measured for payment under this Clause.
(vi) Cut off – Concrete piles shall be cut off as indicated on the Drawings or as directed by the Engineer at such elevation that the pile reinforcement will extend into and connect with the cap or footing.
Unless otherwise specified, pile cut-off length shall become the property of the Contractor and shall be disposed of beyond Government property limits and outside the limit of view from the roadway to the satisfaction of the Engineer.
Reinforced concrete piles may be cast the full length of the reinforcing bars, provided that the concrete is cut off to expose the steel as shown on the Drawings after the piles have been driven.
(c) Test Piles
The Engineer may order the execution of test piles as he may consider necessary to ascertain the type of the foundation for the project. The Contractor shall furnish and execute test piling at the locations designated by the Engineer.
The lengths of the piles shown on the Drawings are based on information obtained from previous site investigations. However, piles of different lengths may be required as directed by the Engineer. Before final pile lengths are settled, the Contractor shall construct to the lengths shown on the Drawings such pilot piles as may be found necessary. These piles shall be driven in the positions specified by the Engineer and the Contractor shall furnish the Engineer daily with a detailed record of the driving of pilot piles throughout the full depth of driving.
After attaining the approved set, driving shall be continued until the Engineer directs that it shall cease. Driving of test piles beyond the point at which the approved set is obtained will be called for to demonstrate that driving resistance continues to increase. The Contractor shall then furnish the remainder of the piles in the structure. In determining the lengths of piles the Contractor shall base his list on the lengths assumed to remain in the completed structure.
S10.04 (4) Method of Measurement
(a) Piles Furnished
The unit of measurement for payment for furnishing pre-cast reinforced concrete piles shall be in linear metres, furnished in compliance with the drawings and the Engineer’s instructions and the material requirements of these Specifications and stockpiled in good condition at the site of the work by the Contractor, and accepted by the Engineer.
No allowance will be made for the length of piles furnished by the Contractor to replace piles previously accepted by the Engineer that are subsequently lost or those that are damaged prior to completion of the Contract while in stockpile, or during handling or driving, and are ordered by the Engineer to be removed from the site of the work or disposed of otherwise. Where the Contractor elects to cast reinforced concrete piles the full length of the reinforcing bars as permitted in Clause S10.04 (3) (b) (vi) the length to be cut off due to such casting will not be measured for payment.
(b) Piles Driven
The quantities of driven pre-cast reinforced concrete piles to be paid for shall be the number of linear metres of piles actually driven and accepted. The pay lengths of the satisfactorily driven piles shall be measured from the tip to the cut-off. Lengths cut-off will not be measured for payment.
(c) Test Piles
The quantities of test piles as provided in Clause S10.04 (3) (c) to be paid for shall be the linear metres of test piles completed and accepted, whether they are executed inside or outside the foundation.
S10.04 (5) Basis of Payment
The work measured as provided above shall be paid for at the Contract unit price per linear metre for the particular pay items listed below. The rate shall constitute full compensation for all materials including reinforcement and shoes, equipment, hardware, furnishing, including formwork, etc., driving, jetting, cutting-off, welding, coupling and all related tools, rigs, cranes, boilers, hammers, jets, labour and other incidental equipment and work.
Payment for test piles, completed and accepted, shall be made as the linear metre of test piles for furnishing and driving a test pile of the size specified. When test piles are incorporated in the foundation no additional payment shall be made for the pile so utilized other than as for test pile.
No payment shall be made for unauthorized, defective, unsound or unsatisfactorily driven piles or for any costs incurred by the Contractor for such piles.
S10.05 Pretensioned Concrete Piling
Withdrawn.
S10.06 Steel Piling
Withdrawn.
S10.07 Cast-in-place Concrete Piling
S10.07 (1) Description
The work shall consist of cast-in-place concrete piles constructed by reverse circulation drilling methods, but during construction the Engineer may allow the use of alternative construction methods such as “Grab Type” hammers, steel casing, caisson or any other methods provided that the Contractor can demonstrate that these may be implemented without adverse effect on the work quality or approved schedule.
As part of the quality assurance control of the work non-destructive testing shall be carried out as directed. The scope shall also include static loading tests to verify the designed load.
In cases of doubt, the Engineer shall instruct further investigations of the completed piles. These further investigations shall include, but not be limited to, conducting pile driving analyzer testing in accordance with ASTM D 4945 – 00, Standard Test Method for High-Strain Dynamic Testing of Piles. Such instructions shall be issued pursuant to Clause G.49 (5) of the General Conditions of Contract.
S10.07 (2) Materials
Cast-in-place concrete piles shall be constructed, in accordance with the details shown on the Drawings, of concrete Class Y, mixed and placed in accordance with the provisions of Clause S10.01 of these Specifications.
Reinforcement shall comply with the provisions of Clause S10.02 of these Specifications.
S10.07 (3) Construction
(a) Excavation
Before excavation for permanent piles, the Contractor shall carry out trial excavation under the Engineer’s supervision. Generally, one trial excavation shall be carried out for each bridge location, each pile diameter and each subcontractor / construction team. Upon completion of trial excavation, the Contractor shall prepare and submit a report describing the work and proposing the preferred construction methods for the Engineer’s approval. The costs of trial excavation shall not be measured for payment and shall be included in the rates for payment for permanent piles.
The length of piles shall be as shown on the Drawings or as instructed by the Engineer. The methods used shall be such that the hole can be maintained vertical during all excavating operations.
Completed piles and existing structures very close to the pile excavation area shall be protected from the influence of ground movement and vibration and the Contractor’s proposals to ensure this shall be submitted to and approved by the Engineer, at least four weeks before the start of piling.
Excavated holes shall be protected from collapse by the provision of a head of water, bentonite slurry, temporary steel casing, segmental erected shields or other method approved by the Engineer for use at a particular location. If used, temporary steel casings shall be rigid and project above the ground surface for safety and to suit the equipment in use.
(b) drilling
Where bored pile drilling methods are adopted and bentonite slurry is used to support the surrounding ground, it shall be formed by a mix of good quality bentonite suspended in water, normally in the ratio of 8 – 17 kg of dry bentonite to100 litres of water, the actual ratio subject to final approval by the Engineer. The bentonite suspension shall satisfy the laboratory testing criteria below.
| TEST |
CRITERIA |
|
| 1. | Screening Oversize, 1000 mesh/sq.cm screen |
1% |
| 2. | Moisture Content |
15% |
| 3. | Liquidity Limit |
440% |
| 4. | Marsh Cone Viscosity 1500/1000 of 6% |
|
| suspension in distilled water |
40% |
|
| 5. | Setting of 6% Suspension in 24 hours. |
2% |
| 6. | Water Separation By Pressurised Filtration or |
|
| 450cc of the 6% suspension in 30 minutes at a |
|
|
| pressure of 7 kg/sq.cm |
18 cc |
|
| 7. | pH of Filtered Water. |
7 pH 9 |
| 8 | Cake Thickness of Filter-Pressure Filter |
2.5 mm |
(c) Preparation of Bentonite
The specifications of the bentonite used on site shall be as follows:
|
PROPERTY TO BE |
RANGE OF VALUES |
TEST METHOD |
|
|
MEASURED |
at 20 C° |
||
| 1. | Density | 1.10 gm/ml | Mud density balance |
| 2. | Viscosity | 30 – 90 sec. | Marsh Cone |
| 3. | pH value | 9.5 – 12 | pH Indicator Strips. |
| 4. | Shear Strength | 1.4 – 10 N/m2 | Shearometer |
The mixture shall be prepared using automatic high-powered mixers together with a component weight-metering device.
