For determination of resistance to wear of coarse aggregate by abrasion. A rolled steel drum totally closed except for removable dust-tight cover is connected to stub shaft and mounted on steel frame to allow rotation about its axis in a horizontal plane. The drum is rotated by one h.p. electric motor. A heavy duty speed reducer coverts the motor speed to required drum speed of 30 to 33 r.p.m. Inside the drum is provided a steel shelf which can be easily replaced when worm out due to repeated abrasion tests. Supplied with 12 abrasive charges 1 7/8" dia and Revolution Counter fitted to the rotating shaft.