为研究氯盐冻融循环作用下风积沙掺量对混凝土氯离子扩散的影响,试验制备了不同风积沙掺量(质量替代率为0%、25%、50%、75%、100%)的混凝土。通过化学分析法测定盐冻环境下不同风积沙掺量混凝土中自由氯离子浓度和总氯离子浓度,计算了风积沙混凝土相对氯离子结合系数和氯离子扩散系数。结果表明:自由氯离子浓度随风积沙掺量的增大先减小后增大,随冻融循环次数的增加而逐渐增加,风积沙混凝土的结合性能均表现出良好的Langumir非线性吸附,且与冻融循环次数没有直接关系;当风积沙掺量为25%时,相对氯离子结合系数最小,在相同的冻融循环次数下氯离子扩散系数达到最低值;冻融循环作用对大掺量风积沙混凝土氯离子扩散速率的影响较小,风积沙掺量100%的试验组氯离子扩散系数随冻融循环次数的增加而降低,表现出良好的抗氯离子侵蚀能力。由此可见,适量的风积沙掺入能够抵挡氯离子入侵,大量风积沙的掺入提高了混凝土在氯盐侵蚀下的抗冻性能。
Abstract
Concrete specimens with different aeolian sand content (mass substitution rate 0%, 25%, 50%, 75%, 100%) were prepared to conduct experimental research on the effect of aeolian sand content on chloride ion diffusion in concrete under cyclic freezing and thawing of chloride salt. The free chloride ion concentration and total chloride ion concentration in concrete with different aeolian sand contents under salt freezing environment were determined by chemical analysis method, and the relative chloride ion binding coefficient and chloride ion diffusion coefficient of aeolian sand concrete were calculated. Results revealed that the free chloride ion concentration declined at first but then increased with the augment of aeolian sand content, while gradually increased with the proceeding of cyclic freezing and thawing. The binding performance of aeolian sand concrete showed good Langumir nonlinear adsorption and had no direct relationship with freeze-thaw cycles. When the content of aeolian sand was 25%, the relative chloride ion binding coefficient was the smallest. The chloride ion diffusion coefficient hit the lowest value under the same freeze-thaw cycles. Cyclic freezing and thawing had little effect on the diffusion rate of chloride ion in concrete with large content of aeolian sand. The diffusion coefficient of chloride ion of the test group with 100% aeolian sand content decreased with the proceeding of freeze-thaw cycles, displaying good resistance to chloride ion erosion. Proper amount of aeolian sand could better resist chloride ion invasion, and a large amount of aeolian sand could boost the frost resistance of concrete under chloride salt erosion.
关键词
风积沙混凝土 /
盐冻作用 /
氯离子 /
扩散系数 /
冻融循环
Key words
aeolian sand concrete /
salt freezing /
chloride ion /
diffusion coefficient /
cyclic freezing and thawing
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基金
国家自然科学基金项目(51769025);内蒙古自治区自然科学基金项目(2017BS0505);内蒙古科技大学创新基金项目(2019QDL-B48)
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