Plain Cement Concrete of M15 grade (thickness of 100mm) are mandatorily placed on a ground/soil strata, to give a firm,clean base for placing reinforcement cage,as we start building foundation of a RCC structure.
It is also help in following ways:
1.Required cover to bottom reinforcement is ensured ,as cover blocks rest on a firm PCC .
2.The effective depth of RCC members is achieved as the formworks can be easily,uniformly and sturdily fixed ,resulting in better dimension accuracy of foundation RCC member.
3.Reinforcement steel placed on a PCC, are never in touch with ground soil ,which may be chemically active may lead steel corrossion in immediate future (when in contact with ground soil )
4.Ease placement of steel cage and increase productivity.
5. Concrete don’t bond with ground soil (clay),PCC acts a barrier to soil and bond well to overlayed structural grade concrete.
Note : Ensure good curing of PCC too.