Los Angeles Abrasion Testing Machine in Civil Engineering

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Working of Los Angeles Abrasion Testing Machine for aggregate testing in Civil Engineering​

The Los Angeles Abrasion Testing Machine is one of the most important laboratory devices used in civil engineering for testing construction materials. It is specifically designed to evaluate the hardness, toughness, and abrasion resistance of aggregates, which are widely used in roads, pavements, and concrete structures.
In highway engineering and material testing laboratories, this machine plays a vital role in determining whether a particular aggregate is suitable for construction purposes. The test conducted using this machine is known as the Los Angeles Abrasion Test, which was developed in the 1920s to assess the durability of aggregates under simulated conditions.

Purpose of the Machine​

The Los Angeles Abrasion Testing Machine is used for several key purposes:

• To measure the wear and tear resistance of aggregates
• To determine the quality of aggregates for road construction
• To calculate the Los Angeles Abrasion Value (%)
• To simulate real-life conditions such as traffic friction and impact

In general, strong aggregates have a lower abrasion value, which makes them more suitable for construction work.

Main Parts of the Los Angeles Abrasion Testing Machine​

The machine consists of the following essential components :

• Rotating steel drum (cylinder)
• Electric motor with gear system
• Steel balls (abrasive charge)
• Tray for collecting material
• Revolution counter

During the test, the drum rotates at a speed of about 30–33 revolutions per minute (rpm).

Working Principle of Los Angeles Abrasion Testing Machine​

The working of the machine is based on a combination of abrasion and impact action:

• Aggregates along with steel balls are placed inside the drum
• The drum rotates continuously
• Materials are lifted and then fall inside the drum
• This repeated motion causes wear, crushing, and grinding of aggregates

The percentage loss in weight after the test gives the abrasion value, which indicates the strength of the aggregate.

Test Procedure of Los Angeles Abrasion Testing Machine​

The Los Angeles Abrasion Test is performed in a systematic step-by-step manner:

Step 1: Sample Preparation of Los Angeles Abrasion Testing Machine​

• A clean and dry aggregate sample is taken
• The initial weight is measured as W₁

Step 2: Loading of aggregate material and Steel Balls​

• The aggregates and steel balls are placed inside the drum

Step 3: Rotation of aggregate material​

• The drum is rotated for 500 to 1000 revolutions

Step 4: Sieving of aggregate material​

• The aggregate material is removed and sieved through a 1.7 mm sieve

Step 5: Final Weight of aggregate material​

- The remaining aggregate is weighed as W₂

Step 6: Calculation of abrasion value​

The abrasion value is calculated as:

Standard Values (Important for Exams)
The suitability of aggregates is judged based on abrasion value:

• ≤ 30% → Excellent (used for wearing surfaces)
• ≤ 35% → Good (suitable for road surfaces)
• ≤ 45% → Acceptable (used for base layers)

A higher abrasion value indicates weaker aggregates.

Applications of Los Angeles Abrasion Testing Machine​

The Los Angeles Abrasion Testing Machine is widely used in:

• Road construction (highways and pavements)
• Railway ballast testing
• Concrete mix design
• Quality control in construction laboratories

The Los Angeles Abrasion Testing Machine is an essential tool in civil engineering that ensures the durability and strength of aggregates used in construction. By simulating real-world conditions such as traffic load and impact, it helps engineers select the most suitable materials for long-lasting and safe infrastructure.
Understanding this test is crucial for students and professionals, as it directly influences the quality and performance of roads and structural works.