Underground excavations in rock are manufactured either by drilling and blasting or by mechanical methods using roadheaders or tunnel boring machines (TBMs). Both methods employ tools which interact with the rock and this interaction leads to the fragmentation of the rock as well as to the wear of the tools. Wear may be defined as the loss of tool material while interacting with the rock. Cerchar abrasiveness test is widely used to assess the abrasiveness of rock to predict of rock cutting tool wear because it provides good information on the abrasiveness with quick and easy testing procedure. Various parameters may affect Cerchar abrasiveness index (CAI), for example, surface condition of rock, mineral contents of rock, etc. In this paper, the relations between geological properties of rock and CAI were examined for several different sandstones. The derivation of some predictive models for the engineering geological properties of sedimentary rocks will be useful due to the fact that the preparation of specimens from the rocks in depth is usually difficult and expensive in preliminary design of underground projects. To develop some predictive models for the CAI from the indirect methods including the quartz content, the cement ,grain content, EQC(Equivalent Quartz Content), Is50 (The size-corrected Point Load Strength Index) , Id2 (Slake Durability Index )and W% (Moisture content),regression analysis were applied on the data pertaining to sandstone rocks from Iran. The grain content was included to the best regression model for the prediction of CAI. It was concluded that the quartz content, the cement content, grain content, EQC, Is50, Id2 and W% are the useful physical and mechanical properties for the prediction of CAI of sandstones.

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