Age strength of concrete

Strength of concrete on perticular required day can be find out by following formula as per SP 24 :-

t/(a+bxt) x fck

Where,

t, is the age in days
a, is value = 4.7
b, is value = 0.833
fck, is compressive strength of the concrete

Example:

To find compressive strength of concrete on 3rd day , fck is 35 N/mm2

Implementing above formula

t/(a+bxt) x fck

3/(4.7+0.833x3) x 35

= 14.59 N/mm2

Which is 15/35x100= 41.67% of fck

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