Modification of Schimazek Abrasivity Index for Improving its Application in Rock Engineering

up to now, various indexes and methods have been presented for evaluating the abrasivity of rocks. in total, these methods can be divided to two main groups; the methods based on nature of rocks, methods based on heuristic tools. Schimazek index is one of the most powerful and applicable methods for evaluating the rock abrasiveness. This index uses the grain size, Brazilian tensile strength and equivalent quartz content for abrasivity analysis. Since the values of these parameters are equal in Schimazek index, therefore, in some cases this index doesnt have suitable ability for distinguish. In this research, has been attempted to consider the weight of each parameter in rock abrasivity using Fuzzy Delphi Analytical Hierarchy Process (FDAHP) and to modify the Schimazek index according to this weights. In next stage, in order to verification of new index, ten ornamental rocks have been studied and the old and modified indexes were calculated. Then, the cutting rate of each stone has been recorded and the mathematical relationships between new and old indexes have been achieved. The results show that the new Schimazek abrasivity index has higher ability than old one.