Vicky - Questions

(FYI : PPC is environment friendly as it consists fly ash in some specific percentages by parts, which is a waste product of burnt coal, usually collected from thermal power plants)

OPC (m53) attains strength in a shorter time, while PPC (m43) takes longer.
OPC therefore dries more quickly, but produces more heat during chemical reaction during which it gains strength, as compared to PPC
Faster is the drying process, more is the risk of cracking of cement, and therefore it need more care and more amount of water for curing in a lesser time.
PPC on the other hand can attain strength equal to OPC, but takes a longer time.

For a building slab, PPC is more widely used since it requires less care.
The strength depends on design mix (the water cement and aggregate ratio) more than type of cement.

so essentially, If you need construction to take place faster and have means for good curing, you may use OPC.
But if you need better quality and strength in less effort, use PPC.

It still depends on the structure’s design requirements and a structural designer’s advice is to be followed.

Hope this helps, but do consult an engineer before using any type of cement.
Building construction is a responsible job and needs to be done safely and one must adhere to engineer’s specifications.