硫酸钠溶液环境下混凝土的自愈合性能

发布时间：2018-07-18 10:30

【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。
[Abstract]:By comparing the mechanical properties, crack width, phase composition and microstructure of concrete cracks before and after healing, the self-healing properties of concrete cracks with different concentrations of Na _ 2SO _ 4 solution were studied. The results show that the effect of crack self-healing in solution of% Na _ 2SO _ 4 is obviously better than that in solution of water and solution of Na _ 2SO _ 4, and the recovery rate of strength is 126.5% and the effect of self-healing of crack is most obvious when the effect of crack self-healing is 28 days under the solution of water and solution of Na _ 2SO _ 4, and the recovery rate of strength is 126.5%. The strength recovery rate reached 137.8%, but at 60 days it decreased to 75.8% and the self-healing effect of cracks was in the middle of 75.8% Na _ 2SO _ 4 solution environment. With the increase of Na _ 2SO _ 4 solution concentration, the quantity and volume of ettringite, gypsum and calcium silicate hydrated gel in the crack increase, and the continuous C-S-H gel gradually encapsulates the ettringite which is overlapped with each other and fills the crack to make it self-heal. If the concentration of Na _ 2SO _ 4 solution is too high, the hydration product is enriched and expanded significantly, which leads to the secondary cracking after crack healing.
【作者单位】：天津城建大学材料科学与工程学院;天津市软土特性与工程环境重点实验室;天津市建筑垃圾与燃煤废弃物利用技术工程中心;中铁十八局集团第四工程有限公司;
【基金】：国家自然科学基金资助(51372163)
【分类号】：TU528

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