To determine the abrasion value of coarse aggregate by using Los - Angeles testing machine with an abrasive charge.
Los Angeles Abrasion Machine, Abrasive Charges, Sieve Shaker, Trowel, Weighing Machine.
Select the grading to be used in the test such that it conforms to the grading to be used in construction to the maximum extent possible.
Grading | Weight in gms of each test sample in the size range, mm (Passing and retained on square holes) | Abrasive Charge | ||||||||||
80-63 | 63-40 | 50-40 | 40-25 | 25-20 | 20-12.5 | 12.5-10 | 10-6.3 | 6.3-4.75 | 4.75-2.36 | Number of spheres | Weight of charge, gm | |
A | 1250 | 1250 | 1250 | 1250 | 12 | 5000+/-25 | ||||||
B | 2500 | 2500 | 12 | 4584+/-25 | ||||||||
C | 2500 | 2500 | 8 | 3330+/-20 | ||||||||
D | 5000 | 6 | 2500+/-15 | |||||||||
E | 2500 | 2500 | 2500 | 12 | 5000+/-25 | |||||||
F | 5000 | 5000 | 12 | 5000+/-25 | ||||||||
G | 5000 | 5000 | 12 | 5000+/-25 |
Preferred sample for construction:
Grading : B
Weight of sample in gms: 5000
Number of spheres: 12
Sieve the sample in a 20mm, 12.5mm and 10mm IS sieve.
Collect the sample retained on 10mm and 12.5mm sieve in a separate container and weigh it to 5000g W1(g).
Weight of Grade B sample (W1) = 5000g
Transfer the weighed aggregates and abrasive charge to the circular drum of Los - Angeles machine and fix the cover.
Rotate the machine at a speed of 30 to 33 revolutions per minute. The machine should be balanced and driven such that there is uniform peripheral speed.
Revolution Reading
The entire stone dust is sieved on 1.70 mm IS sieve and is placed in mechanical shaker.
The material coarser than 1.70mm W2(g) size is weighed.
Weight of aggregate retained in 1.70mm sieve (W2)= g
Observation and Results.
Type of work | Abrasion Value |
---|---|
For Wearing surfaces | ≤30% |
For Non Wearing surfaces | ≤50% |
Both ends of the pipe must be trimmed to ensure parallel faces.
Both ends of the pipe must be trimmed to ensure parallel faces.