Rate Dependence of Splitting Tensile Behaviors of Sandstone and Mudstone

Abstract

The tensile strength measured by Brazilian test is termed the splitting tensile strength. The values of splitting tensile strength and corresponding strain may be affected by loading and/or strain rates used in the Brazilian test. In order to investigate the effects, several Brazilian tests with two-type loading modes were carried out. One is under a constant loading rate (BT-CLR), and the other is under a constant strain rate (BT-CSR). Lightly weathered sandstone and mudstone are selected as test materials. Experimental data indicate that, while the loading rate increases from 0.3 to 0.5 MPa/s, the splitting tensile strengths of sandstone and mudstone are increasing about 12.2% and 16.0%, respectively. With increasing the strain rate from 0.005 to 0.02 mm/s, the splitting tensile strengths of sandstone and mudstone increase about 9.3% and 12.8%, respectively. With increment of loading and/or strain rate, the critical strains of both sandstone and mudstone decrease. The effect degree, in percentage, on the mudstone is greater than one on the sandstone.