Home › MCQs › Civil Engineering › Question #2122
Back to Questions
Civil Engineering QUESTION #2122
Question 1
The water-cement ratio in concrete mix design primarily governs:
  • The workability and unit weight of fresh concrete only
  • Both the compressive strength (inversely — lower w/c gives higher strength per Abrams' law) and durability (lower w/c reduces permeability, carbonation, and chloride ingress) — it is the single most important parameter in concrete mix design✔️
  • Only the setting time and heat of hydration
  • The aggregate-cement ratio and hence the modulus of elasticity
Correct Answer Explanation
Abrams' law: \(f_c = \dfrac{K_1}{K_2^{w/c}}\). Strength decreases as w/c increases because excess water creates capillary pores on evaporation. Durability also decreases with higher w/c as the pore structure becomes more interconnected, allowing aggressive agents to penetrate. Maximum w/c ratios are specified in codes (e.g., 0.45 for moderate exposure in IS 456) — it governs both structural performance and service life.