Design mix is to attained the specific strength of concrete
in 28 days .M25 means whos Cube test results are 25N/SQMM
after 28 days.Proportion in Different grade of mix is
decided by Trial mix in Lab,For which there is different
We cann't fix the proportion like Nominal Mixes...because in
above Concrete mixes, Locally available Material are
influence the Strength...and in M-40 we could not fix
because these mix design can't prepare without Plasticizers...