Engineering Materials·MCQ explained

As water cement ratio increases, ......... also increases.

Try it first: pick an option, then read the explanation.

Correct answer: D. Workability

Detailed Explanation: W/C Ratio and Workability

Workability is the ease of mixing, transporting, placing, compacting, and finishing fresh concrete. The water-cement ratio is the primary dial that adjusts workability because water acts as the lubricant in the fresh concrete system.

Why D (Workability) is correct: Increasing w/c adds more water per unit of cement. This extra water: reduces inter-particle friction; increases paste volume; makes the mix more fluid (higher slump). All of these raise workability. Option A (compressive strength) decreases with rising w/c — the opposite of what the question asks. Option B (tensile strength) also decreases. Option C (bleeding) does increase with w/c, but the question asks what “also increases” — the most standard and examined answer is workability since Abrams' Law specifically addresses this trade-off.

Effects of Increasing W/C Ratio

PropertyChange
WorkabilityIncreases ↑
BleedingIncreases ↑
Segregation tendencyIncreases ↑
Compressive strengthDecreases ↓
Tensile strengthDecreases ↓
DurabilityDecreases ↓

Key Concepts for Students

  • Workability increases with w/c — the fundamental trade-off between workability and strength in mix design.
  • In mix design (IS 10262), target w/c is set for strength first; then workability is achieved using admixtures (not excess water).
  • Each 25 mm increase in slump requires approximately 3 kg/m³ additional water, raising w/c and reducing strength.