ABSTRACT
Changing one property at a time is necessary if data are to be obtained for evaluating the effects of each property on the total wear process. Since natural rock types cannot meet this requirement, artificial rock types were used to determine the effects of changing one property at a time. Mortar types of different compositions seemed to be suitable. Also natural rock types have been tested to compare the expected rate and type of wear with the results of experiments on the mortars. Five types of sandstone and two types of limestone have been used. The natural rock types were superficially homogeneous and isotropic in the test specimen and were expected to be suitable to carry out a number of experiments with a high repeatability. The ratio of compressive strength and tensile strength may indicate a brittle or ductile behaviour of the rock; a low ratio indicating ductile and a high ratio indicating brittle behaviour.
