Deterioration Mechanism of Sulfate Attack on Concrete under Freeze-thaw Cycles
Deterioration Mechanism of Sulfate Attack on Concrete under Freeze-thaw Cycles
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冻融循环下硫酸盐对混凝土的侵蚀劣化机理
DOI：
10.1007/s11595-013-0839-6
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发表时间：
2013-12-01
影响因子：
1.6
通讯作者：
Fei Qiannan
中科院分区：
文献类型：
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作者：
Niu Ditao;Jiang Lei;Fei Qiannan
进行了冻融循环条件下硫酸盐溶液侵蚀混凝土的试验研究。硫酸盐溶液包括5%Na2SO4和5%MgSO4两种类型。通过实验，对冻融循环后的样品进行了扫描电子显微镜、X射线衍射仪和热重分析等微观结构分析。通过热分析对混凝土的腐蚀产物进行了鉴别和定量比较。此外，还研究了耦合作用下考虑混凝土动弹性模量的损伤机理。试验结果表明，在冻融循环和硫酸盐侵蚀的作用下，混凝土中的主要侵蚀产物为钙矾石和石膏。在硫酸镁溶液中的腐蚀产物多于在Na2SO4溶液中的腐蚀产物。此外，混凝土中石膏的含量低于钙矾石，只有在一定的腐蚀程度后才能观察到部分石膏的存在。试验还表明，在冻融循环下，硫酸镁溶液对混凝土的损伤有促进作用。而对于Na2SO4溶液，在300次冻融循环前，混凝土的损伤已经得到抑制，但在进一步的试验阶段，硫酸盐侵蚀加速了混凝土的劣化过程。
The experiments of concrete attacked by sulfate solution under freeze-thaw cycles were investigated. The sulfate solution includes two types of 5% Na2SO4 and 5% MgSO4. Through the experiment, microstructural analyses such as SEM, XRD and TGA measurements were performed on the selected samples after freeze-thaw cycles. The corrosion products of the concrete were distinguished and quantitatively compared by the thermal analysis. Besides, the damage mechanism considering the dynamic modulus of elastically of concrete under the coupling effect was also investigated. The experimental results show that, under the action of freeze-thaw cycles and sulfate attack, the main attack products in concrete are ettringite and gypsum. The corrosion products exposed to MgSO4 solution are more than those to Na2SO4 solution. Furthermore, the content of gypsum in concrete is less than that of ettringite in test, and some of gypsum can be observed only after a certain corrosion extent. It is also shown that MgSO4 solution has a promoting effect to the damage of concrete under freeze-thaw cycles. Whereas for Na2SO4 solution, the damage of concrete has restrained before 300 freeze-thaw cycles, but the sulfate attack accelerates the deterioration process in its further test period.