Los Angeles Abrasion Tester

Overview:

The L A abrasion machine is used to measure the degradation of mineral aggregate of standard gradings resulting from a combination of actions including abrasion or attrition, impact and grinding in a rotating steel drum containing a specified number of steel spheres. The test is widely used as an indicator of the relative quality of various sources of aggregate having similar mineral compositions.

The standard L.A. abrasion test subjects a coarse aggregate sample (retained on the No. 12 (1.70 mm) sieve) to abrasion, impact, and grinding in a rotating steel drum containing a specified number of steel spheres.

After being subjected to the rotating drum, the weight of aggregate that is retained on a No. 12 (1.70 mm) sieve is subtracted from the original weight to obtain a percentage of the total aggregate weight that has broken down and passed through the No. 12 (1.70 mm) sieve. Therefore, an L.A. abrasion loss value of 40 indicates that 40% of the original sample passed through the No. 12 (1.70 mm) sieve.

Background:

Aggregates undergo substantial wear and tear throughout their life. In general, they should be hard and tough enough to resist crushing, degradation and disintegration from any associated activities including manufacturing, stockpiling, production, placing and compaction

(Roberts et al., 1996[1]). Furthermore, they must be able to adequately transmit loads from the pavement surface to the underlying layers and eventually the subgrade. These properties are especially critical for open or gap graded, which do not benefit from the cushioning effect of the fine aggregate and where coarse particles are subjected to high contact stresses (Wu et al., 1998[2]). Aggregates not adequately resistant to abrasion and polishing may cause premature structural failure and/or a loss of skid resistance. Furthermore, poor resistance to abrasion can produce excessive dust during production resulting in possible environmental problems as well as mixture control problems.

Alkalmazandó szabványok:

JTG 3432-2024 "Aggregate Test Regulations for Highway Engineering" : The T0317-2005 Los Angeles method for coarse aggregate wear test in this standard specifies the specific requirements, test methods and data processing of the Los Angeles wear tester.

standards:

ASTM C535

AASHTO T96

ASTM C131/131M

AASHTO T 401

Main parameters:

Cylinder:

Inner diameter: 711mm±5mm

Length: 508mm±5mm

Wall thickness: 12.0mm±0.5mm

Feeding port （cylinder surface） width: 150mm±3mm

Cover width （may vary by model） : 190mm, etc

Bulkhead （may be equipped, depending on model） : Protrusion size, thickness, distance from edge, etc. are specified

Speed: The cylinder's speed is usually between 30r/min and 33r/min.

Counter: The number of counter bits is usually 4 or 5 bits, which can be automatically digital display and preset rotation times. Some models have a maximum set value of 9999 times or more.

Steel Ball:

Diameter: between 45.6mm and 47.6mm, the exact diameter may vary slightly depending on the test requirements.

Mass: The mass of a single steel ball is between 390g and 445g. The size and mass of a set of steel balls may vary slightly, but the average diameter and average mass must meet the specified requirements. The average diameter is 46.8mm and the average mass is about 420g.

Quantity: The number of steel balls in a set is usually 12, 15, or other specified quantity.

Working power supply: AC380V 50Hz AC power is usually used, and the power is about 1.5Kw.

Overall dimensions and weight:

Dimensions: May vary by model, such as 850mm×1100mm×1550mm, etc.

Weight: May vary by model and material, e.g. 320kg or so.