Talbot-Richart Method:

This method is based on the experimental investigations, in which the compressive strength of concrete depends upon Cement Space Ratio (CSR) given by:

 CSR =C/(C + v)

 where, C = Solid volume of cement, and

V = Volume of water plus voids per unit volume of freshly made concrete.

This method is not popular, as it requires more laboratory work. It also does not take into account the water-cement ratio law as the basis of strength. This method involves complicated calculation work and trial mixes to achieve a workable mix.