AASHTO T327

Resistance of Coarse Aggregate to Degradation by Abrasion in the Micro-Deval Apparatus

Applicability: AASHTO T 327 applies to coarse aggregate materials used in asphalt concrete, Portland cement concrete, and unbound base course applications, typically tested using particles in the 9.5 mm to 19.0 mm (3/8 in. to 3/4 in.) size fraction. It is particularly applicable to sedimentary and metamorphic aggregates susceptible to abrasion degradation when wetted, and may be used to supplement or replace the Los Angeles abrasion test in aggregate acceptance testing programs for pavement construction.

Purpose: AASHTO T 327 measures the resistance of coarse aggregate to mechanical degradation by rotating a sample with a charge of steel balls in a water-filled steel drum at a controlled speed for 2 hours, then reporting the percentage of material passing the 1.18 mm (No. 16) sieve as the Micro-Deval abrasion value. Lower values indicate greater resistance to abrasion and higher aggregate durability; results are used to screen aggregate sources for pavement applications, establish specification limits, and evaluate the long-term performance potential of aggregate under traffic loading and freeze-thaw cycling.