(B.M.), Built – Up spray grout base course and etc. value of 50%.
For surface course such as WBM, BM, Bituminous Penetration Macadam,Built-Up spray
grout binder course and etc. a value of 40%.
If aggregates are used in surface course as bituminous carpet, bituminous surface
dressing, single or two coats, cement concrete surface course and etc. a value of 35%.
If aggregates are used for bituminous concrete, Cement concrete pavement as surface
coarse than aggregate abrasion value of 30% maximum.
Clean and dry aggregate sample confirming to one of the grading A to G is used for the
test. (Refer table no. 1).
Aggregates weighing 5 kg for grading A, B, C or D and 10 kg for gradings E, F or G may
be taken as test specimen and placed in the cylinder.
The abrasive charge is also chosen in accordance with table no.1 and placed in the
cylinder of the machine, and cover is fixed to make dust tight.
The machine is rotated at a speed of 30 to 33 revolutions per minute.
The machine is rotated for 500 revolutions for gradings A, B, C and D, for gradings E, F
and G, it shall be rotated for 1000 revolutions.
After the desired number of revolutions, the machine is stopped and the material is
discharged from the machine taking care to take out entire stone dust.
Using a sieve of size larger than 1.70 mm I.S sieve, the material is first separated into
two parts and the finer position is taken out and sieved further on a 1.7 mm I.S sieve.
Let the original weight of aggregate be W1 gm, weight of aggregate retained on 1.70 mm
I.S sieve after the test be W2 gm.
Los Angeles abrasion value %= W1-W2 x100
Two tests are done and the average value to the nearest whole number is reported as abrasion value.