氯离子环境下混凝土裂缝的自愈合行为及对氯离子传输的抑制作用

The Self-healing Behavior of Concrete Cracks Under Chloride Ion Environment and Its Impact on the Inhibitory Effect of Chloride Ion Transport

摘要:

为研究氯离子环境下混凝土裂缝的自愈合行为及其对氯离子传输的抑制作用,模拟了混凝土裂缝动态自愈合过程,分析了不同裂缝宽度和不同浓度氯化钠溶液下混凝土的自愈合效果及其对氯离子传输的抑制机制,探讨了裂缝宽度和氯化钠溶液浓度对裂缝愈合率的影响规律。研究结果显示,宽度为50、150、250 μm的初始裂缝在水中愈合60 d后的愈合率分别为62.1%、24.4%、15.1%,裂缝的愈合率随裂缝宽度的增大而减小。水对裂缝愈合的促进作用有限,在水中仅能有效地愈合尺寸较小的裂缝,裂缝的宽度一般在50 μm以内。500、1 000、2 000 mol/m³ 3种氯离子浓度对不同宽度裂缝自愈合的促进程度不同,当氯离子浓度较低且裂缝尺寸较小时,氯离子对裂缝自愈合有更好的促进作用。在400 mol/m³氯化钠溶液中愈合12 h后,250 μm宽的初始裂缝完全愈合,裂缝周边5 mm处的氯离子平均浓度下降2.6~5.0 mol/m³。

Abstract:

In order to study the self-healing behavior of concrete cracks in a chloride environment and its inhibitory effect on chloride ion transport, the dynamic self-healing process of concrete cracks was simulated. The self-healing behavior of concrete under different crack widths and various sodium chloride solutions was analyzed, as well as the inhibitory effect of crack self-healing on chloride ion transport in concrete. The relationship between crack width and sodium chloride solution concentration on crack healing rate was established. The results show that the healing rates of initial cracks with widths of 50, 150, and 250 μm after 60 days in water were 62.1%, 24.4%, and 15.1%, respectively, with the healing rate decreasing as crack width increased. The promoting effect of water on crack healing was limited, as it only effectively healed smaller cracks, generally with widths within 50 μm. The promotion of self-healing for cracks of different widths varied under chloride concentrations of 500, 1 000, and 2 000 mol/m³. When the chloride concentration was relatively low and the crack size was small, chloride ions exhibited a better promotion effect on crack self-healing. After healing for 12 hours in a 400 mol/m³ sodium chloride solution, the initial cracks with a width of 250 μm were completely healed, and the average chloride ion concentration at 5 mm around the cracks decreased by 2.6~5.0 mol/m³.