This test method determines the abrasiveness of rock by of measuring the wear on the tip of a steel stylus caused by scratching against a freshly broken or saw cut rock surface for a prescribed 10 mm distance. Basically, the CERCHAR test is a measurement of the relative different hardness of stylus tip and rock specimen surface. Five individual CAI tests shall be conducted for each rock specimen to achieve an average value. CAI is used to assess the abrasiveness of rock for mechanical excavation. Rock abrasiveness governs the performance of disc cutters, the rate of its replacement and therefore subsequent tunnel costs.
3 in of core minimum
Cerchar, abrasivity, index, CAI, rock