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本文对快速冻融循环与3%氯化钠和5%硫酸钠混合溶液浸泡的交替作用下,混凝土材料性能劣化的机理进行了试验研究;用X射线衍射仪(XRD)与扫描电子显微镜(SEM)分别对试件的水化产物及显微结构进行了测试和分析。结果表明:随冻融循环与混合溶液浸泡次数的增加,混凝土抗压强度明显降低;试件内部出现了微裂缝扩展和裂缝性质的变化,生成了盐类结晶;水泥石组分中也出现了盐类的腐蚀产物(钙矾石和石膏)。可见,冻融循环与盐类混合侵蚀溶液共同作用下,混凝土既出现了物理变化,又发生了化学反应,从而加剧了混凝土力学性能的劣化。
In this paper, the mechanism of deteriorating performance of concrete under the alternating effect of rapid freezing and thawing cycles and immersion in 3% sodium chloride and 5% sodium sulphate was studied. XRD and SEM The hydration products and microstructures of the specimens were tested and analyzed respectively. The results show that compressive strength of concrete decreases with the increase of freeze-thaw cycles and immersion times of mixed solution. Microcrack expansion and fracture properties change in the specimen, resulting in salt crystallization. Salt corrosion products (ettringite and gypsum). Can be seen that the freeze-thaw cycle and salt mixed erosion solution under the joint action of the concrete both physical changes occurred, but also a chemical reaction, thus aggravating the deterioration of mechanical properties of concrete.