Los Angeles Abrasion Test: What the Result Means
A percentage loss that estimates how well an aggregate resists wear
What your LA abrasion value means
The LA abrasion value is the percentage of the original sample that broke down finer than the No. 12 (1.70 mm) sieve during the test. A value of 42 means 42% of the sample's mass broke down finer than the No. 12 sieve, so a lower number means a tougher aggregate.
Whether a value passes depends on the specification for the use, not on a universal cut-off. ASTM C33 allows up to 50% loss for concrete coarse aggregate, most US state asphalt specifications set 40% or 45%, and stone-matrix asphalt is held to 30%.
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. The gradings, sphere charges and revolutions are covered in What Does the Los Angeles Abrasion Test Measure?.
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.
In practice the coarse fraction is the part that gets washed, dried and weighed, so the formula is usually written as LA abrasion value (%) = (original mass − mass retained on the No. 12 sieve) ÷ original mass × 100. The LA Abrasion Value Calculator uses this form and reports the raw loss, leaving the pass/fail decision to your specification.
Typical specification limits
The limits below show how widely requirements vary. Always confirm the number, and the test method and grading it refers to, in the specification that governs your project.
| Use | Specification | Maximum LA loss |
|---|---|---|
| Coarse aggregate for concrete | ASTM C33 | 50% |
| Coarse aggregate for hot-mix asphalt | US state highway specifications | Most 40% or 45%; the range runs from 25% to 55% |
| Stone-matrix asphalt (SMA) | AASHTO | 30% |
| Superpave asphalt mixes | No national LA limit | Set by each agency |
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.
Read against the limits in the table above, results fall into four broad bands.
30% or less
Within ASTM C33, the 30% stone-matrix asphalt limit and most state asphalt limits, though a result above 25% can still fail the strictest state limits. Hard igneous rock such as basalt often tests in this range.
Above 30% and up to 45%
Within ASTM C33 but over the SMA maximum. Up to 40% is within the most common state asphalt limits; between 40% and 45%, the same result passes in some states and fails in others.
Above 45% and up to 50%
Still within the ASTM C33 limit for concrete coarse aggregate, but over the most common asphalt limits.
Above 50%
Over the ASTM C33 limit and most asphalt limits; only the most lenient state limits reach 55%. Soft limestones and sandstones can test around 60%.
Typical values by rock type
Rock type gives a rough idea of what to expect, but the ranges overlap and quality varies within every rock type, so a quarry's own test results govern.
| Rock type | Typical LA loss (%) |
|---|---|
| Basalt | 10–17 |
| Dolomite | 18–30 |
| Limestone | 19–30 |
| Quartzite | 20–35 |
| Granite | 27–49 |
| Gneiss | 33–57 |
When the LA value can mislead
The test is empirical, and its link to field performance is weak. Some aggregates, including slag and some limestones, show a high LA loss yet perform adequately in pavements, while the result tracks reasonably well with how much dust an aggregate produces during handling and asphalt production.
For that reason some agencies add or substitute other tests. The Micro-Deval test (ASTM D6928) tumbles aggregate with water and small steel balls and tends to polish particles rather than break them; research cited by Pavement Interactive found it predicted field toughness and abrasion resistance better, and Maine uses it in place of the LA test. Sulfate soundness (ASTM C88) addresses weathering, which the LA test does not.
Worked Example
An illustrative borderline result: a 5,000 g Grading B sample retains 2,900 g on the No. 12 sieve after 500 revolutions.
Material passing the No. 12 sieve: 5,000 − 2,900 = 2,100 g
LA abrasion loss = 2,100 ÷ 5,000 × 100 = 42%
Against ASTM C33 (50% for concrete coarse aggregate): within the limit
Against a 45% state asphalt limit: within; against a 40% state asphalt limit: over
Against the 30% stone-matrix asphalt limit: over
So the same 42% aggregate is acceptable under one specification and rejected under another — there is no universal pass/fail value
FAQ
- What is a good LA abrasion value?
- Lower is better, but 'good' means within the specification for the use. ASTM C33 allows up to 50% for concrete coarse aggregate, most state asphalt specifications allow 40% or 45%, and stone-matrix asphalt is limited to 30%.
- Is a higher LA abrasion value better or worse?
- Worse. The value is the percentage of the sample that broke down during the test, so a higher number means a softer aggregate that degrades more under impact and wear.
- Can I compare an ASTM C131 result with an ASTM C535 result?
- Not directly. The two methods use different sample sizes, gradings and numbers of revolutions, so a specification limit written for one method should not be applied to a result from the other.
- Does a low LA abrasion value guarantee good field performance?
- No. The test is a screening tool with a weak link to field performance. Specifications often pair it with other tests, such as sulfate soundness or Micro-Deval.
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.
ACI Education Bulletin E1-07, Aggregates for Concrete
Section 3.6, abrasion and impact resistance, including the ASTM C33 maximum loss of 50%.
ACI Education Bulletin E1-07, Aggregates for Concrete — referencePavement Interactive, Los Angeles Abrasion
Asphalt specification ranges, typical values by rock type, test limitations and the Micro-Deval comparison.
Pavement Interactive, Los Angeles Abrasion — reference