I can not use Fly Ash bricks in raft and beam column because of strength issues. Can I replace cement with fly ash in Grade Slab and fulfill criteria 19.1.1? Also, what is the definition of structural work or structural concrete? Is there any volume of the structural concrete required that we need to replace with fly ash?
Yes, you can replace cement with fly ash in Grade Slab and fulfill the requirements of appraisal 19.1.1. PCC used for Grade slab is also considered as a structural member for assessment in GRIHA appraisal 19.1.1. Nevertheless the project may fulfill appraisal 19.1.1 only if minimum 15% cement by weight is replaced with fly ash for all structural concrete used. A copy of IS code may be attached to prove that required strength may not be achieved using PPC.
Structural work consists of columns, beams, raft, walling, arches, vaults, cantilevers, domes, shell and core, rafters, frame etc. The concrete used to cast or construct these are categorized as structural concrete.
As per GRIHA requirement, a minimum 15%/ 25% of Ordinary Portland cement should be replaced with fly ash* by weight of cement used in structural concrete.