(d) Testing Bentonite
The drilling fluid shall be tested during piling operations. Once boring is completed, and before concreting, the fluid properties shall be measured taking samples at different depths.
The Contractor shall have approved testing facilities on site for tests of the specific gravity of the mixture, while an approved laboratory shall be used for testing the density, viscosity, pH and shear strength of the mixture.
The frequency of testing drilling fluid and the method and procedure of sampling shall be proposed by the Contractor as part of a method statement to be approved by the Engineer prior to the commencement of work.
Control tests shall be carried out on the bentonite suspension using suitable apparatus. The density of freshly mixed bentonite suspension shall be measured daily as a check on the quality of the suspension being formed. The measuring device shall be calibrated to read to within 0.01 gm/ml. Tests to determine density, viscosity, pH values and shear strength shall be applied to all bentonite being supplied to the drilled hole. For average soil conditions, the results of all testing shall generally be within the range of values stated in the above tables. The content of the fine sand component used must be less than 3% of the dry bentonite by weight. Testing shall be carried out until a consistent working pattern has been established, account being taken of the mixing process, any blending of freshly mixed bentonite suspension and previously used bentonite suspension and any process which may be used to remove impurities from a previously used bentonite suspension. When the results show consistent behaviour, the tests for shear strength and pH value may be discontinued, and tests to determine density and viscosity shall be carried out as agreed with the Engineer.
The Contractor shall submit to the Engineer for his approval the method proposed for sampling and checking of contaminated bentonite and for cleaning of the base of the excavation. In the event of a change in the established and approved working pattern, tests for shear strength shall be re-introduced.
(e) Temporary Casings
Temporary casings shall be used to maintain the stability of the pile excavation particularly at the top, which might otherwise collapse. Temporary casings shall be free of distortion and shall have a uniform cross-section not less than the specified pile diameter throughout each continuous length. During concreting the casings shall be free from internal projections and encrusted concrete, which might reduce the pile cross-section.
S10.07(4) Construction
(a) General Requirements
The Contractor shall submit to the Engineer for his approval particulars of the proposed materials and methods of constructing bored cast-in-place piles.
In particular if the Contractor proposes to use bentonite or other agents he shall:
* submit a certificate from the manufacturer of the bentonite powder showing the type, the manufacturers name, the date and place of manufacture and including details of the apparent viscosity range in centipoises and gel strength range in N/sq.mm for solids in water.
* give the characteristics of the bentonite slurry in a freshly mixed condition and in the excavation immediately before concreting.
* give the method of quality control, sampling, testing, mixing, storing, re-circulation removal of silt and sand, preventing spillages and disposal from the site.
* give the head of bentonite slurry, including calculations.
* method of placing the concrete by tremie.
* methods of cleaning all loose material from the bottom of the hole and demonstrating to the Engineer that removal has been accomplished. Consideration shall be given to cleaning in stages e.g. after excavating, after placing reinforcement and before concreting.
(b) Reinforcement
Reinforcement shall be positioned as shown on the Drawings. The connecting portions of main bars with hoops may be tack welded by arc fillet welding unless higher strength grades of reinforcement than those specified are in use, whence the connecting portions shall be securely tied.
During the placing of the reinforcement in the hole, the verticality and position of the reinforcement shall be carefully controlled to ensure design cover of concrete over the steel is maintained and to prevent damage to the walls or collapse of the excavation.
(c) Casting
Before casting commences all loose, disturbed or re-moulded soil shall be removed from the base of the pile using appropriate and approved methods, which may include air-lifting, and which shall be designed to clean while at the same time minimising further ground disturbance below the pile base and elsewhere.
Concrete shall be placed in one continuous operation by tremie tubes and shall be carried out in such a manner as to avoid segregation. The tip of the tremie shall generally be 2 m lower than the fresh concrete surface. The tremie pipe shall be clean and free from distortion or any matter, which may impede the smooth flow of concrete.
A sliding plug or similar barrier shall be placed within the tremie tube to prevent direct contact between the first charge of concrete and the water or bentonite.
The Contractor at his own expense shall remove any concrete placed above cut-off level to ensure satisfactory connection of the pile head to the pile cap or footing structure.
(d) Reporting
The Contractor shall furnish the Engineer daily with a detailed record of soils encountered during excavation and of all normal and abnormal procedures carried out during the construction of the piles.
S10.07 (5) Ultra-sonic and Static Load Testing of Piles
(a) Ultra-sonic Testing of Piles
Cast-in-place concrete shall be subject to non-destructive ultra-sonic testing. These non-destructive tests shall be carried out by a specialist firm accepted in advance by the Engineer. Before commencement of the work, the Contractor shall submit a detailed method statement of the procedures to be undertaken and calibration certificates of all testing apparatus for the Engineer’s approval.
The interpretation of the testing results shall be carried out by a competent person and an indication of the result of all testing shall be submitted to the Engineer immediately on completion of the testing for each pile. A full written report shall be submitted directly to the Engineer within 10 days of the test being carried out.
For the purposes of ultra-sonic testing, 50 mm (nominal) dia. Schedule 40 steel tubes shall be provided at every pile and these are to be equally spaced around the perimeter of the inner reinforcing steel spacer hoops. Three tubes shall be provided for cast-in-place concrete piles of dia. 1000mm, and four tubes shall be provided for cast-in-place concrete piles of dia. 1500mm and 2000mm.
The length of each tube shall be such as to extend from the bottom of the main reinforcement to at least 30mm above the top level of the temporary casing (to facilitate access). The bottom of the tube shall be permanently sealed while the top shall be provided with a screwed plug to prevent the ingress of any undesirable material.
It will be incumbent upon the Contractor to select carefully suitable tubes for straightness and to arrange his method of assembly of the tubes during placing of the pile reinforcements and concrete to avoid any possibility of introducing undesirable material into the tubes and to maintain the straightness after concrete casting. Care must also be taken to protect the tube assembly during extraction of the temporary casing and thereafter.
If it is found that for any reason it is not possible to lower the test probe down a tube, the Contractor will be responsible for making the tube good or for its replacement at his own expense.
Ultra-sonic tests shall be carried out within 7 days of concreting subject to the approval of the Engineer. For bored piles dia. 1000mm, three vertical full-length pile profiles shall be tested; and for bored piles dia. 1500mm and 2000mm, six vertical full-length profiles shall be tested
Upon completion of tests or whenever instructed by the Engineer, all the tubes shall be filled with an approved expanding grout capable of displacing the water contained within each tube while grout is progressively introduced starting from the bottom of the tube and working upwards.
The cost of providing, installing, and grouting all the steel tubes shall be included as part of the cost per linear metre of the bored pile.
If the ultra-sonic tests indicate any discontinuity or lack of homogeneity in the concrete, the Contractor may be instructed to perform core drilling for sampling and laboratory testing to determine whether the quality and bearing capacity of the concrete pile is impaired. The program for any such core drilling and testing shall be approved by the Engineer and all associated costs including grouting the core holes on completion shall be at the Contractor’s expense.
(d) Static Loading Test on Working Piles
In order to verify the designed load of the bored piles, static loading tests shall be carried out on two permanent bored piles of dia. 1000mm
Unless otherwise directed by the Engineer, the loading tests shall be conducted generally in accordance with ASTM D1143-81 (1994) and following the loading procedure in the table below.
