A proposed weathering classification for basalts and their engineering properties (Turkey)

Most of the volcanic rocks widespread in Turkey are basalt. The effect of weathering processes on the physical and mechanical properties of this type of rock is important. To assess these properties and relations to each other, a study was undertaken in the Niksar region. A detailed investigation was carried out on basalts in the road cuttings of the Niksar ring road and Ünye-Akku?-Niksar highway alignments. A new classification system for basaltic rocks which are substantially influenced by weathering is proposed. The basic engineering properties of the basalt representing each weathering grade were determined. The properties tested are dry density, porosity, coefficient of permeability, uniaxial compressive strength, tensile strength and Young’s modulus. Interrelationships were determined for all test results. It is concluded that there is a substantial degradation in the engineering properties of the rock beyond a specific degree of weathering.