AASHTO T 327:12(2020) Standard Method of Test for Resistance of Coarse Aggregate to Degradation by Abrasion in the Micro-Deval Apparatus.
4.1. The Micro-Deval abrasion test is a test of coarse aggregates to determine abrasion loss in the presence of water and an abrasive charge. Many aggregates are more susceptible to abrasion when wet than dry, and the use of water in this test incorporates this reduction in resistance to degradation, in contrast to some other tests that are conducted on dry aggregate. The test results are helpful in evaluating the toughness/abrasion resistance of coarse aggregate subject to abrasion when adequate information is not available from service records.
4.2. The Micro-Deval abrasion test is a useful test for detecting changes in properties of aggregate produced from an aggregate source as part of a quality control or quality assurance process.
5.1. Definition.
5.1.1. constant mass—test sample dried at a temperature of 110 ± 5°C to a condition such that it will not lose more than 0.1 percent moisture after 2 h of drying. Such a condition of dryness can be verified by weighing the sample before and after successive 2-h drying periods. In lieu of such a determination, samples may be considered to have reached constant mass when they have been dried at a temperature of 110 ± 5°C for an equal or longer period than that previously found adequate for producing the desired constant mass condition under equal or heavier loading conditions of the oven.
6.1. Micro-Deval Abrasion Machine—A jar rolling mill capable of running at 100 ± 5 rpm (see Figure 1).
Note I Micro-Deval abrasion machine fitted with a counter may be used if the test is conducted on the basis of number of revolutions (Section 9.4).
Reference Aggregate—An adequate supply of aggregate, established by the laboratory to use for
monitoring testing consistency through the establishment of control limits (see Section 11.1).
The test sample shall be washed and oven-dried at 110 ± 5°C to constant mass, separated into individual size fractions in accordance with T 27, and recombined to meet the grading as shown in Section 8.2.
8.2. Aggregate for the test shall normally consist of material passing the 19.0-mm sieve and retained on the 9.5-mm sieve. An oven-dried sample of 1500 ± 5 g shall be prepared as in Table 1.AASHTO T 327 pdf download.