Cycle |
Applied Load(% of DL) |
Min. Time of Holding Load |
Interval of Reading (Mins) |
|
Cycle 1 |
25 |
60 |
0-10-20-30-45-60 |
|
50 |
60 |
0-10-20-30-45-60 | |
|
75 |
60 |
0-10-20-30-45-60 | |
|
100 |
360 |
0-10-20-30-45-60-80-100-120-180-240-300-360 | |
|
75 |
10 |
0-10 | |
|
50 |
10 |
0-10 | |
|
25 |
10 |
0-10 | |
|
0 |
60 |
0-10-20-30-45-60 | |
|
Cycle 2 |
100 |
60 |
0-10-20-30-45-60 |
|
125 |
60 |
0-10-20-30-45-60 | |
|
150 |
60 |
0-10-20-30-45-60 | |
|
175 |
60 |
0-10-20-30-45-60 | |
|
200 (Proof Load) |
720 |
0-10-20-30-45-60-80-100-120-180-240-300-360-420-480-540-600-660-720 | |
|
175 |
10 |
0-10 | |
|
150 |
10 |
0-10 | |
|
125 |
10 |
0-10 | |
|
100 |
10 |
0-10 | |
|
0 |
60 |
0-10-20-30-45-60 |
Note: 1) Readings shall be taken just before and after change of loading.
2) Change of load shall be undertaken only if measured rate of settlement is less than 0.25 mm/hr.
3) Time between changes of load shall not exceed 2 hours except for Proof Loading.
The Contractor shall submit to the Engineer, within 48 hours of the completion of the pile test for each pile tested, a detailed record of testing and, in addition, graphs showing:
- - Load – Settlement relationship
- - Settlement – Time relationship.
- - Load – Settlement – Time relationship.
A full comprehensive written report shall be submitted to the Engineer within 10 working days for approval. After the completion of loading tests, all equipment and kentledge used shall be removed from the Site.
If the results of the load tests on working piles indicate that the designed load cannot be supported, the Engineer may instruct an additional pile to be tested. If this additional pile test confirms the earlier result, the Engineer may order such changes to the pile group as he considers necessary. In any case where an additional loading test or redesign of the pile group is required such expense will be reimbursed to the Contractor provided that the additional work and redesign have not arisen through any default on the part of the Contractor.
S10.07 (6) Method of Measurement
Cast-In-Place Concrete Piles
The quantity of cast-in-place concrete piles to be paid for will be the actual number of linear metres measured from the cut off level to the base of the pile as shown on the Drawings and as confirmed by actual measurement without any allowance for over-excavation.
S10.07 (7) Basis of Payment
The work measured as provided above shall be paid for at the Contract price per unit of measurement for the pay items listed below.
The payment for cast-in-place pile shall be full compensation for construction of the piles including protection of existing piles and structures, all materials for completion of the pile and for all labour, tools, equipment, hauling, handling, jetting, jointing, cutting and all other incidental and temporary works connected therewith.
The payment for ultra-sonic testing and static loading tests on working piles will be made on a unit item basis regardless of pile diameter as described below. The payment shall be full compensation for the tests and for all labour, tools, equipment, hauling, handling, disposing, monitoring, recording, reporting and all incidentals necessary for the satisfactory completion of the work. If the Engineer instructs that the load tests shall be carried out on bored piles constructed under water (canal, river, etc.), the payment under these items shall also be full compensation for all costs incurred in relation to this work including temporary works and maintenance of navigation.
Pay Item No. Name Unit of Measurement
10.07 (1) Cast-In-Place Concrete Pile, D = 1000mm linear metre
10.07 (2) Cast-In-Place Concrete Pile, D = 1500mm linear metre
10.07 (3) Cast-In-Place Concrete Pile, D = 2000mm linear metre
10.07 (4) Ultra-Sonic Tests Each
10.07 (5) Static Loading Tests Each
S10.08 Test Drilling
S10.08 (1) Description
This work shall consist of test drilling for the investigation of structural sites and soft ground as directed by the Engineer.
S10.08 (2) Test Bores
(a) General
When testing is required the Contractor shall take several test bores at each site to get the exact soil profile or as otherwise directed by the Engineer.
(b) Depth of Bores
The depth of test bores shall be instructed by the Engineer but shall generally be as follows:
Structural Drilling: to confirm the bearing stratum as proven by five metres of SPT results > 50.
Soft Soil Drilling: to confirm the absence of soft soil as shown by either a two metre strata with SPT results greater than 50, or a five metre strata with SPT results greater than those given in paragraph (f). Maximum depth of drilling will be 25 metres unless the Engineer instructs that drilling should continue to a greater depth.
(c) Samples
The Contractor shall be required to drill and obtain samples including undisturbed thin-walled samples for inspection by the Engineer and for subsequent use in laboratory testing. Undisturbed soil sampling shall be carried out by using thin-walled metal tube in conformity with AASHTO T207. In rock core drilling the full core shall be recovered and stored in core boxes for inspection by the Engineer.
(d) Tests Required on Bores.
Standard penetration tests ( ASTM-D-1586 ) shall be taken at 1.0 metre intervals or at each change of strata whichever is lesser. The Contractor shall take one soil sample immediately after each individual SPT test, maintain the samples until their disposal is approved by the Engineer, and shall submit those to the Engineer on request. The static ground water level shall be recorded for each hole. Further testing will be required as follows:
TEST TESTING REQUIREMENTS
1. Natural Water Content ( ASTM-D-2216 ) All Samples
2. Grain Size Analysis (ASTM-D-422 ) All Samples
3. Liquid Limit Test ( ASTM-D-423 ) All Samples
4. Plastic Limit Test ( ASTM-D-424 ) All Samples
5. Specific Gravity ( ASTM-D-854 ) All Samples
6. Wet Density Test ( Calliper method ) Undisturbed Samples
7. Unconfined Compression ( ASTM-D-2166 ) Undisturbed Samples
8. Tri-axial (UU) Compression ( ASTM-D-2850 ) Undisturbed Samples
9. Consolidation Test ( ASTM-D-2435 ) Undisturbed Samples.
10. Lateral Loading Test ( ASTM-D-4719 ) In-Situ test ( these will be at depths of 5m or 10 m or as instructed by the Engineer )
The location of sampling and the type of sample / test required will be instructed by the Engineer. Test results from the soft soil boring will be used in the control of embankment filling and where necessary the design of a system of vertical soil drains to accelerate the rate of consolidation in such areas. The Engineer will call for more extensive testing than described above at any site should he find that the information obtained by the Contractor is not adequate enough to determine the necessary parameters to allow the intent of the design to proceed.
(e) Logging of All Bores and Reporting
If so requested by the Engineer, the Contractor shall supply on the working day following completion of the bore the following information:
1) Structure name 2) Bore exact position and code number
3) Reduced level of top of bore 4) Date and time of boring
5) Diameter of bore 6) Depth to which bore was cased
7) Type of plant used 8) Depth to base of each stratum
9) Description of strata 10) Depth and results of in-situ tests
11) Static water level 12) Remarks
Irrespective of any interim data information supplied as per the above, at the end of the work on test drilling the Contractor shall submit the original and two copies of a comprehensive report covering all the services rendered under this clause. The report will include the above data, the laboratory test results and any other information that the Contractor considers relevant to this work.
- (f) Criteria for Determining Soft Ground These shall be as follows:
|
PEAT OR CLAYEY SOIL |
SANDY |
||
| Thickness < 10m | Thickness > 10 m |
SOIL |
|
| N -Value by SPT |
SPT < 4 |
SPT < 6 |
SPT < 10 |
| Unconfined Compression Strength qu (kgf/cm2) |
qu < 0.6 |
qu < 0.6 |
____ |
|
Cone Coefficient by Dutch Cone Test: qc (kgf/cm2) |
qc < 8 |
qc < 12 |
qc < 40 |
S10.08 (3) Additional Site Tests
Withdrawn
S10.08 (4) Method of Measurement
The work of Test Drilling and Dutch Cone testing will be measured for payment purposes by the lengths of each hole drilled or tested. The measurement for the Insitu Lateral Load and Vane Shear tests will be based on the number of tests conducted irrespective of their depth. The sampling and testing will be measured by the number and type of sample as instructed by the Engineer, with Disturbed and Undisturbed samples being measured and paid for separately. No measurement will be made of the soil samples which are collected immediately after each SPT test and which are stored by the Contractor.
