矿物掺合料对西北盐渍土地区混凝土耐腐蚀性的影响

为解决我国西北盐渍土地区混凝土结构存在的盐蚀问题,掺入矿物掺合料提高混凝土的耐腐蚀性。根据特定工程会对混凝土强度预先提出要求的实际情况,控制混凝土满足C35强度等级,设计单掺、双掺和三掺粉煤灰、矿渣粉及硅灰等6种配合比,采用硫酸盐干湿循环侵蚀、SEM(Scanning Electron Microscope)和XRD(X-Ray Diffraction)等方法研究不同掺合料对混凝土抗硫酸盐侵蚀性能的影响,采用快速氯离子迁移系数和电通量法研究混凝土的抗氯离子渗透性能。结果表明:混凝土强度相同条件下,随着掺合料掺量增加,混凝土抗硫酸盐侵蚀和抗氯离子渗透能力都有提高,且粉煤灰的提高效果高于矿渣粉的提高效果。不同掺合料复掺可以改善混凝土的孔隙结构与水化产物结构,明显提高混凝土的抗硫酸盐侵蚀能力,进一步提高混凝土的耐腐蚀性。

Effect of Mineral Admixture on the Corrosion Resistance of Concrete in Saline Soil Area of Northwest China

Mineral admixtures could enhance the corrosion resistance of concrete to address the salt corrosion of concrete structure in saline soil region of northwest China. In this paper, we examine the influence of admixtures on concrete’s resistance to sulfate corrosion via SEM (Scanning Electron Microscope) and XRD (X-Ray Diffraction) based on the prerequisite that concrete strength is required in advance in specific projects, e.g., at C35 grade. In the test, concrete specimens dosed with single (fly ash or slag powder), double (fly ash and silica fume, or slag powder and silica fume), or triple (fly ash, slag powder, and silica fume) admixtures in different proportions have undergone drying and wetting cycles in sulfate solution. We also investigate concrete’s resistance to chloride ion diffusion using fast chloride ion transfer coefficient and electric flux method. Research findings suggest that at given concrete strength, the climbing of admixture content improves concrete’s ability of resisting sulfate corrosion and chloride ion diffusion. The effect of fly ash is better than that of slag powder. Combining the admixtures could ameliorate concrete’s pore structure and hydration product structure, and boost concrete’s corrosion resistance.