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Saturday, May 5, 2012


11.4   Material

11.4.1 General

All materials used in this section shall be supplied from the sources satisfying the requirements given, here inf or elesswhere in this specifications and approved by the Engineer,

11.4.2 Sub- Base Course Aggregate

Provide a  mixture  of  sand-gravel  subbase  of  thickness  specified  on  the Drawings complying with AASHTO T-27 and with modified CBE value of r.ot less than 20 when tested at 95% density of maximum dry density at optimum moisture ontent. The materials  should be free from lumps or balls of clay , vegetable matter , objectionable coatings, or other foreign material-

The souroe of the materials to be Bead for. producing the sub-base aggregate shall be selected Tifell in advance of the tine they will be required in the work. The portion of  material  passing 0.4 ram screen shall have plasticity index ASTM DH24 of not more than 6 and liguid linitl  ASTM DH23, of not more than
25 or as reguired by AASHTO T89-68 . The materials shall be obtanined from one source which satisfying the requirements
and approved by the Engineer.

Grading reguirements shall comply with the sieve anaylsis given by AASHTO T-27 Type B, This gmdation represent the limit which shall determine suitablity of aggregate and sources of supply. The final gradations decided on shall be well graded from coarse to fine ( as designated in the AASHT- T-27) and shall not very from the low limit on one sieve to  theKigh limit on the adajacent sieves, or vice versa.

The materials  shall  be  compacted  to  a  density  of  not  less  then  95%  of maximum dry density at opimum moisture as determined in accocdance with AASHTO T180 method " D".  Approved materials for subbase shall be stock piled in the manner and at the locations designated by the Engineer, Materials obtained from different sources , Shall be stockpiled separately,

11.4.2 Concrete Materials

a. Ordinary Protland Cement

The  cement  used  shall  conform  to  ASTM  C150,  AASHTO  M85-74,  or complying  in  all  respect  with  B.S.12:1971  .  The  contractor  shall  provide appropriate dry , weather - proof sheds of sufficient capacity to store cement. The cement shall be used as soon as possible after delivery. Any cement that

has been stored for a period exceesing 3 months shall not be used until it has been tested for suitability.

Any deteriorated cement shall not be used for concrete

b. Fine Aggregate Fine aggregate shall be moderately sharp and free from soft particles, clay, shell, loam or any other deleterious materials. The soluble sulphate ( S03) centent shall not exceed 0.5% when tested in accordance with B.S 1377 test No. 10. The amount of  sulphate ( S03) in the concrete rcass shall not exceed 4.5 % of weight of

Cement in the total concrete mass .

The sand shall comply with the following grading when tested in accordance with AASHTO T27- 74 or ASTM 33.

Sieve Size mm


% Passing by Weight


3/8 in



No. 4

95 - 100


No. 16



No. 50



No, 100

2- 10


No. 200

0 -30

The grading from any ace source shall be reasonably uniform and not subject  to  the  extreme  percentages  of  grading  specified  above  .  The contractor  shall  execute   a  quality  test  on  fine  aggregate  and  each aggregate source , and the results shall  be submitted to the Ihgineer for approval.

c. Coarse Aggregate

Coarse aggregate shall consist of either natural gravel, or curshed stone or crushed  gravel. All coarse aggregate shall je produced f stockpiled and batcliod as a  signal-sized materials complying with the grading limits of ASTM C33 or AASHTO ( T27 -74) . For convenience the ASTM  C33 are produced as follows:

Sieve Size mm


% Passing Ity weight


2 in



1 1 ;2  in

90 -100


3 ;4  in

35 -70


3 ;8  in

10 -30



The aggregate shall be composed of sound, tough, durable particles free from clay
balls, organic  matter,  and  other  deleterious  materials  ,  The  aggregate  shall  not contain  more  than  8%  by  weight  of  flat  or  elongated  pieces.  Other  physical reguirements of the coarse aggregate shall be within the linits given below:

Physical Property

Maximum Permissible    Limits (% by weight)


Soluble sulphate conteat Sr3

( B.S 1377,  Test Ho.  10)



Sodium sulphate soundness
( AASIITO T104 -74



Wear L.A. Abrasion (AASHTO T96-74)



Friable Particles



Coal and Lignite  (AA.SHTO T133-70)



Clay Lwrvps   (AASHTO    T112-74)



Ifeterial   Passing1    the    0.075    mm        ( AASHTO T11-74)



KLengation Index ( BS 012)



Flalciness Jhdez ( BS 012)


The controctor shall execute a quality test on coarse aggregate and each aggregate source and the results shall be submitted to the Engineer for approval .

d.        Admixture

1.                      Air     Hitraining     Adnixtures     for     concrete     shall     be      in accordance with MSHTO M154.

2.  Chemical  Admixture  for  water  rodnction  f  set  retardation  and  set acceleration or their combinations shall be in accordance with AASHTO M194.

e.    Mixing water

Mixng water shall be clean and free from oil, acids, alkalis , salts, organic material or subetance which may deleterious to concrete or reinforcement. The contractor shall store on the site an  adequate supply of fresh water to meet all n.eeds. The water shall be tested as prescribed in MSHTO T26-72.

f.     Reinforcement

Concrete reinforcement shall be of wire mesh as shown on the drawings. The wire mesh shall be of welded plain cold drawn steel wire fabric mats complying with ASTM A185  AASHTO M55 - 73 , or B.S 4483 ( 1969). The mesh shall be furnished in flat sheets,  not  rolls,  unleas  otherwise  acceptable  to  the  Engineer.  Minimum  yield strength 40Kgs/mm2  .

