Rock abrasivity plays an important role in characterizing a rock material for excavation purposes. Abrasion can be defined as the wearing or tearing away of particles from the surface, i.e. it is a process causing removal or displacement of material at a solid surface, which will lead to wear, especially on tools that are used in mining, drilling, and tunneling applications. The CERCHAR Abrasivity Test is a method to determine an index called CERCHAR Abrasivity Index (CAI) for the rock's abrasivity.The test was originally developed by the Laboratoire du Centre d'E ´ tudes et Recherches des Charbonnages (CER-CHAR) de France for coal mining applications (Cerchar 1986). Two standards exist for this test method: the French standard AFNOR NF P 94-430-1 (2000) and ASTM D7625-10 (2010). The test is widely used in research and practice. There are essentially two designs of testing apparatus: the original design as developed at the CER-CHAR Centre (Valantin 1973) and a modified design as reported by West (1989). While the designs are similar there are some important differences as well as ambiguities in test conditions that include equipment actuation, mate-rial properties of the stylus and sample preparation as summarized by Plinninger et al. (2003). ScopeThe CERCHAR Abrasivity Test is intended as an index test for classifying the abrasivity of a rock material. The test measures the wear on the tip of a steel stylus having a Rockwell Hardness of HRC 55.A rock specimen, disc-shaped or irregular, is firmly held in the test apparatus. The stylus is lowered carefully onto the rock surface. While under a normal force of 70 N, the stylus is moved a total distance of 10.0 mm across the rock.

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Rock abrasivity plays an important role in characterizing a rock material for excavation purposes. Abrasion can be defined as the wearing or tearing away of particles from the surface, i.e. it is a process causing removal or displacement of material at a solid surface, which will lead to wear, especially on tools that are used in mining, drilling, and tunneling applications. The CERCHAR Abrasivity Test is a method to determine an index called CERCHAR Abrasivity Index (CAI) for the rock's abrasivity.The test was originally developed by the Laboratoire du Centre d'E ´ tudes et Recherches des Charbonnages (CER-CHAR) de France for coal mining applications (Cerchar 1986). Two standards exist for this test method: the French standard AFNOR NF P 94-430-1 (2000) and ASTM D7625-10 (2010). The test is widely used in research and practice. There are essentially two designs of testing apparatus: the original design as developed at the CER-CHAR Centre (Valantin 1973) and a modified design as reported by West (1989). While the designs are similar there are some important differences as well as ambiguities in test conditions that include equipment actuation, mate-rial properties of the stylus and sample preparation as summarized by Plinninger et al. (2003). ScopeThe CERCHAR Abrasivity Test is intended as an index test for classifying the abrasivity of a rock material. The test measures the wear on the tip of a steel stylus having a Rockwell Hardness of HRC 55.A rock specimen, disc-shaped or irregular, is firmly held in the test apparatus. The stylus is lowered carefully onto the rock surface. While under a normal force of 70 N, the stylus is moved a total distance of 10.0 mm across the rock.