METHOD STATEMENT OF CEMENT CONCRETE PAVEMENT

 

Cement concrete pavement 

     1.0      General

1.1    This work consists unreinforced, dowel jointed, plain cement concrete pavement.

1.2   The Thickness of pavement slab, grade of concrete and joint details shall be as stipulated in the approved drawings.

         2.0         Materials

                         Cement:

Ordinary port land cement of 33 grade (IS: 269), 43 grade (IS: 8112) and 53 grade (IS: 12269) may be used but the preferences shall be to use at least the 43 grade or higher.

2.1.1                    Aggregates:          

2.1.2                    Coarse Aggregates shall be of hard and durable crushed stone complying with (IS: 383) but with a loss angles abrasion Test result not more than 35 percent and water absorption shall not be more than 2 percent. The maximum size shall not exceed 25mm. Soundness test result in accordance with (IS: 2386) shall not be more than 12/18 percent if sodium sulphate /magnesium sulphate is used.

2.1.3     Fine aggregate shall be of natural sand conforming to (IS: 383). Material passing IS sieve No. 75 micron shall not be more than 3 percent.

2.1.4                    Water

Clean water free from injurious oils, salt& acid should meet requirements stipulated in IS: 456.

         3.0     Proportioning of concrete

3.1       The Mix design shall be based on laboratory trial mixes as per IS: 10262 and               IS:SP: 23 and strength testing shall be as per clause 903.5.2 of MOST (Ministery            of Road Transport & Highways)

3.2        The cement content shall not be less than 350kg per cum of concrete and not  

            Exceed 425 kg per cum of concrete.

3.3        The maximum free water cement ratio shall be 0.45

3.4        The materials and mix proportions remain substantially unaltered during the

           Day’s production.

3.5       A slump value of 30+15mm is reasonable workability requirement for paving  

           Work and these tests may be carried out on alternate truckloads.

4.0     Joints in concrete pavements

             Joints may be classified as transverse and longitudinal joints. Transverse joints are further classified as contraction, expansion and construction joints depending upon their functional requirements.

          4.1     Longitudinal Joints:

4.1.1    These are joints between adjoining lanes of pavement to control cracking

          in longitudinal direction.

4.1.2 Tie bar of 12mm dia & 650 mm in length shall be provided at 550 mm c/c

          Spacing.

                   4.1.3   These joints shall be saw cut as per details in the drawings.

        4.2    contraction Joints:

4.2.1   These are straight transverse joints at specified intervals (4 to 5 mts)                  to Control cracking due to shrinkage and contraction as the concrete hardness.

4.1.2  Contraction joints shall consist of a mechanical sawn joint groove, 3 to 5mm wide and ¼, d/4 depth of the slab + 5mm or as stipulated in the drawings.

4.1.3  Load transfer dowels shall be of mild steel bars of specified size (depending on thickness of pavement) and of 500 mm in length spaced at 320 mm intervals at mid –depth of the pavement slab and should be parallel to the finished surface of the slab.

4.1.4 The dowel bar shall be supported on cradles in pre-fabricated joint assemblies positioned prior to the construction of the slabs or mechanically inserted with vibration into the plastic concrete. Cradles shall not extend across the line of joint.

 

                4.3       Expansion Joint:

4.3.1        Relief for compression stress in hot weather is provided at bridges and at intersections in the form of expansion joint.

4.3.2        Non-Extruding compressible filler board of entire thickness over that polysulphide joint filling compound 20 mm thick and 20 mm less in depth than the slab shall be provided to the full width between the side forms. Holes shall be accurately punched to give a sliding fit on the dowel bars.

4.3.3        Joint sealing shall be of  cold polysulphide type applied in accordance with BS 5212-1990.

4.4      Surface Texture

4.41          Texturing/Tinning shall be done with specified designed for the purpose 

Providing grooves at an uniform spacing (c/c) of 18mm to 21 mm,depth (3mm to 4mm) and width (3mm),parallel to the centre line of roadway extending over the entire roadway width but within 75 mm of pavement edge & omitting within +/- 20mm of the sawed longitudinal joints. 

 

            4.5       Equipment

      (i)    Batching Plant with automatic weighing devices to proportion aggregates and bulk cement.

(ii)   Pan type reversible type mixers equipped with timing device

(iii)   Centralized control cabin

(iv)    Wheel loaders

(v)     Tipper trucks

a) Spread b) Consolidate and c) Finish and cure the freshly placed concrete in one complete pass of the machine. The paver shall be equipped with electronic control.

5.0     Trial length construction

5.1    Trials shall be carried out using the same paving width and slab thickness as           used in the permanent works.

5.2     The materials, plant and equipment shall be demonstrated by constructing a            trial  length of slab at least 60mts but not more than 300mts long.

5.3    The trial length construction shall be in two parts over a period comprising              at least part of two working days minimum of 30mts each day.

5.4    Transverse joints and longitudinal joints of each type shall be constructed and       assessed in the trial length

5.5 The surface regularity shall satisfy 902.4 of MORTH (Ministery of Road Transport & Highways) and the                maximum  allowable difference checked with a 3mt straight – edge shall be 3mm.

5.6  Density shall be assessed from at least 3 cores drilled from each part of the     trial length.

6.0          PROCEDURES

      6.1    Concrete from the batching and mixing plant shall be transported by means of       .            Sufficient trucks/tippers without segregation and loss of slurry.

   6.2    The total time taken from addition of water to the mix, until the completion of the        surface finishing and texturing shall not exceed 120 minutes when                              concrete temperature is less than 25⁰c and 90 minutes if it is between 25⁰c to              30⁰c and work may not be continued if the temperature of concrete is more                   than 30⁰c.

   6.3       If considered necessary the paving machines shall be provided with covers to                     protect the surface of the slab under construction from direct sunlight and rain or                  hot wind

      6.4       The concrete shall be placed with an approved fixed formwork construction in

                   Restricted areas in small lengths may be hand-guided method.

6.5      After final regulation of the slab the surface of concrete shall be brush – textured      in a direction at right angles to the longitudinal axis of the carriageway. The              brush  shall be not less than 450mm wide and made of 32 gauge tape wires 100        mm long spaced at 10mm centre and the brush shall have two rows of tufts                20mm  apart. The texture depth shall not be greater than 1.25mm.

     6.6    Immediately after surface texturing, the surface and sides of the slab be cured                       by application of curing compound using mechanical sprayers. After three hours                  the Pavement shall be covered by moist hessian kept damp for a minimum period of              14 days. No vehicular traffic shall be allowed within a period of 28 days of                            pavement Construction and until the joints are permanently sealed.

   7.0  TESTS REQUIRED:

           Quality control test as per 903.5.1 of MORTH  (Ministery of Road Transport &                     Highways) shall be carried out.