What is right M20 or M25 concrete for structure for G + 1 ?

[Visualizer]

Hi,

I am planning basement GF and FF and want to give full contract. In some of quotes the specification says M20 Concrete for pillars and slab. Can some one please guide what is standard concrete used in residential construction. Is it M20 or M25 ?

Regards

[Armchair_general]

M20 is the standard. But I have used M25 because I want structural integrity, longer curing time and also architect recommended that M25 ensures that building will not age and lose it looks over a period of time. I am using riversand, cement 43 grade. Bit expensive but worth it.

[Visualizer]

Thanks for reply , however just curious how longer curing time is related to compressive strength of concrete and why would you prefer longer curing time ?

[Armchair_general]

Longer curing time exposes the structure to the environment and temperature variables. The structure will settle down and will reduce the number of cracks. I was advised every structure has to see all three seasons before starting with the plastering.