中文摘要：

通过分析混凝土裂缝愈合前后的力学性能、裂缝宽度、物相组成和微观结构,研究了不同碱度NaOH溶液（pH值分别为7,9,11和13）环境下混凝土的自愈合性能。结果表明,NaOH溶液对混凝土的自愈合效果优于水;不同碱度NaOH溶液环境下,混凝土的强度、波速均随龄期延长逐渐增大,且增长速率前期较小,中期增大,后期趋于平缓;NaOH溶液的pH值为13时,混凝土的自愈合效果最明显,60d时,强度恢复率约为97.6%,裂缝宽度愈合率约为58.4%;随NaOH溶液碱度的增大,裂缝中C-S-H凝胶、钙矾石等产物逐渐增多,体积增大,连续的C-S-H凝胶将相互交叉搭接的钙矾石骨架包裹住,并在晶体间起胶结作用,使裂缝逐渐愈合。

英文摘要：

Concrete self-healing performance under different alkalinity of sodium hydroxide solution（pH= 7,9, 11,13）were studied by analyzising mechanical property, crack width, phase composition and microstructure be- fore and after the repairment of concrete crack. The results showed that concrete self healing performance under sodium hydroxide solution was much better than water. The strength and ultrasonic velocity of concrete in creased with the increase of pH of sodium hydroxide solution, and the growth rate was slow first,then quick, finally flattened out. When the alkalinity of sodium hydroxide solution was 13, the concretes showed the best self-healing performance, the maximum strength restoration ratio was 97.6% at the curing age of 60 days and the crack width change rate was 43.9%. The amount and size of hydration products, such as ettringite,gypsum and C S-H gel, increased with the increase of sodium hydroxide solution alkalinity. Ettringite was wrapped in C- S-H gel, filled the crack and made it healed.