LOS ANGELES ABRASION
Along with the rapid growth in development, including in the field of infrastructure, aggregate is one of the materials that has a quite important role in it. In general, aggregates are distinguished by their size, there are coarse aggregate and fine aggregate. According to SNI 03-2847-2002, fine aggregate is an aggregate that has a maximum grain size of 5.00 mm and coarse aggregate has a grain size between 5.00 mm and 40 mm. Several other sources state that coarse aggregate is aggregate with a size of more than 4.75 mm, while fine aggregate is less than 4.75 mm.
The important role of this aggregate, among the other things, is as a concrete mixture material for both road works, bridges, high-rise buildings and various other types of infrastructures as well as for various other types of mixtures. To get a high quality infrastructure, the aggregate quality also needs to meet the requirements according to a certain infrastructure.
Aggregate itself can undergo various processes such as splitting, erosion due to weathering, erosion during mixing and/or due to spreading, due to compaction and so on. Therefore, to determine the quality of an aggregate, it is necessary to carry out various series of tests according to the needs/goals of the customers. One of the aggregate tests that is often an important part in various development purposes is abrasion test on aggregate using a Los Angeles abrasion machine.
For example in the construction of road works, the use of aggregate that does not meet the abrasion requirements can result in disruption of the stability of the pavement construction and asphalt adhesion against aggregates. Even after the road is in operation, the aggregate is still undergoing an abrasion process, for example by the wheels of vehicles. So the abrasion test on aggregate using a Los Angeles abrasion machine is very important thing to do.
This test is a measure of degradation of mineral aggregates 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 number depending upon the grading of the test sample. As the drum rotates, a shelf plate picks up the sample and the steel spheres, carrying them around until they are dropped to the opposite side of the drum, creating an impact crushing effect. The contents then roll within the drum with an abrading and grinding action until the shelf plate picks up the sample and the steel spheres, and the cycle is repeated. After the prescribed number of revolutions, the contents are removed from the drum and the aggregate portion is sieved to measure the degradation as percent loss. (ASTM C 131)
