Strength of Concrete MCQ with answer and solution

Concept

Standard concrete cube dimensions for compressive strength testing as per IS codes.

Step-by-step solution

1. Identify the standard code provisions for testing concrete strength in India (IS 516 / IS 456). 2. Recall that the standard cube size specified for the compression test of concrete is 150 mm. 3. Match with the given options to find that option (D) is correct.

Explanation

According to Indian Standards (IS 456 and IS 516), the standard specimen used for testing the compressive strength of concrete is a cube of size 150 mm × 150 mm × 150 mm. This size is chosen considering the maximum size of aggregates typically used in standard structural concrete.

Why the other options are wrong

A: 50 mm is not the standard size for concrete cube testing. B: 70.6 mm cubes are used for testing the compressive strength of cement mortar, not concrete. C: 100 mm cubes are sometimes used when the maximum aggregate size is small, but 150 mm is the primary standard specified by IS codes.

Shortcut

Remember that 150 mm is the standard concrete cube size in India, whereas 70.6 mm is used for cement mortar cube tests.

Common mistake

Confusing concrete cube size (150 mm) with cement mortar cube size (70.6 mm) or smaller 50 mm/100 mm cubes sometimes used for special research or preliminary checks.