Paper Title
Correlation between CERCHAR Abrasivity Index of Smooth and Rough Rock Fractures

Abstract
The objective of this study is to determine the correlation of CERCHAR abrasivity index (CAI) between smooth (CAIs) and rough (CAIr) fractures. Uniaxial compressive strength and equivalent quartz content are also correlated with CAI. Nineteen types of rock specimens commonly found in the north and northeast of Thailand are prepared to obtain saw-cut surfaces and tension-induced fractures. They are classified into five groups: clastic, plutonic, carbonate, sulfate and chloride, and volcanic groups. Results indicate that CAI values of rough surface is slightly higher than those of smooth surface. Good linear correlation is obtained as indicated the coefficient of correlation (R2) is greater than 0.9. Both abrasivity indexes obtained from rough and smooth surfaces correlate fairly well with the rock compressive strength (R2> 0.7). CAIs shows slightly better correlation with the strength than CAIr does. Correlation between CAI values and equivalent quartz content is relatively poor. This may be due to the fact that relatively narrow range of rock characteristics have been used in the test. Keywords - Abrasivity, Equivalent Quartz Content, Rock Strength, Fractures