盐湖卤水侵蚀喷射混凝土宏观性能及微观结构

Macro performance and microstructure of shotcrete under salt lake brine erosion

通过对普通混凝土、普通喷射混凝土和钢纤维喷射混凝土的质量损失率、相对抗压强度、相对动弹性模量、损伤层厚度、X射线衍射分析(XRD)和扫描电子显微镜(SEM)结果进行分析,研究了(干湿循环+盐湖卤水侵蚀)共同作用下喷射混凝土的宏观性能和微观结构.结果表明:宏观性能方面,质量损失率、相对抗压强度和相对动弹性模量均呈现出先增长后下降的趋势,损伤层厚度为普通混凝土<普通喷射混凝土<钢纤维喷射混凝土;微观结构方面,喷射混凝土中发现的侵蚀产物硅灰石膏,其CO_3^(2-)来源于混凝土内部分含碳酸盐骨料或干燥过程中发生的碳化,由于侵蚀前普通混凝土和普通喷射混凝土存在很多毛细孔,导致其比受钢纤维约束而较为致密的钢纤维喷射混凝土更易遭受盐湖卤水的侵蚀.

The ordinary concrete,ordinary shotcrete and steel fiber shotcrete weight loss ratio,relative compressive strength,relative dynamic elastic modulus,thickness of damaged layer,X-ray diffraction analysis(XRD)and scanning electron microscopy(SEM)results are analyzed to study the shotcrete micro performance and microstructure under the combined action of(salt lake brine erosion and wetting-drying cycles).The results show that in the macro properties,weight loss ratio,relative compressive strength and relative dynamic elastic modulus showed increase first and then decrease trend and the thickness of damaged layer for ordinary concrete< ordinary shotcrete< steel fiber shotcrete;In the microstructure,shotcrete corrosion products of thaumasite were found,and the sources of CO_3^(2-) is derived from the part containing carbonate aggregate or carbonization in the process of drying of concrete,Because ordinary concrete and shotcrete has many pores before erosion,resulting in them more vulnerability to the salt lake brine erosion than steel fiber shotcrete constrained by the steel fiber.