aggregate crushing value test report

Aggregate Crushing Value Test Report: A Complete Guide to Procedure, Results, and Interpretation

The aggregate crushing value (ACV) test is one of the most widely used mechanical tests in civil engineering and construction materials science. It measures the resistance of an aggregate to crushing under a gradually applied compressive load, providing a reliable indicator of aggregate strength and suitability for road construction, concrete production, and other structural applications. This comprehensive guide explains the test procedure, how to prepare an aggregate crushing value test report, how to interpret results, and the standards that govern the test.

What Is the Aggregate Crushing Value Test?

The aggregate crushing value test determines the relative resistance of coarse aggregate to crushing. A prepared sample of aggregate is subjected to a standard compressive load in a steel cylinder, and the percentage of material crushed to a finer size is calculated. A lower ACV indicates stronger, more crush-resistant aggregate, while a higher value indicates weaker material that may degrade under load.

The test is particularly important for:

• Road base and sub-base materials
• Asphalt and bituminous mixes
• Concrete aggregates
• Railway ballast
• Pavement construction quality control

Standards Governing the Test

The most commonly referenced standards for the aggregate crushing value test include:

• BS 812-110: Testing aggregates — Methods for determination of aggregate crushing value
• IS 2386 (Part IV): Methods of test for aggregates for concrete — Mechanical properties
• ASTM D5821 (related aggregate quality assessments)
• AASHTO T 96 (related to Los Angeles abrasion, often used alongside ACV)

The BS 812-110 procedure is the most frequently cited in international aggregate crushing value test reports.

Equipment Required

A standard aggregate crushing value test report should list the apparatus used:

1. Steel cylinder and plunger — conforming to the specified dimensions (typically 150 mm internal diameter)
2. Compression testing machine — capable of applying a uniform load up to 400 kN
3. Weighing balance — accurate to 0.1% of the sample mass
4. Sieve set — including 12.5 mm, 10 mm, and 2.36 mm sieves
5. Oven — capable of maintaining 105–110°C
6. Tamping rod — for compacting the sample
7. Measuring cylinder — for sample volume measurement
8. Trays and containers — for sample handling

Test Procedure Step by Step

The following procedure reflects standard practice for producing a valid aggregate crushing value test report:

1. Sample Preparation

• Collect a representative aggregate sample of sufficient mass (typically 3 kg or more).
• Dry the sample in an oven at 105–110°C to constant mass.
• Sieve the sample to obtain the test fraction, usually passing the 12.5 mm sieve and retained on the 10 mm sieve.
• Record the mass of the prepared test sample.

2. Filling the Cylinder

• Place the cylinder on a level, firm base.
• Fill the cylinder in three layers with the prepared aggregate.
• Tamp each layer with 25 strokes of the tamping rod to ensure uniform compaction.
• Level the surface of the top layer.

3. Applying the Load

• Place the plunger on the surface of the aggregate in the cylinder.
• Position the assembly in the compression testing machine.
• Apply the load uniformly at a rate of approximately 400 kN over 10 minutes (or as specified by the governing standard).
• Release the load and remove the assembly.

4. Sieving and Weighing

• Transfer the crushed material from the cylinder to a tray.
• Sieve the material through the 2.36 mm sieve.
• Weigh the fraction passing the 2.36 mm sieve (crushed fines).
• Weigh the total mass of the test sample.

5. Calculation

The aggregate crushing value is calculated using the formula:

ACV (%) = (Mass of fines passing 2.36 mm sieve / Total mass of test sample) × 100

Sample Aggregate Crushing Value Test Report Format

A professional aggregate crushing value test report typically includes the following sections:

Section	Content
Project Information	Project name, location, client, date
Sample Details	Aggregate source, type, grading, sample identification
Test Standard	BS 812-110, IS 2386, or other applicable standard
Apparatus	List of equipment used with calibration status
Test Conditions	Oven temperature, moisture condition, load rate
Test Data	Initial mass, mass of fines, individual test results
Calculations	ACV for each determination and average value
Results	Final ACV percentage
Remarks	Observations, deviations, compliance statement
Signatures	Technician, reviewer, approving authority

Example Results Table

Determination	Mass of Sample (g)	Mass Passing 2.36 mm (g)	ACV (%)
1	3000	660	22.0
2	3000	690	23.0
3	3000	675	22.5
Average	—	—	22.5

Interpreting Aggregate Crushing Value Results

The ACV result is interpreted against specification limits, which vary by application and standard:

• ACV < 10%: Exceptionally strong aggregate (rare, suitable for high-stress applications)
• ACV 10–20%: Strong aggregate, suitable for wearing courses and high-quality concrete
• ACV 20–30%: Good aggregate, suitable for most road and concrete applications
• ACV 30–45%: Acceptable for lower-stress applications such as sub-base
• ACV > 45%: Weak aggregate, generally unsuitable for structural or wearing course use

For road construction, many specifications require an ACV of 30% or lower for wearing courses and 40% or lower for base courses. Always confirm the applicable limits in the project specification.

Factors Affecting the Aggregate Crushing Value

When reviewing an aggregate crushing value test report, consider these influencing factors:

1. Aggregate mineralogy — Harder minerals such as quartzite and granite produce lower ACV values.
2. Grading and particle size — The test uses a specific size fraction; variations affect comparability.
3. Moisture content — Testing should be performed on oven-dry samples for consistency.
4. Load application rate — Non-uniform loading invalidates results.
5. Sample preparation — Inadequate tamping or non-representative sampling introduces error.
6. Aggregate shape and texture — Flaky or elongated particles tend to crush more readily.

Precision and Repeatability

A reliable aggregate crushing value test report should include duplicate or triplicate determinations. The acceptable variation between individual results depends on the governing standard, but a common practice is to require results within 2–3% of each other. If the variation exceeds the specified tolerance, repeat the test with a fresh sample.

Common Errors and Quality Control Tips

To ensure an accurate and defensible test report:

• Verify the compression machine calibration before testing.
• Use a representative, properly quartered sample.
• Maintain the specified loading rate — typically reaching the target load in about 10 minutes.
• Ensure the cylinder and plunger are clean and undamaged.
• Record all raw data, not just final percentages.
• Include the test standard and any deviations in the report.

Aggregate Crushing Value vs. Other Aggregate Tests

The ACV test is often supplemented by other mechanical tests for a complete aggregate assessment:

• Los Angeles Abrasion Test (ASTM C131/C535) — measures resistance to abrasion and impact
• Aggregate Impact Value Test (BS 812-112) — measures resistance to sudden impact
• Ten Percent Fines Value Test (BS 812-111) — measures resistance to crushing under a specific load
• Water Absorption and Specific Gravity — indicates porosity and durability

Together, these tests provide a comprehensive picture of aggregate quality for specification compliance.

Conclusion

The aggregate crushing value test report is a fundamental document in construction materials testing, providing engineers with quantitative data on aggregate strength. By following standardized procedures, maintaining rigorous quality control, and interpreting results against appropriate specification limits, engineers can confidently select aggregates for roads, concrete, and other structural applications. A well-prepared report — complete with raw data, calculations, apparatus details, and clear conclusions — ensures traceability, supports quality assurance, and protects both designers and contractors in project decision-making.

Whether you are preparing a report for a highway project, a concrete mix design, or a quarry quality assessment, adhering to the procedures and reporting practices outlined in this guide will help you deliver accurate, credible, and specification-compliant results.