An investigation of thermal effects on micro-properties of granite by X-ray CT technique

The thermal effects on micro-properties of granite were experimentally studied. The volumetric porosity was observed by the X-ray Computed Tomography (CT) technique and three-dimensional (3D) image reconstruction. Two indexes (heterogeneity coefficient and anisotropy coefficient) were proposed to describe the micro-properties of granite. The thermal effects on these two indexes were discussed. The results shows that micro-porosity increases as temperature increases between 400 degrees C and 800 degrees C. It is slightly influenced by temperature beyond this range. Both of the heterogeneity and anisotropy of thermal treated granite increase to their maximums as temperature increases to 500 degrees C, than decrease to constants as temperature further increases. The heterogeneity and anisotropy of granite are mainly dominated by the initial cracks below 200 degrees C. The thermal induced cracks are mainly in the regions of lower density mineral grains below 400 degrees C. Boundary cracks and trans-granular cracks generate significantly above 500 degrees C.