The condition not applicable to water cement ratio law is …………….
Correct Answer: B. Concrete specimens may be tested at any temperature
📚 Detailed Explanation: Conditions for Applicability of W/C Law
Abrams' Water-Cement Ratio Law applies only under specific controlled conditions. Testing outside these conditions gives misleading results that do not follow the law.
Why B is NOT applicable (= correct answer): The w/c law requires specimens to be tested at a standard temperature. Temperature affects the rate of hydration — higher temperature accelerates early hydration (higher early strength) but may reduce long-term strength due to a coarser gel structure. If specimens are tested at different temperatures, the strength values will not reflect only the w/c ratio effect. Therefore “may be tested at any temperature” violates the law's conditions.
Option A (moisture continuity) — valid condition: concrete must remain moist (cured) continuously for hydration to proceed and strength to develop fully.
Option C (same age) — valid condition: strength increases with age; specimens must be the same age for w/c comparison.
Option D (same size) — valid condition: specimen size affects measured strength (size effect); same-size specimens must be used.
Valid Conditions for Abrams' W/C Law
| Condition | Required? | Reason |
|---|---|---|
| Continuous moist curing | Yes | Hydration must not stop |
| Same age at testing | Yes | Strength varies with age |
| Same specimen size | Yes | Size effect on measured strength |
| Standard temperature | Yes (fixed, not “any”) | Temperature alters hydration rate |
Key Concepts for Students
- “Any temperature” violates the w/c law — a specific standard temperature is required.
- IS 516 requires concrete cube testing at 27 ± 2°C in India; BS/EN use 20°C.
- Steam curing at elevated temperatures accelerates strength gain but changes the strength-w/c relationship.