---
title: "Aggregate crushing value test"
subject: "Transportation Engineering I"
chapter: 6
key: "semester_6/transportation_engineering_i:crushing-value"
source: https://www.bctengineer.com/q/semester_6/transportation_engineering_i/crushing-value
site: BCT Engineering
---

# Aggregate crushing value test

Transportation Engineering I · Chapter 6: Highway Materials

- Asked in: 2077 Chaitra, 4 marks; 2076 Baisakh; 2076 Bhadra; 2073 Bhadra, 4 marks; 2072 Magh; 2064 Shrawan (old course); 2063 Kartik (old course), 1+5+2 marks (asked 7 times)
- Video: [AGGREGATE CRUSHING VALUE TEST || Crushing test ! Crushing test of aggregate ! Test of aggregate](https://www.youtube.com/watch?v=SyOFfoi8Br8) — Crazy Civil Engineering
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/transportation_engineering_i/crushing-value
- Whole chapter: https://www.bctengineer.com/md/semester_6/transportation_engineering_i/chapter-6

## Question

Explain the crushing value test of road aggregate: the laboratory procedure and its significance.

## Short answer

Oven-dried 12.5–10 mm aggregate is placed in a cylinder and a load of 40 tonnes is gradually applied over 10 minutes. The crushed material is sieved on 2.36 mm; ACV = (weight passing / original weight) × 100%. It measures compressive strength; limits are ≤30% for wearing course, ≤45% for base.

## Answer

#### Definition
The **aggregate crushing value (ACV)** is the percentage by weight of fines (passing the 2.36 mm IS sieve) produced when a sample of aggregate is crushed under a gradually applied load of 40 tonnes in a standard cylinder. It is a measure of the **strength** of the aggregate against crushing under a slowly applied (compressive) load (IS:2386 Part IV).

#### Apparatus
- Steel cylinder (mould) of 15.2 cm internal diameter with a base plate and a plunger (14.9 cm), and a tamping rod 16 mm in diameter and 45-60 cm long with a rounded end.
- Compression testing machine of 40 t capacity, IS sieves 12.5, 10 and 2.36 mm, balance (to 1 g), and a cylindrical measure 11.5 cm in diameter and 18 cm high.

#### Procedure
1. Take oven-dried aggregate **passing the 12.5 mm and retained on the 10 mm IS sieve**; fill the cylindrical measure in three layers, tamping each with 25 strokes, and strike off. Weigh the sample ($W_1$, about 3 kg).
2. Place the aggregate in the cylinder in three layers, each tamped 25 times, level the surface and insert the plunger.
3. Place the assembly in the compression testing machine and apply the load at a uniform rate so that **40 tonnes is reached in 10 minutes** (4 t/min); then release it.
4. Remove the crushed material and sieve it through the **2.36 mm IS sieve**; weigh the fraction passing ($W_2$) and the fraction retained.

$$
\text{ACV} = \frac{W_2}{W_1}\times 100\%
$$

The average of two tests is reported.

#### Significance and limits
- Low ACV = strong aggregate; high ACV = weak aggregate that crushes under load.
- Limits (IRC/NRS 2070): **not more than 30%** for wearing courses (bituminous surface, cement concrete) and **not more than 45%** for bituminous base and WBM base courses.
- Typical values: ACV below 10% is exceptionally strong, 10-20% strong, 20-30% satisfactory, above 35% weak.
- For aggregates with ACV above 30%, the ten per cent fines value is used instead.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What is the aggregate crushing value?
   A. Percentage of fines passing 2.36 mm after crushing under 40 tonnes
   B. Percentage retained on 12.5 mm
   C. Loss in weight after 500 revolutions
   D. Depth of penetration
   Answer: A. ACV = W2/W1 x 100, where W2 is the material passing the 2.36 mm sieve. (Key point: Definition of ACV)

2. Which size of aggregate is used in the crushing test?
   A. Passing 12.5 mm and retained on 10 mm
   B. Passing 20 mm retained on 12.5 mm
   C. Passing 2.36 mm
   D. Any size
   Answer: A. The standard sample is 12.5-10 mm, filled in three layers with 25 tamping strokes each. (Key point: Test sample)

3. What do the limits for ACV mean?
   A. Low ACV is strong aggregate; not more than 30% for wearing course
   B. High ACV is strong aggregate
   C. Not more than 45% for wearing course
   D. ACV has no use in design
   Answer: A. Lower ACV means stronger aggregate; wearing course 30% max and base 45% max. (Key point: Significance and limits)

## Related in Transportation Engineering I

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## Related in other subjects

- [Aggregate crushing value determination](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Aaggregate-crushing-value) — Concrete Technology and Masonry Structure, chapter 1
- [Procedure: test of significance of mean](https://www.bctengineer.com/question.md?key=semester_5%2Fprobability_and_statistics%3Atest-of-significance-mean-procedure) — Probability and Statistics, chapter 6
- [Soundness test of cement and procedure](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Acement-soundness-test-procedure) — Civil Engineering Materials, chapter 5
- [Short note: construction procedure of gravel road](https://www.bctengineer.com/question.md?key=semester_7%2Ftransportation_engineering_ii%3Agravel-road-construction-procedure) — Transportation Engineering II, chapter 3, asked 2×