The Los Angeles (LA) Abrasion Test is a widely used method to assess the toughness and abrasion characteristics of construction aggregates.
About the LA Abrasion Testing Apparatus
The LA Abrasion Testing Apparatus is made up of a drum with an inside diameter of 710mm ± 2mm and an inside length of 510 ± 2mm. The cylinder will have an opening for the insertion of the test sample. Inside the cylinder shall be a shelf projecting radially into the drum 90mm in length 25mm in thickness. The machine shall also be able to maintain a substantially uniform peripheral speed. And shall rotate at speed between 30 and 33 rotations per minute for the full period of the test.
In conjunction with the drum is not less than 12 spherical balls as a charge for the cylinder. Each ball will be approximately 48mm in diameter with a mass of 417g ± 27.5g.
How an LA Abrasion Test is Conducted
- Check and record the initial mass of the sample to the nearest gram.
- Select and make up the appropriate steel charge.
- Inspect the inside of the LA machine for cleanliness and brush out any old residue if necessary.
- Seal the sample in the cylinder and place the cover on the opening, ensuring it is tightly sealed.
- Set the number of revolutions (this will depend on gradings).
- On completion of the revolutions. Open the cover plate and extract the sample and steel balls. Place them all in a tray.
- Any excess that may be stuck in the cylinder can be removed by hitting the cylinder with a rubber mallet. Clean the fines from the interior thoroughly with a soft brush into the tray also. Ensure that care is taken to avoid loss of materials.
- Now remove the steel balls from the sample.
- Nest the 300mm sieves in the required order.
- Sieve the test portion by hand or mechanical shaker.
- Weight all material that passes the 1.70mm sieve.
- Combine and weight all the material that is coarser than 1.70mm and record to the nearest gram.
- The total mass of materials passing and retained on the 1.70mm sieve shall not differ from your initial mass by more than 25g.
- Wash the material coarser than 1.70mm over a 1.70mm sieve until the water runs clear.
- Dry the washed material to a constant mass.
- Once constant mass is achieved the sample should be allowed to cool to room temperature and then re-sieved as in the earlier steps.
- Combine all material retained that is coarser than 1.70mm and weight to the nearest gram.
The Purpose of LA Abrasion Testing
The main principle is ensuring the quality and durability of aggregates used in construction projects. It can help in identifying materials with low durability that may be susceptible to breakdown with impact.
The Importance of LA Abrasion Testing in Construction Projects
It is important to identify early any materials that may by susceptible to a high LA Abrasion value, as this can lead to poor product performance, early deterioration of end products such as new road projects. This in turn can then lead to increased maintenance costs. So, the lower the LA Abrasion value, generally the more durable the material is.
Coffey Testing Can Facilitate LA Abrasion Testing
The following Coffey Testing labs can undertake LA Abrasion Testing:
- Coffey Testing – Perth
- Coffey Testing – Port Hedland
- Coffey Testing – Brisbane
- Coffey Testing – Adelaide
- Coffey Testing – Darwin, and
- Coffey Testing – Newcastle.
LA Abrasion Testing Standards at Coffey Testing
- AS 1141.23
- MR (Qld) Method Q229A & B
- MRWA 220.1 & 220.2
