弯曲荷载与盐溶液复合作用下混凝土冻融损伤

Freeze-thaw damage of concrete under flexural load and salt solution

依据损伤力学的理论与方法建立了冻融损伤变量,采用超声波法进行混凝土冻融损伤的测试,选取弹簧加载系统对试件施加弯曲荷载,系统试验研究了混凝土在弯曲荷载、硫酸盐、氯盐复合因素作用下的冻融损伤规律和特点.结果表明:弯曲荷载不仅加剧混凝土冻融损伤,而且改变了混凝土的破坏形式,表现出突然的脆性破坏特征;3.5%氯盐溶液、5.0%硫酸盐溶液和3.5%氯盐+ 5.0%硫酸盐复合溶液均减缓混凝土冻融损伤.

A damage parameter of concrete under multiple actions of flexural loading, aggressive agents and freeze-thaw cycles was established based on the damage mechanics. The flexural load on concrete specimen was implemented by a spring loading frame. The ultrasonic technique was employed to investigate the freeze-thaw damage law and properties of concrete under flexural load and salt attack (sulfate and chlorine salt). The experimental results show that the freeze-thaw damage of concrete is accelerated by flexural load and the final fracture of concrete is brittle. On the contrary, the freeze-thaw damage of concrete is decelerated by the sodium chloride solution with concentration of 3. 5% , the sodium sulfate solution with concentration of 5.0% and the compound solution of these salts.