氯盐干湿循环作用下混凝土力学性能与孔结构变化研究

Study on concretemechanical performance and pore structure change under effect of chlorine salt dry-wet cycle

为探究淡水区和氯盐环境下干湿循环对混凝土构件的影响差异,分别模拟了无氯盐和有氯盐作用的干湿循环环境,测试干湿循环前后混凝土的抗压强度、动弹模量、微观孔结构参数及孔径分布情况,比较了宏微观指标变化程度。结果表明,两种干湿循环作用均对混凝土抗压强度有少许增强作用,微观表现为孔隙率的减小;两种干湿循环均会降低混凝土的动弹模量,使混凝土内部出现损伤,微观表现为混凝土孔径分布情况变差,特别是大孔含量有增加。一般干湿循环会使混凝土抗渗性增强,氯盐干湿循环会降低混凝土抗渗性,微观表现为一般干湿循环后混凝土临界孔径减小,而氯盐干湿循环后,混凝土临界孔径增大。

In order to explore the difference between the influences from dry-wet cycle on concrete members under the chloride-salt environment and in freshwater region,the dry-wet cycle environments without and with chloride-salt effect are simulated respectively,and then the compressive strengths,the dynamic-elastic moduli,the microscopic pore structure parameters and pore size distributions of concrete before and after dry-wet cycle are tested,while the changes of both the macro and micro indicators are compared as well.The study result shows that both the effects of dry-wet cycle play a little enhancing role on the compressive strength of concrete,for which the microscopic representation is the decrease of porosity.Both the dry-wet cycles can lower the dynamic-elastic modulus and make damage occur inside concrete,for which the microscopic representation is that the pore size distribution become worse,especially the macropore content is increased.The common dry wet cycle can increase the anti-permeability of concrete,but the chlorine salt dry-wet cycle can lower the anti-permeability of concrete with the microscopic representation of the decrease of the critical pore size after common dry wet cycle,while the critical pore size of concrete is to be increased after chlorine salt dry-wet cycle.