### concrete mix design calculation - m20, m25, m30

Procedure for Concrete Mix Design of M25 Concrete Step 1 — Determination Of Target Strength Himsworth constant for 5% risk factor is 1.65. In this case standard deviation is taken from IS:456 against M 20 is 4.0. f target = f ck + 1.65 x S = 25 + 1.65 x 4.0 = 31.6 N/mm 2. Where, S = standard deviation in N/mm 2 = 4 (as per table -1 of IS 10262- 2009)