PHYSICAL-MECHANICAL AND DAMAGE CHARACTERIZATION OF COARSE-GRAINED GRANITE AFTER HIGH TEMPERATURE

This paper carries out the high-temperature test of 25~1200 ℃ for granite from a mine in Yunnan Province and analyzes the rule of change of conventional physical parameters of granite specimens. It analyzes the characteristics of its mineral composition, mineral content, microstructure, physical, and mechanical properties with temperature change by using an X-ray diffractometer, polarizing microscope, and uniaxial compression apparatus. The results show that: (1) the rate of change of mass, volume, density, and wave velocity exhibits significant variation before and after high temperature, mainly due to the detachment of mineral particles, the escape of internal moisture, and the development of microcracks. (2) The mineral composition and microstructure of the granite specimens also changed significantly when the temperature reached 600 ℃, with all minerals except quartz transforming into volcanic glass at 1200 ℃. (3) The temperature has a significant effect on the compressive strength and modulus of elasticity of granite specimens; the higher the temperature, the lower the compressive strength and modulus of elasticity. (4) The ductility characteristics of granite specimens are most evident between 600 ℃ and 1000 ℃, with deformation peaking at 800 ℃, and the compression-density stage being the longest at 1000 ℃.