RCC SLAB CASTING – WORK PROCEDURE
Materials and Machinery used
- Batching plant.
- Transit mixer
- Concrete pump
- Chute and CI Pipes
Scope of the work
- Marking the slab
- Placing the reinforcement
- Form work for slab
- Placing the concrete
It shall be as per BBS prepared according to approved drawing. The R/F shifting and binding shall be started as soon as shuttering is completed. R/F binding shall continue as formwork and shuttering work is progresses.
The construction joint shall be pre decided and fixed prior to start of the concreting. It is planned to have two construction joints for main building as decided. In case of major break down of the Batching plant, the additional Construction joint may be left. The location of the construction joint shall be at the one-third span. Construction joint shall be straight and have profile of ‘L’shape so that successive layer of concrete shall be perfectly bonded with previous laid layer.
Preparation of construction joint shall include roughening, removing all laitance adhering to the joint and application of thick slurry before start of the new concrete.
Production and placement of concrete.
Stock of material shall be sufficient to start the concrete. It shall be ensured by stores/purchase dept that concreting is not stopped on account of materials.
All plant and machinery are checked and made in working conditions.
Concrete of grade M-25 shall be produced from our batching plant and directly pumped to the location of concrete placement through the pipeline. The pouring sequence shall be from grid A towards construction joint. Since the grade of concrete for column is M-40 and surrounding concrete is M-25, sufficient offset around column shall be casted with M-40.The offset dimensions shall be provided by PMC.
Proper walkways/platforms shall be arranged so that the supports of the pipeline and manpower are not directly stand on reinforcement.
Sufficient carpenters along with supervisor shall inspect the behavior of supports below the slab during the casting. Extra Props shall be stocked below slab to provide additional supports in case of any failure of supports.
The curing shall be started immediately after thumb set of the concrete laid. Hessian clothe /Plastic shall be covered over the set concrete to reduce moisture evaporation from the concrete during hardening and thus to minimize shrinkage crazy cracks. These cracks are inheriting property of the concrete specially appears during casting of flat surfaces.
Final curing shall be done by ponding and stacking water for minimum period of 7 days.