ASTM C131/C131M:14 pdf free download – Standard Test Method for Resistance to Degradation of Small-Size Coarse Aggregate by Abrasion and Impact in the Los Angeles Machine.
8. Test Sample Preparation
8.1 Wash the reduced sample (see 9.1.1) and oven dry at 110 ± 5°C [230 ± 9°FJ to a constant mass. separate into individual size fractions, and recombine to the grading of Table 1 most nearly corresponding to the range of sizes in the aggregate as furnished for the work. Record the mass of the sample prior to test to the nearest I g.
9. Procedure
9.1 Place the test sample and the charge in the Los Angeles testing machine and rotate the machine at a speed of 30 to 33 r/min for 500 revolutions (Note 7). After the prescribed number of revolutions, discharge the material from the machine and make a preliminary separation of the sample on a sieve coarser than the 1.70-mm (No. 12) sieve. Sieve the finer portion on a 1.70-mm (No. 12) sieve in a manner conforming to Test Method C136. Wash the material coarser than the 1.70-mm (No. 12) sieve and oven-dry at 110 ± 5°C [230 ± 9°F] to a constant mass, and determine the mass to the nearest I g (Note
Now 7—Valuable information concerning the unifbrmiy of the sample under lest may be obtained by determining the loss after 100evolutions. The loss should be determined by dry sieving the material on the I .70-mm sieve without washing. The rttio of the loss after 1(X) revolutions to the loss after 500 revolutions should not greatly exceed 0.20 for material of uniform hardness. When this determination is made, take care to avoid
losing any part of the sample; return the entire sample, including the dust of fracture, to the testing machine for the final 400 revolutions required to complete the test.
Nom 8—Elimination of washing after lest will seldom reduce the measured loss by more than about 0.2 % of the original sample mass.
9.1.1 If the aggregate is essentially free of adherent coatings and dust, the requirement for washing after the test is optional. However, in the case of referee testing, the washing procedure shall he performed.
10. Calculation
10 1 Calculate the loss (difference between the original mass and the final mass of the test sample) as a percentage of the original mass of the test sample. Report this value as the percent loss (Note 9).
Note 9—The percent loss determined by this test method has no known consistent relationship to the percent loss for the same material when tested by Test Method C535.