Effect of water absorption ratio on tensile strength of red sandstone and morphological analysis of fracture surfaces

摘要

Brazilian disc tests were undertaken on a number of red sandstone samples with different water absorption ratios. The tensile strength of the red sandstone decreases as the water absorption ratio increases. The fracture surfaces of failed red sandstone discs were scanned by Talysurf CLI 2000. With the aid of Talymap Gold software, based on ISO25178, a set of statistical parameters was obtained for the fracture surfaces. The maximum peak height (Sp), maximum pit height (Sv) and maximum height (Sz) of the fracture surfaces exhibited the same decreasing trend with increasing water absorption.Sa and Sku values for the fracture surfaces showed a downward trend as the water absorption ratio increased. The fractal dimensions of fracture surfaces were calculated and found to decrease as the water absorption ratio increased. Through analysis of PSD curves, the smallest dominant wavelength was observed to reflect the roughness of the fracture surfaces. Additionally, the results suggest that the roughness of fracture surfaces becomes small as the water absorption ratio increases.