The effects of specimen surface conditions and type of test apparatus on Cerchar Abrasivity Index

Abstract

Cerchar abrasivity index test (CAI) is widely used for determining the abrasiveness of rocks. This test provides an index value that can be used as a gauge for the abrasiveness of rocks in order to estimate bit life and wear in various mining and tunneling applications. CAI studies in different laboratories show some variations in their values depending on the test apparatus (classic, west etc) used and tested specimen surface conditions. In this study, the effects of these factors on CAI were investigated. CAI tests were performed with two different test apparatus both on rough and on saw cut specimen surfaces of 13 different rock samples. This study showed that there have been some differences in the values of CAI between rough and saw cut surfaces. It is founded that rough surface CAI values were generally higher than the saw cut surface CAI values. The statistical analysis in this experiment indicates linear relation between CAI values on rough and saw cut surface and CAI values on rough surface is about 15% higher than CAI values on saw cut surface. It has been also found that the type of testing apparatus has insignificant effects on CAI measurements. In this study, CAI measured by Classical test device was higher than CAI measured West apparatus and this difference was about 1%.