中文摘要：

通过对比混凝土裂缝愈合前后的力学性能、裂缝宽度、物相组成和微观组织,研究了不同浓度Na2SO4溶液环境下混凝土裂缝的自愈合性能。结果表明：Na2SO4溶液环境下裂缝自愈合效果明显优于水。2%Na2SO4溶液环境下裂缝自愈合效果60 d时最明显,强度恢复率达126.5%;6%Na2SO4溶液环境下裂缝自愈合效果28 d时最明显,强度恢复率达137.8%,但在60 d时下降至75.8%;4%Na2SO4溶液环境下裂缝自愈合效果处于两者之间。随着Na2SO4溶液浓度的增大,裂缝中的钙矾石、石膏、水化硅酸钙凝胶等数量增多,体积增大,且连续的C-S-H凝胶逐渐将相互交叉搭接的钙矾石包裹住,填充于裂缝使其自愈合;若Na2SO4溶液浓度过大,水化产物富集且显著膨胀,导致裂缝愈合后二次开裂。

英文摘要：

Concrete self-healing performance at different concentrations of sodium sulfate solution were investigated. The mechanical property, crack width, phase composition and microstructure before and after the repairment of concrete crack were analyzed. The results show that concrete self-healing performance in sodium sulfate solution is much better than that in water. The 2% sodium sulfate solution exhibits the optimum concrete self-healing performance at the curing age of 60 days, when the maximum strength restoration ratio is 126.5%. The 6% sodium sulfate solution has the optimum concrete self-healing performance in the curing age of 28 d, and the strength restoration ratio reduces from the maximum value of 137.8% to 75.8% at the curing age of 60 d. The 4% sodium sulfate solution shows a proper self-healing performance. The amount and size of hydration products, such as ettringite, gypsum and C-S-H gel, increase with the increase of sodium sulfate solution concentration. Ettringite, which is wrapped in C-S-H gel, fills the crack and makes it healed. If the sodium sulfate solution concentration was in an inappropriate range, hydration products would gather and inflate, leading to the second crack.