S10.08 (5) Basis of Payment
Payment will be made on the quantities as measured above and at the rates shown in the Bid Schedule. The price and payment for test drilling shall include full compensation for all mobilization, drilling, casing (if necessary), SPT testing and taking / maintaining soil samples at the SPT points, reporting, and for all other costs not specifically mentioned below.
The price and payment for Sample Testing shall include full compensation for all sample extraction and preparation, transporting to the laboratory, testing, recording and presenting the results and storing the samples until their disposal is approved by the Engineer.
The price and payment for below-mentioned item shall be full compensation for all labour, equipment, tools and incidentals necessary for the satisfactory completion of the work
Pay Item No. Name Unit of Measurement
10.08(1) Test Drilling on land (general) linear metre
10.08(2) Test Drilling over water (general) linear metre
10.08(3) Withdrawn linear metre
10.08(4) Sample Testing (Disturbed) each
10.08(5) Sample Testing (Undisturbed) each
10.08(6) Insitu Lateral Load Test each
10.08(7) Dutch Cone Testing linear metre
10.08(8) Vane Shear Testing each
S10.09 Bridge Railing
S10.09 (1) Description
This work shall consist of furnishing, fabricating and erecting steel pipe railings, aluminium railings for bridges, incidental structures, all as indicated on the Drawings and required by these Specifications and as directed by the Engineer.
S10.09 (2) Materials
(a) Materials shall conform to the requirements of :
JIS G 3101 : Rolled Steel for General Structures
JIS G 3452 : Carbon Steel Pipes for Ordinary Piping
JIS G 3444 : Carbon Steel Tubes for General Structural Purposes
JIS G 3466 : Carbon Steel Square Pipes for General Structural Purposes
JIS G 3532 : Low Carbon Steel Wires
JIS H 4040 : Aluminium and Aluminium Alloy Rods, Bars, Wires
JIS G 4303 : Stainless Steel Bars
(b) Mortar and grout shall conform to the provisions of Clause S12.04 of these Specifications. Parapets shall be constructed, in accordance with the details shown on the Drawings.
(c) All steel railing and fittings shall be hot-dip galvanised unless otherwise specified, in accordance with the requirements of Clause S12.18 of these Specifications. All aluminium alloy shall be coated in accordance with the Specifications of JIS H 8601. Galvanised areas damaged by welding or other site works shall be cleaned and given 3 coats of an approved zinc based paint, to the satisfaction of the Engineer.
(d) Where painting is required, it shall be in accordance with the requirements of Clause S12.18 of these Specifications.
S10.09 (3) Construction
(a) Pipe railings, fittings and incidental parts shall be carefully handled and stored on blocking, racks or platforms so as not to be in contact with the ground and shall be protected from corrosion. Materials shall be kept free from dirt, oil, grease and other foreign matter. Surfaces to be painted shall be carefully protected both in the shop and in the field. Threads shall be carefully protected from damage.
(b) Railings shall be carefully constructed true to line and grade as shown on the Drawings, and no construction shall be commenced before the inspection and approval by the Engineer, and before all centres, supports, and falsework or staging of bridge superstructure have been removed.
(c) The component parts of pipe railings shall be connected with threaded screws unless otherwise specified on the Drawings. Fitting for railings on slopes shall be levelled to fit the required grades. Screw thread fittings shall be coated with red lead and oil, and the threads shall engage for a minimum length of 2 centimetres. Expansion shall be provided by
omitting threads on one side of fittings at designated posts. Where the rails are continuous through two or more posts threads may be omitted between the rails and the fitting, but the rail must be pinned at each post. Where welding of component parts is permitted, the details must be in accordance with the Drawings or as approved by the Engineer.
(d) The Contractor shall provide for the erection of pipe railing by suitable fabrication in the shop. Where railing is fitted between concrete posts, provision shall be made to allow the installation of same.
Railings shall be fabricated and erected as indicated on the Drawings, and rails shall be parallel to the grade of the road. Posts shall be set truly vertical unless otherwise instructed by the Engineer.
All exposed surfaces shall be thoroughly cleaned in an approved manner as a final operation under this project.
(e) The Contractor shall furnish for the approval of the Engineer working drawings for the particular type of bridge railing specified to be installed.
S10.09 (4) Method of Measurement
The quantities of metal bridge railing to be paid for shall be the number of linear metres of railing and completed and accepted in accordance with the Drawings, these Specifications, and as directed by the Engineer.
S10.09 (5) Basis of Payment
The work measured as provided above shall be paid for at the Contract unit price per linear metre of bridge railing. The price and payment shall be full compensation for furnishing bridge railing including delivery, erection and finishing, and for all labour, equipment, tools and incidentals necessary for the satisfactory completion of the work.
Pay Item No. Name Unit of Measurement
10.09(1) Bridge Railing, Type A linear metre
10.09(2) Bridge Railing, Type B linear metre
S10.10 Bridge Expansion Joints
S10.10 (1) Description
This work shall consist of the supply and installation of expansion joints in accordance with and at the locations shown in the Drawings.
S10.10 (2) Submittals
A sample of any expansion joint material that the Contractor proposes to use in the work, together with a statement as to its source and test data giving its properties shall be submitted to the Engineer and approved by him before placing any order for the materials. The Contractor shall submit a certificate by the manufacturer to the Engineer for approval before furnishing the material.
S10.10(3) Materials
(a) Material for rubber expansion joints shall comply with the following specification requirements:
(i) Poly-chloroprene Rubber (e.g. “Neoprene” )
Tensile strength ASTM D412 : ³ 12.40 MPa
Elongation @ Break Point ASTM D412 : ³ 400%
Hardness Type A Durometer ASTM D 2240 : 45 + 5
Compressive permanent strain ASTM D395
(Method B at 70oC, 22 hours) : £ 20%
(ii) Bonding Agent for Rubber
Specific gravity JIS K 6911 : 1.20 + 0.10
Viscosity JIS K 6838 : pasty condition
Peel Adhesive strength JIS K 6854 : ³ 3 kg/cm2
(180º peel adhesive strength
between resin mortar and vulcanised rubber)
Tensile strength JIS K 6301 : ³ 200%
Elongation JIS K 6301 : ³ 200%
(b) Epoxy Concrete
The mixture of epoxy concrete shall include a two-component epoxy resin and silica sand.
The mixture shall meet or exceed the following ASTM requirements for C881-78 Type 1, Grade 2, Class B and C epoxies.
Density ( at 20ºC, 7 days) : 2.0 kg/l (approx.)
Bonding strength ( at 20ºC, 1 day)
to i) Concrete : ³ 3.5 N/mm2
ii) Steel : ³ 20 N/mm2
Tensile Strength : 15 – 20 N/mm2
Flexural Strength : 30 – 35 N/mm2
Compressive strength : 80 – 90 N/mm2
Compressive Young’s modulus : ³ 19,000 N/mm2
(c) Sealant Material
Where required 2-part poly-sulphide sealant material shall be in accordance with JIS K 6301 with the following parameters.
