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As per IRC, in wearing coarse of pavement, the aggregate impact value should not exceed
35.00%
35%
30.00%
30%
30.00%
40%
50.00%
50%
30.00%
30%
According to the Indian Roads Congress (IRC) specifications, the Aggregate Impact Value (AIV) for aggregates used in the wearing course of pavement should not exceed 30%. This test measures the toughness of aggregates, which is the ability of the material to resist sudden shock or impact loading.
According to the Indian Roads Congress (IRC) specifications, the Aggregate Impact Value (AIV) for aggregates used in the wearing course of pavement should not exceed 30%. This test measures the toughness of aggregates, which is the ability of the material to resist sudden shock or impact loading.
AIV=W1тАЛW2тАЛтАЛ├Ч100
Where W2тАЛ is weight of fines passing 2.36 mm sieve and W1тАЛ is original oven-dry weight.
The Aggregate Impact Test is performed by subjecting a standard size aggregate sample (10mm to 12.5mm) to 15 blows of a 13.5-14 kg hammer falling from a height of 380mm ┬╖ The ratio of the weight of the fraction passing the 2.36mm IS sieve to the total weight of the test sample gives the impact value ┬╖ A higher value indicates greater brittleness and lower toughness of the stone aggregate.
Test apparatus is known as the Impact Testing Machine.
The test evaluates toughness of aggregates under dynamic loading.
For bituminous macadam or surface dressing, 30% is the standard limit.
Lower AIV corresponds to superior quality/toughness.
Simple test procedure.
Effective assessment of resistance to impact loads.
Cannot replace Los Angeles Abrasion test for long-term wear.
High sensitivity to operator technique and impact uniformity.
Quality control of highway construction materials.
Pavement design for heavy traffic loads.
For water-bound macadam (WBM) base course, the limit is 40%.
For bituminous macadam, the threshold of 30% is strictly enforced to ensure durability under vehicular traffic impact.
Option A (35%) is sometimes used for lower category roads, but 30% is the standard regulatory value for wearing courses.
B is correct тАФ As per IRC standards, the aggregate impact value for wearing courses must not exceed 30%.
Remember: AIV measures toughness (impact), whereas Los Angeles Abrasion measures both hardness (attrition) and toughness (impact) ┬╖ Always distinguish between surface courses (stricter 30%) and base courses (more lenient 40-45%).