Concrete basic properties

English Units
E_c = {w_c}^{1.5}\; 33\; \sqrt{({f_c}^')}

where

E_c = modulus of elasticity of concrete (psi)

w_c = unit weight of concrete (lb/ft3)

{f_c}^' = specified compressive strength of concrete (psi)

Note: the formula is applicable for w_c between 90 and 155 lb/ft3

For normal weight concrete, E_c is permitted to be taken as 57,000 \sqrt{w_c}.