Elongation : = 500%
Tensile strength: : = 8 kg/cm2
S10.10 (4) Construction
(a) Storage and Preparation
Expansion joint material delivered to the bridge site shall be stored under cover on platforms above the surface of the ground. It shall be protected at all times from damage, and when placed it shall be free from dirt, oil, grease or other foreign substance. Pre-moulded material shall be used in as large a piece as possible. The material shall be cut to a clean, true edge with a sharp tool. Rough or ragged edges will not be permitted. Jointing of adjacent pieces shall be in accordance with the manufacturers’ instructions.
(b) Installation
(i) General – Expansion joints shall be shaped to the section, and of a type of material as shown on the Drawings or approved by the Engineer. The size of the gap shall be compatible with the mean bridge temperature at the time of installation. This temperature shall be determined in accordance with arrangements agreed with the Engineer.
The position of all bolts cast into concrete and all holes shall be accurately determined from templates. The mixing, application and curing of all proprietary materials shall comply with the manufacturer’s requirements.
All joints shall be constructed according to physical details shown on the Drawings or as directed by the Engineer, and strictly in accordance with the manufacturer’s recommendations.
(ii) Placing of epoxy mortar – If required by the Engineer placing of epoxy mortar shall be executed in 2 (two) stages. Bottom-layer mortar shall be placed after a primer (epoxy binder) has been applied to the slab surface and side section of the pavement and the mortar compacted by means of a vibrator machine to a thickness of 2.0 cm from the pavement level. The top-layer of mortar shall be placed after the embedding of Fibre Reinforced Plastic. The top layer shall be compacted with a vibrator to level with the surface pavement. Rough finishing shall be carried out with a wooden trowel and final finishing with a metallic trowel.
(iii) Prevention of damage – During the placing and hardening of concrete or mortar under expansion joint components, relative movement shall be prevented between them and the supports to which they are being fixed.
When one half of the joint is being set, the other half shall be completely free from longitudinal restraint. In particular where strongbacks or templates are used to locate the two sides of a joint they shall not be fixed simultaneously to both sides. Screw threads shall be kept clean and free from rust.
Ramps shall be provided and maintained to protect all expansion joints from vehicular loading. Vehicles shall cross the joints only by means of the ramps until the Engineer permits their removal.
(iv) Time of installation – Setting of expansion joints shall be done after pavement works on the bridge are finished.
S10.10 (5) Method of Measurement
The quantities to be paid for shall be:
The actual number of linear metres of pre-formed expansion joints completed in place in accordance with the Drawings. Sealant and back up forms of foamed polystyrene or asphalt impregnated fibre board material used in adjacent curbs and parapet walls will not be measured separately for payment.
S10.10 (6) Basis of Payment
The quantity, measured as specified above, shall be paid for at the Contract price per unit of measurement, respectively, for each of the particular pay items listed below, which price and payment shall constitute full compensation for all cutting and excavation of pavement, formation of construction joint with existing concrete and for all labour and equipment, furnishing of materials including epoxy concrete, epoxy mortar, fibre reinforced plastic, reinforcement and concrete, fabricating, transporting, painting, setting expansion joints, and for other incidentals. Payment for pre-formed expansion joints will be deemed to include the cost of sealant used in adjacent works and parapets.
Pay Item No. Name Unit of Measurement
10.10 (1) Expansion Joint, Type A linear metre
10.10 (2) Expansion Joint, Type B linear metre
10.10 (3) Expansion Joint, Type C linear metre
10.10 (4) Expansion Joint, Type D linear metre
S10.11 Bridge Bearings
S10.11 (1) Description
This work shall consist of furnishing and installing bearing devices for bridge superstructures as indicated on the Drawings, or as directed by the Engineer.
Whenever complete details for bearings and their anchorages are not shown on the Drawings, the Contractor shall prepare and submit working drawings for the bearings together with manufacturer’s brochure. Such drawings shall show all details of the bearing devices and of the materials proposed for use and must be approved by the Engineer before fabrication of the bearings is begun. Such approval shall not relieve the Contractor of any responsibility under the Contract.
The Contractor shall submit a certificate by the manufacturer to the Engineer for approval prior to furnishing bearing devices.
S10.11 (2) Materials
(a) Bearing Shoes
Material for elastomeric type bearing shoes shall conform to the following:
| ITEM | UNIT |
ELASTOMERIC MATERIAL |
TEST METHOD and |
|||||||||
|
Poly-chloroprene |
Natural Rubber |
CONDITION |
||||||||||
| STATIC SHEARING | JISK 6301-13 | |||||||||||
| ELASTICITY MODULUS | kgf /cm2 | 8±1 | 10±1 | 12±1.2 | 8±1 | 10±1 | 12±1.2 | 13.5±1.3 | JISK 6301Formula | |||
| HARDNESS | Degree | 50±5 | 60±5 | 65±5 | 50±1 | 60±5 |
65±5 |
JISK 6301-5 | ||||
| ELONGATION |
% |
> 440 |
>650 |
>600 |
>550 |
JISK 6301-3 | ||||||
| TENSILE Str. | kgf /cm2 |
>150 |
JISK 6301-3 | |||||||||
| FATI | STRENGTH VARIATION for 25% Elong. |
% |
-10 <% <+10 |
-10 <% < +30 |
JISK 6301-3JISK 6301-13 | |||||||
| GUE | ELONGATION |
% |
>50 |
JISK 6301-3JISK 6301-13 | ||||||||
| PERM.COMPRSTRAIN |
% |
<35 |
<25 |
JISK 6301-10 | ||||||||
| OZONE RESIST. |
- |
No crack to be observed by naked eye |
JISK 6301-16 | |||||||||
| Wt. VARIATION DUE TO MOISTURE ABSORPTION |
% |
< 10%
|
JISK 6911-5 | |||||||||
| LOW TEMP. RESISTANCE | Degree |
£ – 30oC |
JISK 6301-14 | |||||||||
| RESISTANCE TO STRIPPING | kgf /cm2 |
³ 7 |
JISK6301-8.3JISK 6301-13 | |||||||||
(b) PTFE Sliding Type Bearing Shoes
Physical Properties of PTFE (Polytetrafluoroethylene)
|
ITEM |
UNIT |
TEST VALUE |
TEST METHOD
USED |
SPECIFIED VAUE |
| SPECIFIC WEIGHT |
|
2.18 |
JISK 6888 |
2.10-2.40 |
| MELTING POINT |
o C |
327 |
JISK 6888 |
327±10 |
| TENSILE STRENGTH |
kg/cm2 |
315 |
JISK 6888 |
140 |
| ELONGATION |
% |
400 |
JISK 6888 |
100 |
| HARDNESS |
o SHORE |
55 |
ASTM D 2240 |
55-70 |
| COMPRESSIVE CREEP(24 Hour Permanent Deformation) |
% |
7.9 |
ASTM D 62123±2oC 140 kg/ cm2 |
8 |
| FRICTION COEFFICIENT |
0.063 |
SUS 316 ( as against SUS 916) |
0.08 |
Complete - – bearing devices such as Pot Bearing must be shown on the Contractor’s working drawings.
- (c) Bearing Pads
Bearing pads shall consist of alternative laminations of elastomer and metal bonded together, as shown on the drawings, and shall conform to the following requirements and the minimum values for the metal laminates specified below:
Bearing stress : 15 – 80 kg/cm2
Compression strain : 15% max.
Horizontal deformation : 50% max.
