硫酸镁侵蚀环境下石灰石粉—粉煤灰混凝土性能退化机理研究

发布时间：2018-03-01 02:02

本文关键词： 石灰石粉-粉煤灰混凝土硫酸镁侵蚀 SEM XRD　出处：《中国矿业大学》2014年硕士论文　论文类型：学位论文

【摘要】：石灰石粉和粉煤灰作为混凝土的掺合料已经越来越多的出现在工程实践中，但在使用中仍存在力学性能及耐久性能等多方面的问题。硫酸盐侵蚀作为混凝土耐久性研究的重要组成部分，一直倍受关注。本文对复合掺入石灰石粉和粉煤灰的混凝土经受硫酸镁侵蚀后，其性能退化情况进行了分析研究。对石灰石粉-粉煤灰胶砂受硫酸镁侵蚀后，质量变化率、吸水率、抗折强度、抗压强度及抗蚀系数变化规律进行研究。结果表明，粉煤灰单独掺入有利于提高胶砂抗硫酸盐侵蚀性能；石灰石粉、粉煤灰复合掺入，相对用量配制合理情况下所制胶砂具有优良的抗硫酸盐侵蚀性能。石灰石粉-粉煤灰混凝土受硫酸镁侵蚀后，研究其峰值应力、峰值应变、弹性模量及抗蚀系数的变化规律。结果表明，粉煤灰的掺入能改善混凝土抗硫酸盐侵蚀性能，同粉煤灰相比，石灰石粉的单独掺入，，对混凝土抗硫酸盐侵蚀十分不利；石灰石粉与粉煤灰复合掺入形成的混凝土试件具有较高的抗蚀能力；水胶比越小，混凝土抗硫酸盐侵蚀能力越高；与长期浸泡侵蚀环境，浸烘循环加剧了混凝土在硫酸盐中的损伤程度。本文利用XRD技术定量分析长期浸泡和浸烘循环两种侵蚀环境下试件侵蚀产物物相组成演变，并利用SEM分析其微观结构。研究表明，长期浸泡侵蚀120d后，纯水泥净浆的侵蚀产物主要是CaSO4·2H2O。浸烘循环侵蚀方式加剧了试件的侵蚀破坏。
[Abstract]:Limestone powder and fly ash have been more and more used as admixtures of concrete in engineering practice. However, there are still many problems in use, such as mechanical properties and durability. Sulfate erosion is an important part of concrete durability research. The performance degradation of concrete mixed with limestone powder and fly ash after magnesium sulfate erosion has been studied in this paper. The changes of mass change rate, water absorption rate, flexural strength, compressive strength and corrosion resistance coefficient of limestone powder-fly ash cement sand after being eroded by magnesium sulfate are studied. The addition of fly ash alone is beneficial to the improvement of sulfate corrosion resistance of cemented sand, and the composite mixing of limestone powder and fly ash has excellent sulphate resistance when the relative dosage of fly ash is reasonable. The changes of peak stress, peak strain, elastic modulus and corrosion resistance coefficient of limestone powder-fly ash concrete after being eroded by magnesium sulfate are studied. The results show that the addition of fly ash can improve the corrosion resistance of concrete to sulfate. Compared with fly ash, the addition of limestone powder alone is very disadvantageous to the sulphate resistance of concrete, and the concrete specimen mixed with limestone powder and fly ash has higher corrosion resistance, and the smaller the water-binder ratio, the lower the ratio of water to binder. The higher the resistance of concrete to sulfate erosion is, the more severe the damage of concrete in sulphate is due to the immersion cycle in the environment of long-term soaking erosion. In this paper, XRD technique was used to quantitatively analyze the evolution of the phase composition of the corrosion products in two erosive environments, I. e., long-term immersion and drying cycle, and the microstructure of the samples was analyzed by SEM. The results showed that after 120 days of long-term immersion erosion, the microstructure of the samples was analyzed. The erosion product of pure cement slurry is mainly CaSO4 路2H _ 2O.
【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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