自密实再生混凝土氯离子渗透性能时变规律

为了研究暴露时间对自密实再生骨料混凝土(RA-SCC)抗氯离子渗透性能的影响,并比较其与天然骨料混凝土(NA-C)和自密实天然骨料混凝土(NA-SCC)的抗氯离子渗透性能的差异,将三种混凝土在NaCl溶液中进行浸泡并测定其自由氯离子扩散系数和表面氯离子浓度.结果表明:三种混凝土的氯离子扩散系数随暴露时间的衰减规律符合幂函数变化规律,当混凝土强度等级提高时,RA-SCC表面氯离子扩散系数的时间依赖指数增大,这点与NA-SCC相同而与NA-C相反;三种混凝土的表面氯离子浓度随暴露时间增长规律同样遵循幂函数变化规律,当暴露时间超过60 d时,混凝土表面的氯离子浓度增长不再显著.

Time-dependent law of chlorine ion penetration performance for recycled aggregate self-compacting concrete

In order to study the effect of exposure time on the chloride ion penetration resistance of recycled aggregate self-compacting concrete(RA-SCC), and compare the difference of chloride ion penetration resistance among RA-SCC, natural aggregate concrete(NA-C)and natural aggregate self-compacting concrete(NA-SCC), three kinds of concretes were immersed in NaCl solution, and their free chloride ion diffusion coefficient and surface chloride ion concentration were measured. The results show that the decay law of chloride ion diffusion coefficient with exposure time of three kinds of concretes is in accordance with the variation law of power function. When the concrete strength grade increases, the time-dependent index of chloride ion diffusion coefficient on the surface of RA-SCC increases, which is the same as that of NA-SCC but opposite to the NA-C. The increasing law of surface chloride ion concentration of three kinds of concretes with exposure time also follows the variation law of power function. When the exposure time exceeds 60 days, the chloride ion concentration on the surface of concretes will not increase significantly.