低浓度氯盐及水灰比对混凝土抗硫酸盐腐蚀性能影响规律的研究

发布时间：2018-11-20 17:17

【摘要】：在海水、滨海地区和西部盐渍土以及工业厂区附近的土壤和地下水环境中，往往同时存在着硫酸盐和氯盐等多种盐类腐蚀性介质。硫酸盐腐蚀是影响混凝土耐久性的重要因素之一，也是对混凝土危害最大、腐蚀机理最复杂的一种环境水腐蚀。本文分析了实际混凝土结构与外界环境之间的关系，针对不同的浸泡状态，考虑水灰比、氯盐浓度、硫酸盐浓度等因素的情况下进行实验室加速腐蚀试验。分别将试件置于纯硫酸盐腐蚀溶液或者不同质量浓度氯盐硫酸盐复合腐蚀溶液中，设定腐蚀龄期，制定研究路线，以基准混凝土作为腐蚀参照组，通过分析受腐蚀混凝土的腐蚀表观现象、X射线荧光分析、力学性能的退化及腐蚀层厚度变化，研究水灰比及氯盐对混凝土抗硫酸盐腐蚀性能的影响规律。通过采用不同的浸泡方式，对全浸泡区和半浸泡区不同水灰比的混凝土试件进行研究，得到不同水灰比混凝土在不同腐蚀区域的抗硫酸盐腐蚀机理；并在基准混凝土的基础上建立修正后的硫酸盐腐蚀速率模型。两种浸泡机制下，较小的水灰比能够起到较好的抗硫酸盐腐蚀的效果；由于半浸泡区存在较严重的物理腐蚀劣化，导致半浸泡区的混凝土抗腐蚀效果比全浸泡区差。采用不同浸泡方式，设定同硫酸盐浓度不同低浓度氯盐的氯盐、硫酸盐复合溶液，研究低浓度氯盐对混凝土硫酸盐腐蚀的抑制作用效果，并建立基于基准模型的复合腐蚀模型。低浓度氯盐的氯盐硫酸盐混合溶液中，氯盐对混凝土硫酸盐的腐蚀效果随着氯盐浓度的增强，并且5%质量浓度氯盐对10%质量浓度硫酸盐抑制效果最好。通过设定基于海洋氯盐浓度的氯盐硫酸盐复合溶液，，研究海洋环境下氯盐对混凝土硫酸盐腐蚀的作用效果，建立对基准腐蚀速率模型引入修正系数后的腐蚀速率模型。海洋氯盐浓度条件下，氯盐浓度相对较高，因而抑制效果较好，但当硫酸盐浓度超过一定值，则抑制效果明显减弱。
[Abstract]:In the environment of seawater, saline soil in coastal area and western region, and in the environment of soil and groundwater near industrial factory area, many kinds of salt corrosive media, such as sulfate and chloride, often exist simultaneously. Sulfate corrosion is one of the most important factors affecting the durability of concrete. It is also a kind of environmental water corrosion which is the most harmful to concrete and the most complex corrosion mechanism. In this paper, the relationship between concrete structure and external environment is analyzed. The accelerated corrosion test in laboratory is carried out under different immersion conditions, such as water-cement ratio, chloride concentration, sulfate concentration and so on. The specimens were placed in pure sulphate corrosion solution or chloride sulfate complex corrosion solution with different mass concentration, the corrosion age was set, the research route was worked out, and the reference concrete was used as the corrosion reference group. By analyzing the corrosion phenomena of corroded concrete, X-ray fluorescence analysis, the degradation of mechanical properties and the change of corrosion layer thickness, the effect of water cement ratio and chloride salt on the corrosion resistance of concrete to sulphate was studied. By using different soaking methods, the different water-cement ratio concrete specimens in the whole immersion zone and semi-immersion zone were studied, and the mechanism of sulfate corrosion resistance of concrete with different water-cement ratio in different corrosion regions was obtained. The modified sulphate corrosion rate model is established on the basis of benchmark concrete. Under two kinds of soaking mechanism, the lower water-cement ratio can play a better effect of resisting sulfate corrosion, and the concrete in semi-immersion area is worse than the whole immersion area because of the serious physical corrosion deterioration in the semi-immersion zone, and the corrosion resistance of the concrete in the semi-soaking area is worse than that in the whole soaking area because of the serious deterioration of physical corrosion in the semi-immersion zone. Different soaking methods were used to set up the chloride and sulfate compound solution with the same sulfate concentration and low concentration chlorine salt. The inhibition effect of low concentration chlorine salt on sulphate corrosion of concrete was studied, and the composite corrosion model based on benchmark model was established. In the mixed solution of chloride sulfate with low concentration of chlorine salt, the corrosion effect of chloride salt to concrete sulfate increases with the concentration of chloride salt, and the best inhibition effect of 5% concentration of chlorine salt on 10% mass concentration of sulfate is obtained. By setting the chloride sulfate complex solution based on the concentration of marine chlorine salt, the effect of chloride salt on sulfate corrosion of concrete in marine environment was studied, and the corrosion rate model after introducing correction coefficient to the benchmark corrosion rate model was established. Under the condition of marine chloride concentration, the concentration of chlorine salt is relatively high, so the inhibition effect is better, but when the sulfate concentration exceeds a certain value, the inhibition effect is obviously weakened.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU528

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