杂散电流与硫酸盐耦合作用下混凝土氯离子扩散性能研究

配制了两种配合比的混凝土试件,开展了杂散电流单独作用以及杂散电流与硫酸盐耦合作用下的氯离子侵蚀试验。测试了混凝土中水溶性氯离子含量,计算了不同试验条件下的氯离子扩散系数及其时变规律,分析了杂散电流、硫酸盐以及矿物掺合料对混凝土氯离子扩散性能的影响,并通过微观分析进一步阐述了杂散电流与硫酸盐耦合作用对混凝土氯离子扩散性能的影响机理。试验结果表明:杂散电流会通过电场作用促进氯离子向混凝土内部扩散;复掺粉煤灰和矿粉可降低混凝土孔隙率,显著降低氯离子扩散性能;硫酸盐会与水泥水化产物生成钙矾石,短期内对氯离子扩散起抑制作用,长期将增大氯离子扩散性能;杂散电流与硫酸盐长期耦合作用将增大氯离子扩散性能。

Research in concrete chloride ion diffusion performance under coupling effect of stray current and sulfate salt

Two groups concrete samples with different mix proportion were prepared.A series of chloride ion erosion tests under the separate effect of stray current and the coupling effect of stray current and sulfate salt were carried out.The content of water soluble chloride ion in concrete were tested,and the chloride ion diffusion coefficient and its time-dependent law under different test conditions were calculated.The influence of the stray current,sulfate salt and mineral admixtures on the chloride ion diffusion performance were analyzed.Besides,the influence mechanism about the coupling effect of stray current and sulfate salt was expounded through the microscopic analysis.The results show that the stray current can accelerate chloride ion diffusion to the inner concrete by the effect of electric field.Mixing fly ash and GGBFS can decrease concrete porosity and chloride ion diffusion performance evidently.Sulfate salt can react with hydration products generating ettringite that can inhibit the chloride ion diffusion in short term and enlarge the chloride ion diffusion in long term.The continuously coupling effect of stray current and sulfate salt will enlarge the chloride ion diffusion performance.