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. Take 500 g of aggregate passing 12.5 mm sieve and retained on 10 mm sieve.
2. Fill the cylindrical mould in three layers, tamping each layer 25 times.
3. Place the mould on the base plate of the impact testing machine.
4. Apply 15 blows using a 14 kg hammer dropped from a height of 38 cm.
5. Remove the sample and sieve it through a 2.36 mm sieve.
6. Weigh the fines passing 2.36 mm sieve (W₂).
7. Record the original oven-dry weight of the sample (W₁).

Observations & Sample Table

Average AIV = 15.2% (Suitable for wearing surfaces)

Calculations & Formula

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

Limits & Interpretation

• Wearing surfaces: AIV ≤ 30%
• Other concrete works: AIV ≤ 45%

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.