干湿循环-硫酸盐侵蚀下矿物掺和料对混凝土耐久性的影响

研究了干湿循环-硫酸盐侵蚀耦合作用下,纯水泥混凝土、粉煤灰掺量10%和20%的粉煤灰混凝土及矿粉掺量15%和30%的矿粉混凝土的质量损失率、抗压强度和氯离子扩散系数的演变规律.采用X射线衍射、扫描电子显微镜、能谱分析研究了侵蚀后试件的微观形貌与物质元素组成.结果表明干湿循环-硫酸盐侵蚀耦合作用下混凝土性能发展分为2个阶段:即侵蚀初期性能的提高段与随后性能的劣化段:矿物掺和料的掺入不能改善混凝土的抗干湿循环-硫酸盐侵蚀性能.

EFFECT OF MINERAL ADMIXTURES ON DURABILITY OF CONCRETE IN WETTING-DRYING CYCLIC SULFATE ENVIRONMENT

The effect of mineral admixtures on the cyclic sulfate resistance of concrete was investigated. Concrete specimens with ordinary Portland cement or the cement with fly ash of 10% or 20% or ground blast furnace slag of 15% or 30%, were made and ex-posed to 250 cycles in the cyclic sulfate environment. The specimens properties (such as loss of mass, compressive strength and chlo-ride ion diffusion coefficient) were measured. Microstructure and chemical component of the specimens were determined by X-ray die,action, scanning electron microscopy and energy dispersive spectroscopy. The results show that the performance of concrete sub-jected to cyclic sulfate environment was developed by two stages: improvement stage and deterioration stage. It also indicates that the addition of mineral admixtures in concrete might not improve the cyclic sulfate resistance of concrete.