The mesh shall be rectangular with clase spacing between langitudiioal  bars and wider spacing1 between transverse.

g. Polythene sheeting

Polythene sheeting  for placing immediately below concrete slabs shall be 0.065 mm thick made from polythene or other approved hydrocarbon thermoplastic resin.

11.4.4    Joint Filler

1.     Provide resilient and nan-estruding type premolded cork units or sponge Rubber joint filler or any other equivalent material approved by the Engineer.

2.       Provude sizes,  and shapes of units as recommended by the manufacturer for joint size and condition shown.

Where joint movement is a factor in the determination of size,       consult with the

Sigineer to determine ruature and magnitude of anticipated joint movements for the temperature and condition of project at time of installation.

3.       Specified hardness and conpressibilities are intended to establish requirements for  normal or average conditions of installation and use . Where a range of hardness          or compressibility                              is    available    for    a    product,    comply    with manufacturer's recommendations for specific condition of use.

4. The joint material shall not deteriorate under any weather conditions and is to be of such  a  character  as  not  be  permanently  deformed  or  broken  by  moderate twisting) bend ing or other ordinary handling.

5. Strips of the joint filler which do not conform to the specified dimensions within the tolerance 0+2ram for thickness and + ;-12 mm for depth are to be rejected . All damaged strips are to be rejected.

6.    Joint filler material shall be compatible with the substrate, sealants, and other materials in the joint system.

11.4.5 Joint sealer

1. The sealing material shall be impermeable, withstand all weather conditions and capable of  adhering firmly to concrete without cracking, spalling or disintegr - ating and will not reguire an impracticticable condition of dryness or cleanliness of concrete slabs. The prefarable materials used as sealing compound shall be hot- poured rubber bitumen compounds material or  synthetic  rubber content or any other satisfactory materials approved by the Engineer.

2.  The sealant material shall be compatible with joint surfaces, joint fillers and other materials in the joint system.

11.4.6 Joint Dowel Bars and Tie 3ars

Dowel 3ars shall be of mild plain steel bars complying with the requirements of ASTM A615 or BS 4449 ( 1969) and as shown on the drawings and table (l). Cut bars to true length with ends  sguare and free of burrs. Dowel bars for contraction and expansion joints shall be of dimensions and spacing shown in Figs,(2, 3) and table (3).

Tie bars for the longitudinal joints are 12mm diameter mold steel 1m long centrally located over  the joint centre line at mid - depth of the slab and speced at 600mm centres.

As an alternative to mild steel, 10mm diameter high yield steel tie bars 750 mm long may bo used

11.4.7   Metal Expansion CapsFurnish the end of the coated half of each dowel bar in ercpansion joints with a steel or cardboard cap about 100mm. long. The aid of the cap shall be filled with cotton waste or similar compressible material to allow for bar movement of not less than 25am and  as shown on the drawing unless otherwise indicated.

11.5 Sampling and Testing

All materials shall be approved by the Engineer prior to use in the work. Additional samples will be taken and tested by the Engineer during the progress of the work to check on the gualily of the material being supplied and/or placed by the contractor.

The contractor should set up his otm testing facilities or arrange the same from the private  laboratory to assure that his materials and workmanship comply with the spicifications,

11.6 Concrete Mix and Design

11.6.1    Composition

a.       All concrete shall proportioned by weighing and shall conform to the following strength and mix reguirements.

1.        compressive    stregth,      250 Kg/cm2, minimum at 23 days when tested in accerdance with AASHTO T-22

2.    Minimum cement content 3uO Kg/m.

3. Maximum slump  ( 50mm) whea tested in accordance with

4. Air content 4-7% when tested in accerdance with AASHTO T 196

b.  At least 35 days prior to the start of paving operations and after approval of all materials to be  use in concretes the contractor shall submit for approval the mix design he intends to use based on proportioned weights of cement , air enteraiment agent, saturatod surface dry aggregate , and water, This mix design will be tested by the  Engineer  and  approval  will  not be  granted  unless  the  average  28  days compressiv.e strength the exceeds the minimum stregfch regvireraents by at least 15
The making cuiring,  and testing of the specimens for the compresive strength of the concrete shall be in accordance with AASHTO T 23-73.

c. The reguired consistancy of the concrete mixture shall

be such that the mixture will be choesive, uniform and plastic permitting proper handhing and finishing when deposited, it shall not flow, but shall remain in a conical pile and shall be minimum segregation during the process of hardling and finishing.

11.6 .2 Batching and Mixing

Concrete shall Either be batched and mixed at a central batching and mixing plant, or batched at a central batching plant while mixing can be either by field mixers adjacent to the forms for slabs, or mixed in a truck mixer.

11.7 Forms

Side forms shall be made of metal or any other approved material. They shall be of opproved construction and provided with adequate devices for secure setting so that i/hcn in place^ they shall withstand the impact and vibration of the compacting and finishing wruipment with settlement not exceeding 1.5mm  3m. Form sections shall be tightly joined by a locked joint free from play in any direction.

Bent, twisted or battered forns arc to be removed from the site. Repaired, forms arc

not to be used unless approved by the Engineer. Wooden forms may by used only for curves having  a  radius of less than 50m. They shall be made of two 2.5cm well seasoned surfaced planks fas tented together and. shall be attached securely to a wooden base 20cm in width . All wooden forns shall be braced at least every 60cm with steel pins of the size and length approved by the Engineer.

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