Effects of Wetting-Drying Cycles on the Breakage Characteristics of Slate Rock Grains

It has been found that the physical and mechanical properties of rockfill materials deteriorate when subjected to wetting-drying cycles. Previous studies have mainly focused on the variations of mechanical properties of rockfill materials with wetting-drying cycles. However, the effects of wetting-drying cycles on the breakage characteristics of rock grains still remain unclear. In this study, we perform extensive single grain crushing tests on slate rock grains that have suffered from different wetting-drying cycles. We then investigate the effects of cyclic wetting-drying on the crushing strength, fracture energy, and fragment size distribution of slate rock grains. The results show that both the crushing strength and fracture energy per volume decrease exponentially with increasing wetting-drying cycles, indicating that the deterioration of the mechanical properties of slate grains gradually slows down. The size of fragments follows a fractal distribution, and the fractal dimension shows a linear relationship with the number of wetting-drying cycles, suggesting more small fragments for highly deteriorated rock grains. SEM scanning indicates that the micropores and cracks expand due to wetting-drying cycles. An X-ray diffraction analysis shows that the mineral composition content of slate grains changes after wetting-drying cycles.