AGGREGATE IMPACT VALUE TEST-10+ IMPORTANT NOTES TO REMEMBER

1. Aggregate impact value test gives an indication of aggregate’s toughness property (i.e. property of a material to resist impact)
2. Aggregate impact values are used to classify the stone aggregates with respect to toughness property as given below.

3. The test equipment and the test procedure are quite simple and it determines the resistance to impact of stone aggregates simulating field condition.
4. This test can be performed even at construction site or at stone quary, as the apparatus is simple and portable.
5. Aggregate impact value test also gives an indirect indication of the strength characteristics of aggregate.
6. Aggregate impact value of a sample also depends on the shape factors such as flakiness index and elongation index of the aggregates.
7. It has been found that for majority of aggregates, the aggregate crushing value and aggregate impact values are numerically similar within close limits.
8. For deciding the suitability of soft aggregates in base course construction, aggregate impact test is commonly used.
9. A modified impact test is also often carried out in the case of soft aggregates to find the wet impact value after soaking the test sample in water.
10. Maximum allowable aggregate impact value of aggregate in different types of pavement material / layers as per IRC is as below

13. Aggregate impact valuesof soft aggregates for road constructions are as follows