Los Angeles abrasion Test on Aggregates

The Los Angeles abrasion test is widely used to evaluate the abrasion resistance and toughness of aggregates. During this test, aggregate samples are subjected to abrasion and impact within a rotating steel drum filled with an abrasive charge of steel balls. As a result, the deterioration of aggregates, including crushing, degradation, and disintegration, is assessed. Primarily, the percentage wear is determined by measuring the loss due to the relative rubbing action between the aggregates and steel balls. Consequently, this test provides a reliable measure of aggregate toughness and abrasion resistance, making it essential for assessing materials used in road construction and other structural applications. Thus, the Los Angeles abrasion test remains a standard method for aggregate quality evaluation.

What is Los Angeles Abrasion Test of Aggregates ?

The Los Angeles abrasion test is a widely adopted method used to determine the abrasion resistance and toughness of aggregates. In this test, aggregate samples are placed in a rotating steel drum with an abrasive charge of steel balls. As the drum rotates, the aggregates undergo abrasion and impact, simulating conditions experienced in road construction and structural applications. The test measures the deterioration of aggregates through crushing, degradation, and disintegration, with the primary objective being to calculate the percentage wear caused by the relative rubbing action between the aggregates and steel balls. The resulting abrasion value provides a reliable indicator of aggregate quality, toughness, and suitability for use in pavement and construction projects.

Significance of Los Angeles Abrasion Test of aggregates

Aggregate is a fundamental and necessary component of concrete, flexible pavements, and other similar structures. More than 70% to 80% of the volume of concrete is aggregate. Quality matters when it comes to aggregates because they are the main component of concrete, flexible pavements, etc. Various tests are conducted to determine the following properties of Aggregates.

• Strength
• Toughness
• Hardness
• Shape
• Water Absorption etc.

The significance of the Los Angeles abrasion test lies in its ability to assess the relative quality, abrasion resistance, and toughness of aggregates used in construction. By simulating the combined effects of abrasion and impact within a rotating steel drum, the test measures how well aggregates withstand mechanical wear, crushing, degradation, and disintegration—factors critical for road construction and structural applications. The resulting abrasion value serves as a key indicator of aggregate durability, helping engineers select materials that ensure pavement longevity and structural integrity. Moreover, the test is essential for quality control and assurance, as it can detect changes in aggregate properties over time, preventing premature pavement failure and excessive dust generation.

Types of aggregate tests

The following are the various aggregate tests used to determine aggregate suitability:

• Crushing strength test
• Los Angeles Abrasion test
• Impact test
• Water absorption test
• Flakiness index test
• Elongation index test
• Bulk-specific gravity test
• Polishing test
• Soundness test on aggregate

This article is about Los Angeles Abrasion tests on aggregates

Los Angeles Abrasion tests on aggregates

The aggregate toughness and abrasion resistance such as crushing, degradation, and disintegration are evaluated by the Los Angeles abrasion test. Generally, this test is performed in accordance with AASHTO T 96 or ASTM C 131.

The Los Angeles Abrasion test determines the aggregate’s wearing resistance and hardness. Abrasion is indeed the wearing action on aggregate caused by vehicle movement. In order to resist abrasion, the aggregate should have an adequate abrasion value. The abrasion test value can ensure the quality and suitability of aggregates. Furthermore, aggregate with high abrasion resistance has a long life span.

Codes and standards for Los Angeles Abrasion test of aggregates

The Los Angeles abrasion test of aggregates is standardized by several codes and standards. In India, IS 2386 (Part IV):1963 specifies the methods for testing the mechanical properties of aggregates, including abrasion resistance. Additionally, IS 383-1970 covers specifications for coarse and fine aggregates. Internationally, ASTM C131 and ASTM C535 are widely referenced standards for conducting the Los Angeles abrasion test on aggregates used in construction.

Working principle of LA Abrasion test

The working principle of the Los Angeles abrasion test is based on determining the percentage wear of aggregates due to the relative rubbing and impact action between the aggregate particles and steel balls inside a rotating drum. Aggregates are placed in the drum with a specified abrasive charge and rotated at 30–33 rpm for a set number of revolutions, depending on aggregate grading. During rotation, the aggregates experience repeated impact and abrasion, simulating real-world mechanical wear. After completion, the sample is sieved, and the loss in weight is measured. The percentage loss, known as the abrasion value, reflects the aggregate’s resistance to abrasion, toughness, and overall durability.

