Concrete Mix Design MCQ with answer and solution

Concept

Water-cement ratio is the ratio of the weight of water to the weight of cement in a concrete mix.

Formula

w/c = W_water / W_cement

Step-by-step solution

1. The w/c ratio is defined by mass (weight). 2. Water is in the numerator and cement is in the denominator. 3. So w/c = Weight of water / Weight of cement. 4. Example: 0.5 means 0.5 kg of water for every 1 kg of cement.

Explanation

The water-cement ratio compares the mass of water with the mass of cement in the mix. It is the main factor that controls concrete strength (Abrams' law). A lower w/c ratio usually gives higher strength.

Why the other options are wrong

A and C: These are inverted (cement/water), so they are wrong. B: It mixes volume with weight. The standard definition uses weight for both.

Shortcut

Write 'w' over 'c' in the same order as the name: water over cement, both by weight.

Common mistake

Choosing B because 1 litre of water weighs about 1 kg. The correct definition is still by weight.