BEARING PAD BONDED METAL REINFORCEMENT ( STRAIN CONTROL)
|
ITEM |
UNIT |
SUS 304 |
SS 400 |
||
|
|
SPEC.VALUE |
TEST METHOD |
SPEC. VALUE | TEST METHOD | |
| TENSILE STRENGTH |
N/mm2 |
>520 |
>400 |
||
| ELONGATION |
% |
>40 |
JIS Z 2241 |
>21 |
JIS G 3101 |
| YEILD POINT OR | |||||
| ULT.STRENGTH |
N/mm2 |
>205 |
>245 |
||
(d) Allowable Values for Elastic Bearings.
|
CHECK FORMULA |
ALLOWABLE VALUES |
REMARK |
|||||
| MAXIMUM |
s max. £ s max,a |
s max, a = 80 kgf/cm2 | Effective bearingarea considered. | ||||
| COMPRESSIVE STRESS | MINIMUM | s min. ³ s min, a | smin. = 15 kgf/cm2 | ||||
| STRESS FLUCTUATION |
Ds £ Dsa |
Dsa = 50 kgf/cm2 | |||||
| SHEARING | @ NORMAL |
gs £ ga |
ga = 70% | ||||
| STRAIN | @ EARTHQUAKE |
gse £ gae |
gae = 150% | ||||
|
BUCKLING
|
a, b ³ 5 x åte and a, b ³ 10 cm |
||||||
| ROTATION | åae x a/2 < d | ||||||
| LOCAL SHEARING STRAIN | g = gc + gs + grg £ gta | gta = _gu _ 1.5 | To be checked @ normal condition. | ||||
| STRESS ON REINFORCING STEEL | ss £ ssa | SM490 in accordance with JISG 3106. | |||||
| SPRING CONSTANTS (Compressive and Shearing to conform to design ) | JISK 6835 | ||||||
| Where: | Ds = Dsmax. - Dsmin | ||||||
| a = | Longitudinal effective length of bearing shoe, | ||||||
| b = | Transverse effective width of bearing shoe, | ||||||
| åte | :total thickness of the elastomer rubber, | ||||||
| åae |  verall rotation (radians) of the total rubber thickness, |
||||||
| d | :compressive stain under vertical load with bearing effective area, | ||||||
| gc | :local shearing strain under vertical load, | ||||||
| gs | :local shearing strain due to shearing deformation, | ||||||
| gr | :local shearing strain due to rotation, | ||||||
| gu | :shearing strain at rupture | ||||||
S10.11 (3) Construction
(a) Bearing Shoes and Stoppers.
(i) Bearings, bearing shoes and stoppers shall be accurately set in their specified positions during construction of substructure and superstructure members.
(ii) If the Engineer gives approval for bearing shoes and stoppers to be set after construction of the sub-structure members, block outs or boxing out of the piers or abutments shall be of such dimensions as to permit adequate horizontal and vertical positioning of the bearing shoes or stoppers prior to grouting of their anchor bars. Only a high-strength non-shrink mortar shall then be used to fill the block-outs and any space between the substructure and the underneath of the bearing shoe or stopper.
(iii) In placing any anchor bolts – reference is made to Clause S10.01 (4)(f)(xi) should this, in the opinion of the Engineer, be applicable.
(b) Bearing Pads
The bearing pads shall be installed in the appropriate setting as directed by the Engineer or shown on the Drawings.
When they are set on thin beds of cement mortar, the mortar shall be cured and allowed to develop sufficient strength before the beams are erected.
The bearing pads shall be maintained in their correct position during the placing of the beams. After the beam has been completed, each bearing and the area around it shall be left clean.
S10.11 (4) Method of Measurement
The quantities of bearing devices shall be measured by the number of each type completed in place and accepted.
S10.11 (5) Basis of Payment
The work measured as provided above will be paid for at the Contract unit price respectively. The payment shall consist of full compensation for furnishing, fabricating, transporting, painting and placing all materials including all labour, tools, equipment, and incidentals necessary to complete the work prescribed. Details of necessary accessories are shown on the Drawings, and include anchor bar and cap, and reinforcement, etc should these items be applicable.
Pay Item No. Name Unit of Measurement
10.11 (1) A Elastomeric Bearing Shoe,Type A 175t each
10.11 (1) B Elastomeric Bearing Shoe,Type B 300t each
10.11 (1) C Elastomeric Bearing Shoe,Type C 650t each
10.11 (1) D Elastomeric Bearing Shoe,Type D 800t each
10.11 (1) E Elastomeric Bearing Shoe,Type E 850t each
10.11 (2) MA Pot Bearing, Type MA each
10.11 (2) MB Pot Bearing, Type MB each
10.11 (2) MC Pot Bearing, Type MC each
10.11 (2) FC Pot Bearing, Type FC each
10.11 (2) FD Pot Bearing, Type FD each
10.11 (3) A1 Elastomeric Bearing Pad, Type A1 each
10.11 (3) A2 Elastomeric Bearing Pad, Type A2 each
10.11 (3) B Elastomeric Bearing Pad, Type B each
10.11 (3) C Elastomeric Bearing Pad, Type C each
10.11 (3) D Elastomeric Bearing Pad, Type D each
10.11 (3) E1 Elastomeric Bearing Pad, Type E1 each
10.11 (3) E2 Elastomeric Bearing Pad, Type E2 each
10.11 (3) F Elastomeric Bearing Pad, Type F each
10.11 (3) G Elastomeric Bearing Pad, Type G each
10.11 (3) H Elastomeric Bearing Pad, Type H each
S10.12 Other Incidental Bridge Facilities
S10.12 (1) Description
This work shall consist of the furnishing and installation of drainage, waterproofing and other incidental bridge requirements. All work shall be done in strict accordance with the Drawings and these Specifications and as directed by the Engineer.
S10.12 (2) Materials
- (a) Drainpipe material shall conform to the requirements of (un-plasticized Poly-vinyl Chloride Pipes) AASHTO M267, deck drain material shall conform to the requirements of JIS G 5101 (Carbon Steel Castings), JIS G 5501 (Grey Iron Castings), and JIS G 3101 (Rolled Steel for General Structures : SS41). Where appropriate, all metal deck drain material including support brackets shall be zinc coated (hot-dip galvanised).
- (b) The Bridge Deck Waterproofing to be used shall take the form of a hot applied polyester- reinforced elastomeric-bitumen membrane with a particular application to the waterproofing of concrete surfaces. The proposed material shall be capable of retaining its bonding to the underlying concrete surface while maintaining its stability during the application and compaction of the asphaltic concrete overlay at 160 C°. Where recommended by the waterproofing manufacturer, a bituminous tack coat shall be applied to the waterproofing without additional payment.
- (c) Pre-cast Reinforced Concrete Plate shall be formed as shown on the Drawings and in accordance with the appropriate clauses of this Specification.
S10.12 (3) Construction
Drainage Facilities
Drainpipes, catch basin and deck drains that are to be encased in concrete shall be installed by the Contractor as indicated on the Drawings. Other pipes and drainage boxes shall be fixed as indicated on the Drawings or as directed by the Engineer.
Bridge Deck Waterproofing
This shall be a proprietary material to be approved by the Engineer and all installation details shall be in accordance with the manufacturer’s recommendations
Pre-cast Items
All works shall be carried out in accordance with the details shown on the Drawings and give in the relevant sections of these Specifications.
S10.12 (4) Method of Measurement
The quantities of drain pipe to be paid for will be the number of linear metres measured along the central lines of pipe runs and no extra measurement will be made for bends, fittings, joints, etc.
The quantities of deck drain boxes to be paid for shall be measured by the number of each type, completed in place and accepted.
The quantity of bridge deck waterproofing material to be paid for will be the actual number of square metres of finished bridge deck treated in accordance with the Drawings and the Engineer’s instructions. No extra measurement will be allowed for laps or wastage.
Pre-cast Reinforced Concrete Plate shall be measured by the number of square metres installed at the site in accordance with the drawings.
