复杂环境下粉煤灰水泥石的离子浓度分布与维氏硬度劣化规律

摘要/Abstract

摘要： 地铁工程混凝土结构处于硫酸盐、氯盐及杂散电流共存的复杂环境。本文针对地铁工程环境下混凝土的耐久性问题,研究了硫酸盐、氯盐及电场共同作用下,粉煤灰掺量对水泥石内硫酸根离子浓度分布、氯离子浓度分布和维氏硬度分布的影响,并基于Logistic函数建立维氏硬度预测模型,最后采用XRD分析了水泥石劣化的机理。结果表明:随侵蚀深度的增加,水泥石内硫酸根离子浓度不断降低,氯离子浓度呈现先增后降的趋势;侵入水泥石的氯离子和硫酸根离子的含量都随粉煤灰掺量的增加而先减后增,当粉煤灰掺量为10%(质量分数)时,侵入水泥石的氯离子与硫酸根离子的含量最低;被侵蚀后的水泥石内维氏硬度分布分为劣化区、增强区和完好区三个区域;预测模型可以准确表征水泥石内维氏硬度分布规律;适量粉煤灰的掺入可以减少受侵蚀后试件内的钙矾石(AFt)和石膏含量。

关键词: 粉煤灰, 水泥石, 硫酸根离子, 氯离子, 维氏硬度, 预测模型

Abstract: Reinforced concrete structures in subway engineering are often exposed to a combination of sulfate, chloride and stray current. In this study, the effect of the amount of fly ash on the distribution of sulfate ion concentration distribution, chloride ion concentration distribution and Vickers hardness of cement pastes under the coupling effect of sulfate, chloride and electric field were discussed. Moreover, the logistic function was applied to the prediction model of Vickers hardness. Finally, mechanism and deterioration of cement pastes were analyzed by XRD. The results show that as the erosion depth increases, the concentration of sulfate ion decreases continuously, while chloride ion concentration increases first and then declines gradually. With the increase of fly ash addition, the chloride ion and sulfate ion invading cement pastes decrease first and then increase. When the fly ash content increases to 10% (mass fraction), the content of chloride ion and sulfate ion invading specimen is the lowest. The Vickers hardness distribution of the eroded cement pastes is divided into three areas: degraded area, enhanced area and intact area. There is a good correlation between the prediction model and the experimental values of Vickers hardness. A suitable content of fly ash addition reduces the formation of ettringite and gypsum in the eroded cement pastes, and improves the stability of bound chloride ion.

Key words: fly ash, cement paste, sulfate ion, chloride ion, Vickers hardness, prediction model

中图分类号:

TU528.01

王涛, 储洪强, 丁天云, 朱正宇, 曾有旭, 谢嘉璇, 蒋林华. 复杂环境下粉煤灰水泥石的离子浓度分布与维氏硬度劣化规律[J]. 硅酸盐通报, 2021, 40(12): 4011-4019.

WANG Tao, CHU Hongqiang, DING Tianyun, ZHU Zhengyu, ZENG Youxu, XIE Jiaxuan, JIANG Linhua. Ion Concentration Distribution and Vickers Hardness Degradation of Fly Ash Cement Pastes in Complicated Environment[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2021, 40(12): 4011-4019.

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