Aggregate Impact Value Test – IS 2386 Procedure, Formula & Limits

IS Code: IS 2386 (Part IV) | Last Updated: 11 Dec 2025 | Author: Kishor Kumar

Quick Summary

• Aim: Determine Aggregate Impact Value (AIV) to assess aggregate toughness
• IS Code: IS 2386 Part IV
• Sample Size: 10–12.5 mm aggregates
• Result: Percentage of fines generated due to impact

Objective

The Aggregate Impact Value (AIV) Test evaluates toughness and durability of aggregates. This guide per IS 2386 provides procedure, apparatus, calculation, and permissible limits, making it site-ready for engineers and QA/QC teams ensuring strong and long-lasting pavement layers.

Apparatus Required

• Aggregate Impact Testing Machine (IS 2386 Part IV)
• Cylindrical mould with base plate
• Tamping rod
• Sieve set (12.5 mm, 10 mm, 2.36 mm)
• Weighing balance
• Oven (optional)
• Aggregate sample (10–12.5 mm size)

Step-by-Step Procedure

1. The test sample consists of aggregates passing 12.5 mm sieve and retained on 10 mm sieve, and dried in an oven for four hours at a temperature of 100°C to 110°C and then cooled.
2. Test aggregates are filled in three layers in the cylindrical measure and tamped 25 times with the rounded end of the tamping rod.
3. The net weight of the aggregates in the measure is determined to the nearest gram.
4. The cup is fixed firmly on the base of the machine and the entire test sample from the cylindrical measure is transferred to the cup and compacted by tamping with 25 strokes.
5. The Standard hammer (tamping hammer) weight is 13.5 kg to 14 kg is raised until its lower face is 380 mm above the upper surface of the aggregates in the cup and allowed to fall freely on the aggregates.
6. The test sample is subjected to a total of 15 blows, each delivered at an interval of not less than one second.
7. The crushed aggregate is then removed from the cup and sieved on the 2.36 mm sieve until no further significant amount passes.
8. The fraction passing the sieve is weighed to an accuracy of 0.1 g. The fraction retained on the sieve is also weighed, and the total of both fractions should not be less than the original specimen weight by more than one gram.
9. If the total weight is less than the original by more than one gram, the results should be discarded and a fresh test must be conducted.

Observations & Sample Table

Average AIV = 15.2% (Suitable for wearing surfaces)

Calculations & Formula

Aggregate Impact Value (AIV):
AIV (%) = (W₂ / W₁) × 100

Limits & Interpretation

• < 10% — Exceptionally Strong
• 10% – 20% — Strong
• 20% – 30% — Satisfactory for road surfacing
• > 35% — Weak for road surfacing

Lower AIV values indicate stronger and tougher aggregates. High AIV values indicate weak aggregates unsuitable for heavy traffic pavements.

Frequently Asked Questions (FAQ)

What is Aggregate Impact Value?

Aggregate Impact Value (AIV) is the percentage of fines produced when aggregates are subjected to sudden impact loading. It indicates the toughness and durability of aggregates used in pavement construction.

Which IS code specifies the AIV test?

The Aggregate Impact Value test is specified under IS 2386 (Part IV), which provides the standard procedure for determining aggregate impact resistance.

How is the AIV test performed?

Aggregates are placed in a standard cylindrical mould and subjected to 15 blows of a hammer. The material passing through the 2.36 mm sieve is weighed to calculate the impact value.

Why is the AIV test important?

The test ensures that aggregates are tough enough to resist impact loads from traffic, preventing premature pavement failure.

What is the permissible limit of AIV?

For wearing surfaces, AIV should be less than 30%. For other concrete works, it should generally be less than 45%, as per project specifications.

HowTo: Perform AIV Test Quickly

1. Prepare 500 g aggregate sample (10–12.5 mm).
2. Fill mould in 3 layers and tamp each layer 25 times.
3. Apply 15 hammer blows from 38 cm height.
4. Sieve through 2.36 mm and weigh fines.
5. Calculate AIV and compare with limits.
6. Repeat for 3 trials and take average.