Los Angeles Abrasion Test: What the Result Means
A percentage loss that estimates how well an aggregate resists wear
How the test works
A weighed sample of coarse aggregate is placed in a rotating steel drum along with a specified number of steel spheres, and the drum is rotated for a set number of revolutions (commonly run per ASTM C131 for smaller aggregate gradations, or ASTM C535 for larger ones). The tumbling and impact from the steel spheres cause the aggregate to abrade and break down.
Calculating the result
After tumbling, the sample is sieved (commonly on a No. 12 sieve) and the material passing that sieve is weighed. The LA abrasion value is the percentage of the original sample weight that passed through the sieve after tumbling — in other words, how much of the material broke down into fine particles during the test.
Interpreting the percentage
A lower percent loss indicates a tougher, more abrasion-resistant aggregate; a higher percent loss indicates a softer, more easily degraded material. Specification limits (the maximum acceptable percent loss for a given application, such as road base versus asphalt surface course) are set by the project or governing agency and vary by intended use — a specific numeric pass/fail threshold should always come from the applicable specification, not assumed.
Worked Example
A 5,000 g original sample; 1,150 g passes the specified sieve after tumbling.
LA abrasion loss = 1,150 ÷ 5,000 × 100 = 23%
Related Calculators
Related Guides
From the Blog
Sources
ASTM C131 / C535
Standard Test Methods for Resistance to Degradation of Small-Size / Large-Size Coarse Aggregate by Abrasion and Impact in the Los Angeles Machine.