The test procedure for the Los Angeles Abrasion test of aggregate

Los Angeles Abrasion Test Procedure (as per IS 2386 Part IV:1963)

Sample Preparation

As per IS 2386 (Part IV):1963, aggregate samples are oven-dried at 105–110°C to a constant weight. The sample must conform to one of the specified gradings (A to G) as shown in Table II (IS 2386 Part IV):

Grading	Sieve Size Passing (mm)	Sieve Size Retained (mm)	Weight of Test Sample (g)	Number of Steel Balls (Abrasive Charge)
A	80	63	5000	12
B	63	50	5000	11
C	50	40	5000	8
D	40	25	5000	6
E	25	20	5000	6
F	20	12.5	5000	6
G	12.5	10	5000	6

Abrasive Charge

Select the number and weight of steel balls (abrasive charge) according to the grading (see above table). Each steel ball should be approximately 48 mm in diameter and weigh between 390 and 445 grams (IS 2386 Part IV, Clause 5.3.2).

Loading the Machine

Place the dried aggregate sample and the abrasive charge into the Los Angeles abrasion testing machine, which has a horizontal rotating drum with an internal shelf (IS 2386 Part IV, Clause 5.3.1).

Rotation

Seal the drum and rotate it at 20–33 revolutions per minute. For gradings A–D, rotate for 500 revolutions; for gradings E–G, rotate for 1,000 revolutions (IS 2386 Part IV, Table II).

Separation and Sieving

After rotation, discharge the material and sieve it first with a sieve coarser than 1.70 mm IS sieve, then with a 1.70 mm IS sieve (IS 2386 Part IV, Clause 5.3.4).

Washing and Drying

Wash and oven-dry the material retained on the 1.70 mm IS sieve at 105–110°C to constant weight. Weigh this retained fraction to the nearest gram.

Calculation

Calculate the percentage loss in mass as the Los Angeles abrasion value using the formula (IS 2386 Part IV, Clause 5.3.5):Los Angeles Abrasion Value (%)=A−BA×100Los Angeles Abrasion Value (%)=AA−B×100

Where:

• AA = Original weight of the oven-dried sample (g)
• BB = Weight of the fraction retained on the 1.70 mm IS sieve after the test (g)

References:

• IS 2386 (Part IV):1963 – Methods of Test for Aggregates for Concrete, Part IV: Mechanical Properties
• IS 383:1970 – Specification for Coarse and Fine Aggregates from Natural Sources for Concrete

This standardized procedure ensures accurate and consistent assessment of aggregate abrasion resistance and toughness for use in road and structural applications.

Los Angeles (LA) Abrasion Test as per ASTM Standards

Purpose:
The Los Angeles (LA) abrasion test evaluates the toughness and abrasion resistance of coarse aggregates, crucial for their suitability in road construction and other engineering applications.

Applicable ASTM Standards:

• ASTM C131: For coarse aggregates smaller than 37.5 mm (1.5 inches).
• ASTM C535: For coarse aggregates larger than 19 mm (3/4 inch).
• Aggregates between 19 mm and 37 mm can be tested under either standard.

Test Procedure (as per ASTM C131/C535)

1. Sample Preparation:
   • Select and prepare a specified mass of aggregate according to the aggregate size being tested.
2. Equipment:
   • Use the Los Angeles abrasion machine: a rotating steel drum with an internal shelf and a specified number of steel balls (abrasive charge).
   • The drum rotates at 30–33 revolutions per minute.
3. Test Execution:
   • Place the aggregate sample and steel balls in the drum.
   • Rotate the drum for 500 revolutions.
   • After rotation, remove the sample and separate it using a No. 12 sieve (1.70 mm opening).
4. Calculation:
   • Weigh the fraction of aggregate retained on the sieve. Calculate the percentage loss in mass, which represents the aggregate’s resistance to abrasion and impact.

5. Reporting

• Report the grading of the test specimen and the percent wear after 500 revolutions.

Acceptance Criteria

• Maximum allowable loss:
  • Base course: 45% loss (maximum)
  • Surface course: 35% loss (maximum)

Key Takeaways

The Los Angeles abrasion test is a crucial method for evaluating the abrasion resistance and toughness of aggregates, which are essential for concrete and pavement durability. By simulating real-world wear through abrasion and impact in a rotating drum with steel balls, this test measures aggregate deterioration, including crushing and disintegration. The resulting abrasion value serves as a key indicator of aggregate quality, helping engineers select materials suitable for road construction and structural applications. The test is standardized internationally by ASTM C131 and C535, and in India by IS 2386 (Part IV):1963. Accurate sample preparation, specified abrasive charge, and controlled test conditions ensure reliable results, making the LA abrasion test vital for quality control and assurance in construction projects1.

Conclusion

The Los Angeles abrasion test remains a standard and indispensable procedure for assessing the mechanical durability of aggregates used in concrete and flexible pavements. Its ability to replicate the combined effects of abrasion and impact provides a reliable measure of an aggregate’s resistance to mechanical wear, ensuring long-lasting performance in demanding environments. By quantifying percentage wear, the test helps prevent premature pavement failures and excessive dust generation, contributing to safer and more durable infrastructure. Adherence to recognized standards like ASTM C131 and IS 2386 guarantees consistency and comparability of results, reinforcing the test’s role in material selection and quality assurance for civil engineering projects.