Aggregate should have the following qualities
Quality Requirements of Aggregate
- Aggregates should be strong, hard, dense, durable, clear and free from veins and adherent coating.
- Aggregates should be free from injurious amounts of disintegrated pieces, alkalis, vegetable matter and other deleterious substances.
- Flaky and Elongated pieces should not be present in aggregate mass.
- Aggregate crushing value should not exceed 45 percent for aggregate used for concrete other than for wearing surfaces, and 30 percent for concrete for wearing surfaces, such as runways, roads and pavements.
- Aggregate impact value should not exceed 45 percent by weight for aggregates used for concrete other than for wearing surfaces and 30 percent by weight for concrete for wearing surfaces, such as runways, roads and pavements.
- Abrasion value of aggregate when tested using Los Angeles machine, should not exceed 30 percent by weight for aggregates to be used in concrete for wearing surfaces and 50 percent by weight for aggregates to be used in other concrete.
- For concrete liable to be exposed the action of frost, coarse and fine aggregates shall pass a sodium or magnesium sulphate accelerated test. Generally the average loss of weight, after 5 cycles of sodium or magnesium suphate accelerated test, should not exceed the following.
|For fine aggregate
||10% when tested with sodium sulphate solution
15% when tested with magnesium sulphate solution
|For coarse aggregate
||12% when tested with sodium sulphate solution
18% when tested with magnesium sulphate solution