S10.12 (5) Basis of Payment
The quantities, measured as specified above, will be paid for at the Contract unit price per linear metre of drain pipes, per number of deck drain boxes and per square metre of bridge deck waterproofing.
Payment for drainpipe and deck drain will be deemed to include for all fittings and supports necessary to install the drains in accordance with the details shown on the Drawings.
The prices and payment for the above items shall be considered full compensation for labour, tools and equipment, furnishing of materials, fabricating, transporting, and setting of each item and all other incidental works connected therewith.
Pay Item No. Name Unit of Measurement
10.12 (1) PVC Drain Pipe, D=15cm linear metre
10.12 (2) PVC Drain Pipe, D=20cm linear metre
10.12 (3) Deck Drain Box each
10.12 (4) Precast RC Plate, Type A square metre
10.12 (5) Precast RC Plate, Type B square metre
10.12 (6) Bridge Deck Waterproofing, Type A square metre
S10.13 Box Culvert
S10.13 (1) Description
This work shall consist of the construction of box culverts and associated wing-walls for multi-purposes in accordance with these Specifications, the specifications for other work items involved, all in conformity with the lanes, grades and dimensions instructed by the Engineer. The technical box culverts (technical tunnel) shall not be covered by this specification but following Clause S10.14.
The cost of working in executing the work of this section will be deemed to be included in the unit price for the pay item being installed or constructed.
S10.13 (2) Survey and Drawings
Types and characteristics of the box culverts and associated wing- walls shown on the following Table and the Drawings, and their estimated total quantities entered in the Bid Schedule are not to be taken as final.
|
Type |
B x H (m) |
Usage Purpose |
|
A |
4.0 x 2.7 |
Underpass Pedestrian (P) |
|
B |
5.0 x 3.7 |
Underpass Vehicle (V) |
|
C |
8.0 x 3.7 |
Underpass Vehicle (V) |
|
D |
9.0 x 5.0 |
Underpass Vehicle (V) |
|
E |
9.5 x 5.0 |
Underpass Vehicle (V) |
|
F |
2.0 x 2.0 |
Water Drainage (W) |
|
G |
4.0 x 2.5 |
Water Drainage (W) |
To assist the Engineer in his review of the contract drawings, the Contractor will undertake a survey of all sites to determine the location, culvert size, formation level and entering the Site.
On the basis of the results of this survey the final types, lanes, characteristics and quantities will be decided by the Engineer, who will inform the Contractor of them in writing in due time in relation to approved schedule of work submitted by the Contractor. The cost of this survey will be deemed to be included in the various pay items of this Works.
S10.13 (3) Sequence of Works
In area where significant settlement is expected below new embankments, the Engineer may instruct that work on such embankments be delayed until the settlement is substantially completed. This delay shall be considered by the Contractor when preparing his schedule of site works, temporary drains for pre-loading and soft soil treatment shall be provided as necessary. Additional or special conditions relating to this matter will be given by the Engineer if required. The Contractor shall be at all times so schedule, therefore to avoid the delay and damage to works in course of construction the Contractor shall provide in due time adequate means of protection, including securing detours for passing vehicles and pedestrians and so on.
S10.13 (4) Materials
All materials shall comply with the relevant requirements of these Specifications and details shall be as shown on the Drawings.
S10.13 (5) Construction
- a) Excavation
Prior to starting excavation the Contractor shall take all necessary measures to keep the excavation free from free-surface water or surface water from pre-loading and soft soil treatment.
Except as otherwise instructed by the Engineer, in areas of fill, filling shall be completed pre-loading and soft soil treatment, before excavation begins. All excavation shall be carried out so as to minimize damage to existing surfaces.
Excavated materials not required for back-filling shall be dealt with in accordance with Section 4 of these Specifications.
Soft spots in the bottom of box culvert excavation shall be removed and the resulting void immediately back-filled with Granular Backfill as stipulated in Clause S4.08. When the Engineer instructs this additional treatment it will be paid for under the relevant clauses of these Specifications.
Where the Engineer considers that soft spots are due to the Contractor’s failure to fulfil his obligations under any clause of these Specifications then the Contractor shall, at his own expense, undertake the additional excavation and replacement with Granular Backfill to the satisfaction of the Engineer.
Any suitable material below the level of the box culvert bed, which is removed unnecessarily, shall be replaced at the Contractor’s expense with Granular Backfill in accordance with Clause S4.08 of these Specifications.
b) Bedding Finishing
Excavation shall be executed after pre-loading and soft soil treatment until the true line and level as directed by the Engineer. Then blinding stone shall be laid uniformly and justly, and compacted deliberately to the satisfaction of the Engineer.
After the above treatment, lean concrete shall be placed as shown on the Drawings so as to install the form of concrete correctly for constructing box culvert.
c) Backfilling and Reinstatement
Backfilling shall not commence until in the opinion of the Engineer, the concrete has achieved sufficient strength. Backfilling shall be carried out in accordance with the requirements of Clauses S4.05, except that the material used for backfill around and above the box culvert for a minimum distance of 50cm shall be sand in place or excavated material. Where insufficient suitable material is available, surplus material from any other excavation shall be used. On completion of backfilling, the area excavated shall be reinstated to its original condition but the Engineer may waive or modify this requirement if the area is to be overlaid or reconstructed under other Clauses of this Contract.
S10.13 (6) Method of Measurement
The quantity of reinforced concrete box culvert to be paid for, shall be the number of linear metres measured along the centre-line of the box culvert, between the outside faces of box culvert, including construction of wing-walls for each type of box culvert as indicated on the Drawings.
S10.13 (7) Basis of Payment
The price and payment will be full compensation for furnishing and installing each type of box culvert and for providing all related facilities as shown on the Drawings including reinforcement and for all labour, tools, equipment and incidentals necessary to complete the work as described in this Specification except excavation and backfilling for which payment shall be considered to be covered as stipulated in SECTION 5 – STRUCTURE EXCAVATION.
Payment for pavement and lighting inside box culverts shall not be included in these items but included in other relevant items provided in these specifications.
|
Pay Item No. |
Name |
Unit of Measurement |
| 10.13(1) | Box Culvert – Type A |
linear metre |
| 10.13(2) | Box Culvert – Type B |
linear metre |
| 10.13(3) | Box Culvert – Type C |
linear metre |
| 10.13(4) | Box Culvert – Type D |
linear metre |
| 10.13(5) | Box Culvert – Type E |
linear metre |
| 10.13(6) | Box Culvert – Type F |
linear metre |
| 10.13(7) | Box Culvert – Type G |
linear metre |
S10.14 Technical Box Culvert
S10.14 (1) Description
This work shall consist of the construction of longitudinal and cross technical box culverts (technical tunnels) and associated manholes and accessories in accordance with these Specifications, the specifications for other work items involved, all in conformity with the lanes, grades and dimensions instructed by the Engineer.
S10.14 (2) Consultation and Drawings
Location of the culverts and associated manholes as shown on the Drawings, are not to be taken as final. The final arrangement of the culverts will be instructed by the Engineer in such a way to facilitate the future development of water, power and communication lines.
S10.14 (3) Sequence of Works
In area where significant settlement is expected below new embankments, the culvert works should be delayed until the settlement is substantially completed. Soft soil treatment shall be provided as necessary and the Contractor shall consider the delay when preparing his schedule of site works The Contractor shall provide adequate protection of the works and traffic, including securing detours for passing vehicles and pedestrians all in accordance with the relevant clauses of these Specifications.
S10.14 (4) Materials
All materials shall comply with the relevant requirements of these Specifications and details shall be as shown on the Drawings. Where the drawings show the use of pre-cast units these shall be factory manufactured and before the Contractor places any orders for the supply of the culverts, the factory must be inspected and approved in writing by the Engineer.
