Los Angeles Abrasion Test Procedure

The purpose of this procedure is to determine the abrasion of the given aggregate sample for road works.

For conducting this test you shall need Los Angles Abrasion Machine, Steel balls, Weighing balance and sieves of different sizes i.e. 20, 12.5, 10, 1.7 mm.

Due to the movement of traffic, the road stones used in the surfacing course are subjected to wearing action at the top.

Resistance to wear or hardness is hence an essential property for road aggregates especially when used in wearing course.

Thus road stones should be hard enough to resist the abrasion due to the traffic.

Procedure of Los Angeles Abrasion Test

Take the clean and dried aggregates in an oven at 105-110° C.

Sieve the given aggregates in sieve size 20-12.5mm and weigh that aggregate in 2.5kg.

Again sieve the aggregate in sieve size is 12.5-10mm and take that aggregates in 2.5 k. i.e., W1 gm (2.5+2.5=5kg)

Pour the given taking aggregates into the los angles abrasion machine.

Put the steel balls into the abrasion machine after pouring the aggregates.

Start the machine and rotating the drum for 100 revolutions and stop the machine.

After stopping the machine, take out the aggregates and sieve the aggregates in 1.7mm sieve size and take the retained aggregates and note down its weight i.e., W2 gm.

Then, Los Angles Abrasion value= (W1-W2/W1) x 100 %

Record in Tabular Column

Original weight of aggregate = W1 g
Weight of aggregates retained on 1.7 mm IS sieve  = W2 g
Loss in weight due to wear= (W1-W2) g
Los Angles Abrasion value= (W1-W2/W1)*100 %

 

Result: The Los Angles Abrasion Value of given aggregates is              % at             revolution.

Desirable value of LA Abrasion Test

The Los Angeles abrasion value of good aggregates acceptable for cement concrete, bituminous concrete and other high quality pavement materials should be less than 30%.

Values up to 50% are allowed in base courses like water bound and bituminous macadam.

The maximum allowable Los Angeles abrasion values of aggregates for different methods of road construction are given in below table.

Sl. No.	Types of pavement layer	Los Angeles abrasion value, Maximum %
1	Water bound macadam (WBM), sub-base course	60
2	(i) WBM base course with bituminous surfacing	50
	(ii) Bituminous Macadam base course
	(iii) Built-up spray grout base course
3	(i) WBM surfacing course	40
	(ii) Bituminous Macadam binder course
	(iii) Bituminous penetration Macadam
	(iv) Built-up spray grout binder course
4	(i) Bituminous carpet surface course	35
	(ii) Bituminous surface dressing, single or two coats
	(iii) Bituminous surface dressing, using precoated aggregates
	(iv) Cement concrete surface course
5	(i) Bituminous/Asphaltic concrete surface course	30
	(ii)Cement concrete pavement surface course (as per ISI)