No abstract

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.

The abrasiveness of soil and rock is a determining factor for tool wear in all processes of rock excavation above and below ground, for example drilling, cutting and excavating. Although this is highly cost-relevant, no classification scheme has yet been produced, with which soil and rock can be classified according to their abrasiveness and wearing effect. Comparative investigations using three methods of determining abrasiveness were used to produce a proposal for the classification of rock material. Although further series of investigations still have to be performed, a classification scheme has been produced, which is already in practical use and could be of use in future projects.

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.

No abstract