The following empirical relationship are available which are as follows:

(1) 𝐸𝑐=1.25𝐸𝑑−19

(2) The British testing standard BS8100 Part 2: 𝐸𝑐=1.25𝐸𝑑−19 (GPa).

(3) Considering the effect of concrete density the relation is 𝐸𝑐=446.09 𝐸𝑑1.4 𝜌𝑐 (GPa)

where 𝜌𝑐 is the density of the hardened concrete in a unit of kg/m3.

thank you so much Dr. Chitaranjan Pany for these information

best regards