In concrete mix design, what is the nominal mix ratio for M20 grade concrete as per standard engineering specifications?

Explanation

Nominal mix ratios for concrete grades are M5 (1:5:10), M7.5 (1:4:8), M10 (1:3:6), M15 (1:2:4), M20 (1:1.5:3), and M25 (1:1:2). Thus, M20 has a nominal proportion of 1 part cement, 1.5 parts fine aggregate, and 3 parts coarse aggregate.