The grade of concrete corresponding to nominal mix proportions of 1:3:6 is
- AM-35
- BM-25
- CM-15
- DM-10Correct
Solution
Concept
Nominal mix proportions of concrete grades
Formula
NONE
Step-by-step solution
1. Nominal concrete mixes specify fixed proportions of cement, fine aggregate, and coarse aggregate by volume. 2. A ratio of 1:3:6 corresponds to 1 part cement, 3 parts fine aggregate, and 6 parts coarse aggregate. 3. As per IS 456, the nominal mix proportion 1:3:6 corresponds to M-10 grade concrete. Answer: D
Explanation
Nominal mix proportions specify the volumetric ratio of cement to fine aggregate to coarse aggregate in a concrete mix. A ratio of 1:3:6 corresponds specifically to M-10 grade concrete, which has a characteristic compressive strength of 10 N/mm² at 28 days. Higher grades use richer mixes, such as 1:2:4 for M-15 and 1:1:2 for M-25.
Why the other options are wrong
A) M-35 is a design mix grade, not a standard 1:3:6 nominal mix. B) M-25 corresponds to a nominal mix proportion of 1:1:2. C) M-15 corresponds to a nominal mix proportion of 1:2:4.
Shortcut
Nominal concrete mix ratios: M10 is 1:3:6, M15 is 1:2:4, M20 is 1:1.5:3, and M25 is 1:1:2.
Common mistake
Confusing the nominal mix ratio of M-10 (1:3:6) with M-15 (1:2:4) or M-20 (1:1.5:3).
Correct answer: D) M-10