THE INFLUENCE OF CATACLASIS ON ABRASION RESISTANCE OF GRANITIC-ROCKS USED AS ROAD SURFACE AGGREGATES

The research described in this paper is performed on cataclastic rocks of granitic composition. The petrography is described and classified according to Higgens. All rocks appear with primary cohesion and range from cataclasite to mylonite gneiss. A crystallinity index for quartz minerals based on the degree of resolution of the d, X-ray reflection at 1.3820 angstrom is examined. It is found that the crystallinity in dex corresponds fairly well with the degree of distruction/annealing i n cataclastic rocks. It is concluded that the index can be used as a q uantitative measure of the state of ductile deformation in cataclastic rocks. However, an attempt to explain the relationship between the ab rasion value, i.e., the hardness of the rocks, and the crystallinity i ndex as a simple linear association, failed. It is believed that this at least partly is due to the grain size distribution in the rocks whi ch has a stronger impact upon the strength properties than the ductile deformation, causing scatter in the regression model.