Abstract：Based on the direct shear tests and microscopic scanning on concrete specimens exposed to sulfate attack of different periods, the influencing mechanism of sulfate attack on the shear strength and failure mode of concrete under partial-immersion condition was analyzed, and then compared to that under full-immersion condition. Results show that sulfate attack can result in the time-dependent degeneration of concrete shear strength; with the exposure duration, both the adhesion component(represented by cohesion)and shear dilation component(represented by shear dilation rate)of concrete shear strength exhibit the gradual reduction tendency, but the decreasing amplitudes under partial-immersion condition are smaller than those under full-immersion condition, and the residual shear dilation rates of concrete specimens with three different water-to-binder ratios under partial-immersion condition are 0.237(0.38), 0.206(0.45)and 0.182(0.52), respectively; friction component(represented by internal friction angle)exhibits a trend of non-linear reduction under partial immersion condition, without exhibiting earlier-stage distinct enhancement(2%～6% enhan-cement)under full-immersion condition, and after partial immersion of 9 months the decreasing amplitudes of internal friction angle of concrete specimens with three different water-to-binder ratios are 24.9%(0.38), 32.8%(0.45)and 52.3%(0.52), respectively. Microanalysis indicates that this phenomenon is closely related to the microscopic erosion mechanism, and under partial immersion condition the damage of specimen is dominated by physical salt crystallization, which is different from that under full-immersion condition; different erosion mechanisms may lead to significant differences in failure mode on shear plane of concrete during shearing; under full-immersion condition, the failure modes of shear plane mainly appear to be the rolling and stripping of aggregates as well as the extrusion and slippage of matrix near shear plane, however, they shall be dominated by matrix cracking and shear dilation slippage under partial-immersion condition.
张中亚 周建庭 邹杨 杨俊 靳晓光. 硫酸盐侵蚀对混凝土抗剪性能的影响[J]. 土木工程学报, 2020, 53(7): 64-72.
Zhang Zhongya Zhou Jianting Zou Yang Yang Jun Jin Xiaoguang. Effect of sulfate attack on the shear performance of concrete. 土木工程学报, 2020, 53(7): 64-72.
