Which of the following tests is NOT used to test aggregate for its abrasion resistance in concrete works?
Correct Answer: C. Soundness test
📚 Detailed Explanation: Soundness Test Measures Weathering Resistance, NOT Abrasion
Why C (Soundness test) is correct (the answer to “which is NOT an abrasion test”): The soundness test assesses the resistance of aggregate to disintegration caused by weathering (freeze-thaw cycles, sulphate crystallisation). It has nothing to do with abrasion from mechanical wear. The other three tests — Los Angeles, Deval, and Dorry — all measure how much material is lost due to abrasive wear and impact.
Aggregate Abrasion Resistance Tests
| Test | Standard | Principle | Abrasion Test? |
|---|---|---|---|
| Los Angeles Abrasion Test | IS 2386 Part 4 | Aggregate + steel balls rotated in drum for 500 revolutions; measure % loss by weight | ✓ YES — abrasion + impact |
| Deval Attrition Test | IS 2386 Part 4 | Aggregate rotated in smooth drum (no balls) for 10,000 revolutions; measure % loss | ✓ YES — attrition/abrasion |
| Dorry Abrasion Test | IS 2386 Part 4 | Aggregate pressed against rotating steel disc with sand abrasive; measure weight loss | ✓ YES — surface abrasion |
| Soundness Test | IS 2386 Part 5 | Aggregate submerged in Na2SO4 or MgSO4 solution; crystallisation pressure mimics freeze-thaw; measure % loss | ✗ NO — weathering/disintegration test |
Los Angeles Abrasion Test Details (Most Common)
| Aspect | Detail |
|---|---|
| Equipment | Rotating steel drum (diameter 711 mm, length 508 mm) with steel balls |
| Sample | Graded aggregate (dependent on grading group A–G per IS 2386) |
| Revolutions | 500 (for coarse aggregate); 1000 (for fine aggregate) |
| Result | Los Angeles Abrasion Value (%) = (loss in weight / original weight) × 100 |
| Limits | IS 456: max 30% for concrete wearing surfaces; 50% for ordinary concrete |
- Soundness test (IS 2386 Part 5) = weathering resistance test; NOT an abrasion test.
- Abrasion tests: Los Angeles (most common), Deval attrition, Dorry abrasion — all measure mechanical wear.
- Los Angeles value ≤30% required for concrete pavement wearing surfaces (IS 456).