Experimental water absorption tests are done on fine aggregates to find the:
Correct Answer: A. Only (i), (ii) and (iii)
📚 Detailed Explanation: Purpose of Water Absorption Tests on Fine Aggregates
The water absorption test (IS 2386 Part III) measures the percentage of water absorbed by aggregate over 24 hours. The results reveal several important aggregate properties.
Why A (Only i, ii, and iii) is correct:
(i) Water holding capacity — directly measured. High absorption = high porosity = high water holding.
(ii) Strength of material — indirectly indicated. Porous aggregates with high absorption tend to be weaker (more internal voids). High absorption (>2%) signals potentially weak aggregate.
(iii) Quality of material — absorption is a quality indicator per IS 383. Low absorption = sound, dense aggregate = high quality.
(iv) Shape — NOT determined by absorption. Shape requires flakiness index test (IS 2386 Part I) or elongation index test.
(i) Water holding capacity — directly measured. High absorption = high porosity = high water holding.
(ii) Strength of material — indirectly indicated. Porous aggregates with high absorption tend to be weaker (more internal voids). High absorption (>2%) signals potentially weak aggregate.
(iii) Quality of material — absorption is a quality indicator per IS 383. Low absorption = sound, dense aggregate = high quality.
(iv) Shape — NOT determined by absorption. Shape requires flakiness index test (IS 2386 Part I) or elongation index test.
What Water Absorption Test Indicates
| Parameter | Determined? | Limit (IS 383) |
|---|---|---|
| Water holding capacity | Yes (directly) | — |
| Strength (indirectly) | Yes (porosity proxy) | <2% for coarse; <3% for fine |
| Quality | Yes (soundness proxy) | Lower = better |
| Shape | No | Use flakiness/elongation test |
- Water absorption <2% for coarse aggregate and <3% for fine aggregate is generally acceptable per IS 383.
- Aggregate shape is tested separately using flakiness index (<35%) and elongation index (<45%) tests.