Testing of industrial products - Aggregates for construction

The micro-Deval test method

The principle of the method

The test consists of measuring the wear produced by friction between the aggregates and an abrasive charge in a rotating drum in the presence of water. The drums have an internal diameter of 200+/-1mm and are free from protrusions inside.

The test portion consists of two test specimens of mass 500+/-2g. Each test specimen is placed in a separate drum with 2.50+/-0.05L of water and 500+/-5g of steel balls. After 12000+/-10 revolutions at 100+/-5rpm, the percentage of each test specimen that passes a 1.60mm sieve is determined.

The micro-Deval coefficient, MDE, is the average of the two percentages.

The proposed CEN method

The CEN test method has been developed from the French standard P18-572. Some changes have been introduced. Thus, in the CEN method, the micro-Deval coefficient is obtained as the average of the results obtained from two specimens. Also, the preparation of the sample for testing requires the use of either the 11.2 mm or the 12.5 mm sieve, and the aggregate should be dried at 110+/-5C.

Participants in the cross-testing experiment were sent copies of the method that was submitted for CEN Enquiry in 1994.

The micro-Deval test is used in France in parallel with the Los Angeles test (which measures resistance to fragmentation) to determine the mechanical properties of aggregates.