Quality Assurance Handbook for Rural Roads Volume-I - pmgsy

3. Section-1500
5 Mark location and type of the joints on either side of the surface of the sub-base, with red paint.
(i) Contraction joints shall be mechanically sawn joints spaced 2.5 m to 3.75 m. Length of panel in the
direction of traffic shall not be less than the width of the pavement. Joints shall be cut when the
pavement is neither too soft nor too hard and is able to bear the weight of the machine and crew.
Normally it may vary from 8 to 12 hours depending on weather conditions.
(ii) Construction joints shall be butt joints and placed after a day’s work is over or when work is
suspended for more than 30 minutes.
(iii) Expansion joints shall be provided near bridges and slab culverts and consist of a bitumen
impregnated joint/ premoulded synthetic joint filler board, about 20 mm thick, and dowel bars.
(iv) Longitudinal joints shall be provided for a two-lane road and shall be saw-cut.
6 All side forms shall be of mild steel channels or fabricated plates with adjustable jacks at the back
and of depth equal to the thickness of pavement. Plant, equipment and tools required for
preparation and laying of pavement concrete are listed in Clause 1501.11.2 of Specifications for
Rural Roads.
7 Pavement concrete shall be produced near the site, using approved concrete mixers of at least 0.2
cum capacity. Readymade concrete conforming to the specified properties of strength and
workability may also be used.
8 Check the slump of concrete. It should be in the range of 30 mm ±10 mm
9 Concrete shall be placed between the side forms and shall be levelled with rakes and shovels. In
concrete panels having acute angles, a bar mat of 10 mm dia ribbed steel bars at 150 mm center to
center in both directions shall be provided at 50 mm below the top of slab, in the entire panel.
10 Around man-holes or other openings in pavement, place 12 mm thick pre-moulded board as per
IS:1838 and bar mats before concreting.
11 Compact concrete by a vibrating screed supplemented by two internal vibrators.
12 As soon as practicable after compaction of concrete, smoothen the surface with a longitudinal
float operated from the work bridge. Just before the concrete becomes non-plastic, it shall be
textured with a long handled steel or fibre brush.
13 After completion of texturing , before the concrete has taken its initial set, the edges of the slab
shall be carefully finished so as to leave the pavement edges smooth and true to line.
14 After completion of the finalizing operations, the surface of the pavement shall be covered with
wet Hessian cloth, burlap or jute mats. They shall be maintained fully wetted and in position for
24 hours.
Upon the removal of the wet covering out the end of 24 hours, the slab shall be thoroughly wetted
and then cured by ponding or sprinklers.
The slab shall be covered with sufficient sandy soil so as to produce a blanket of earth not less
than 40 mm thick after wetting. The earth covering shall be thoroughly wetted while it is being
placed in the surface and against the sides of the slab and kept thoroughly saturated with water
for 14 days. The sand shall not be removed and shall thereafter remain in place till 28 days from
date of casting so that the concrete has attained the required strength.
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