LAUSR

Similar to stiffness, strength or fracture toughness, abrasivity is a characteristic property of rocks. Rock abrasivity has influence on tool wear, energy consumption and construction time and is therefore an important parameter in rock engineering (Atkinson 1993). A number of test methods have been developed to define and quantify the abrasive potential of rocks. Among these, due to simple design and convenient handling, the Cerchar abrasivity test and its index, the Cerchar abrasivity index (CAI), are often used. A detailed description of this test was presented by Cerchar (1986) and published as French standard NF P94-430-1 (2000). Recently, a new paper issued by Alber et al. (2015) provides generalized guidelines for using the Cerchar test method. It has been found that CAI values are affected by various factors, which can be divided into testing condition-based and geological–geotechnical-based ones (Suana and Peters 1982; West 1986, 1989; Al-Ameen and Waller 1994; Alber 2008; Piazzetta et al. 2018; Zhang et al. 2020a, b). For decades, these factors have been studied by many researchers focusing only on the wear of the stylus. Minor attention was paid to investigate the effect on the rock. Recently, Hamzaban et al. (2014) observed the images of scratch grooves on various rocks and discussed the relationship between the applied scratch force on the stylus and its vertical displacement within the rock. The aim of this paper is to investigate a new and comprehensive index for abrasivity and rock cutting efficiency, called Cerchar abrasion ratio (CAR), which considers both parts involved in the interaction (stylus and rock) and which provides an indication of the expected efficiency of cutting or drilling.