Effect of Heat-Treatment on Rock Fragmentation Using Dynamic Ball Compression Test

Rock fragmentation is mainly induced by dynamic mechanical loading in mining and rock engineering. Heat-treatment is one of the rock pre-treatment methods to optimize the rock fragmentation. It is therefore important to investigate the effect of heat-treatment on the outcome of rock fragmentation. This study is concerned with the rock fragmentation in crushing, which is experimentally studied utilizing the dynamic ball compression test conducted by the spilt Hopkinson pressure bar (SHPB) system with a high-speed camera. The spherical specimens made of Laurentian granite (LG) heat-treated under various temperatures (250, 450, 600 and 850 °C) are first characterized by the X-ray micro-computed tomography (CT) method. The damage variable derived from the CT value is used to quantify the thermal damage. The dynamic indirect tensile strength of LG increases with the loading rate under a given heat-treatment temperature. The energy dissipation in crushing is obtained at five fixed input energy levels for all specimens. The energy efficiency (energy dissipation/input energy) of crushing varies with the input energy and the heat-treatment temperature.