S10.14 (5) Construction
(a) Excavation
All excavation shall be carried out so as to minimize damage to existing surfaces and the works shall be carried out in accordance with relevant Clause of Section 5 – Structure Excavation.
(b) Basing and Bedding of Pre-cast Units
Prior to laying the pre-cast units, the foundation shall be prepared to the thickness as shown on the Drawings. The crushed stone foundation shall be finished with a thin sand layer vibrated into the crushed stone to prepare the surface for the laying of the pre-cast units.
A thin grout of bedding mortar shall be loosely spread on the foundation immediately before placing of the pre-cast units. Where previously placed mortar begins to set or is compacted unintentionally before placing of the units, that portion shall be removed and replaced.
(c) Laying of Pre-cast Units
All pre-cast units shall be laid carefully to the true line and level as directed by the Engineer. Laid units shall be jointed by welding the exposed reinforcement and the joints shall be sealed with concrete Class C, to form a watertight joint. The faces at the joint area shall be wiped and finished smooth and the external face of the joint shall then be treated / sealed as shown on the Drawings.
(d) In-situ Concrete Works
The works of in-situ concrete for longitudinal and cross culverts shall be carried out in accordance with Clause S10.01 and S10.02
(e) Installation of Hangers
Unless other details are shown on the drawings, the work on the Type I Technical Culverts shall include the provision of hangers fixed to the walls of the culvert to facilitate the installation of the utilities. These hangers shall be steel and galvanized after prefabrication. They shall be fixed to the wall by galvanized anchor bolts installed in drilled holes and each hanger shall be capable of carrying a load 400kg. The number of hangers will be approximately 4 per 1 metre length of culvert but the Engineer will instruct the height and spacing of the hangers after discussion with the utility companies.
(f) Maintenance Accessories
Withdrawn
(g) Backfilling and Reinstatement
Back-filling shall not commence until in the opinion of the Engineer, the concrete has achieved sufficient strength. Backfilling and reinstatement shall be carried out in accordance with the requirements of Clause S6.05 (3) c) .05. The material used for backfill around culverts for a minimum distance of 50 cm shall be sand in place of excavated material.
S10.14 (6) Method of Measurement
The quantity of technical culverts to be paid for shall be the number of linear metres measured along the centreline of the culverts, between the intersection points of the culvert lines installed in accordance with these Specifications and the Engineer’s instructions. Where the culvert system terminates at a manhole, the measurement will be taken from the outside wall of the manhole opposite the remainder of the culvert.
Type I technical box culvert is 2m x 2m and these will generally be installed transverse to the main road centre line. Type II technical box culvert is 1m x 1m and these will generally be installed in sidewalks parallel to the main road centre line.
S10.14 (7) Basis of Payment
The price and payment will be full compensation for installing each type of culvert as shown on the Drawings and for all labour, tools, equipment and incidentals necessary to complete the work as described in this Specification. There will be no separate measurement or payment for the manholes as these will be considered to be included in the work of the culverts.
Pay Item No. Name Unit of Measurement
10.14 (1) Technical Box Culverts (Type I) linear metre
10.14 (2) Technical Box Culverts (Type II) linear metre
S10.15 Balanced Cantilever Construction
In addition to the foregoing clauses, the work on balanced cantilever construction shall be conducted in accordance with the following:
S10.15 (1) General
Where the superstructure of the Bridge is to be constructed by the balanced cantilever construction method using formwork traveller, alternate construction sequences to that shown on the drawings shall require a redesign of the structure.
The Contractor shall submit construction sequence of the superstructure together with backup calculations to the Engineer for review and approval. Before submission, the Contractor shall carefully study construction circumstances such as anticipated climate conditions at site (humidity, temperature and rain fall) and structural influences of secondary stresses due to dead load of girder, prestressing forces, creep and shrinkage of concrete, and temperature.
S10.15 (2) Forming System
The following computations and working drawing shall be submitted for the Engineer’s review and approval.
- (1) Complete details and computations for the form and form support system including maximum loading and stresses that may occur in the concrete segments due to formwork equipment and concrete placement. Design of form support system shall include adequate allowance for impact loading that may occur during concrete placement and advancement of forming system.
- (2) Computation of deflection of the forming system during concrete placement.
- (3) Details for temporary supports and tie-down as needed to stabilize the cantilever during construction.
- (4) Detailed sequences of concrete placement, stressing and advancing the form support system and adjusting the calculated deflection.
- (5) Detailed procedure for fixing the cantilever ends against changes in position or rotation of one cantilever relative to the other during and following placement of concrete for the closure between the cantilevers.
- (6) Checking concrete stress in the box girder sections, and calculation of cable elongation during stressing.
- (7) Other additional calculation and drawing as required by the Engineer.
S10.15 (3) Superstructure Construction
This work shall consist of, but not limited to, casting concrete segments, stressing and setting the superstructure in accordance with approved procedures.
- (1) The Contractor shall submit complete details and descriptions of the methods and equipment to the Engineer for approval before the commencement of superstructure construction.
- (2) The construction method shall include casting of the segments, methods of the tie-down of superstructures during cantilever erection, method of application of all temporary forces to be used for adjusting horizontal and vertical alignment. This shall also include control methods to ensure the accuracy of alignment of the completed superstructure.
- (3) Work equipment shall include all machinery, devices, labour and material which are to be used for erection but will not become a permanent part of the completed superstructure. Equipment must not be operated from or placed upon any part of erected superstructure at any stage of construction other than which specifically meets the requirements of total working load per segment as approved by the Engineer. This includes the post-tensioning, grouting equipment and any other equipment whatsoever, and men and materials of any special kind required for the work.
- (4) Construction load shall be checked by the Contractor at every stage of construction and be reported to the Engineer for approval.
- (5) Construction joints will be limited to the locations shown on the drawing or as approved in advance by the Engineer. All construction joints shall be thoroughly cleaned of laitance and foreign material prior to placing concrete for the next segment.
- (6) For placement of closure concrete between cantilevers, the cantilevers shall be fixed to prevent rotation or movement in any direction of one cantilever relative to the other. The system for locking the cantilevers and forming for the closure and the procedure for placing the concrete for the closure shall be such that the concrete after the initial set shall not be subject to any tensile forces that could cause cracking.
- (7) The Contractor shall submit a construction schedule showing chronological order of every phase and stage of erection and construction of the superstructure.
- (8) The Contractor shall prepare a table of elevation and alignments required at each stage of erection, as per drawing, at the check points listed below, or an alternate at his option, and submit the same to the Engineer.
- a. One of the lowest corners at the top surface of any bearing device to be used as datum during erection and to establish a reference point with the actual elevation and alignment required of the permanently positioned superstructure.
- b. All four corners and centreline (at segment faces) of top slab of pier segments to establish grade and crown.
- c. Two points on the longitudinal centreline of each pier segments, one on each edge, to establish alignment.
- d. One point on the longitudinal centre line and, at least, one corner of each segment along every joint between segments to establish elevation and alignment at every stage of erection.
- (9) The temporary bearing pads, if applicable, at the pier shall be very carefully placed. The top surface of this pad shall have the correct elevations, alignments and slopes as required by the drawing. Shims may be used underneath the pads to accomplish accuracy. The contractors shall also device and provide measures to hold temporary bearing pads in position while the pier segment is being cast.
- (10) The contractor shall check the elevation and alignment of the structure at every stage of construction in accordance with the approved geometry control plan and shall maintain a record of all these checks and of all adjustments and corrections made.
The cost of complying with this Clause will not be paid for directly, but will be considered to be included in the Bid prices for pay items under the Contract.
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