尾矿砂PVA水泥基复合材料的制备及耐久性试验研究

发布时间：2018-08-07 13:56

【摘要】：尾矿砂PVA纤维水泥基复合材料,是从节约资源和提高性能两个方面,采用大比例尾矿砂和粉煤灰替代细骨料和水泥,借鉴ECC制备技术,探索研发出的环保型高性能水泥基复合材料。课题组前期已经对这种材料做了大量力学性能试验,研究表明该材料具有良好的力学性能和工程应用前景,但对该材料的耐久性能研究较少。因此,本课题在前期工作的基础上开展了制备技术以及该复合材料的抗冻性、抗渗性能、抗碳化性能、抗硫酸盐腐蚀性能等耐久性能的研究,并且从尾矿砂PVA纤维水泥基复合材料的配合比出发,研究PVA纤维体积率和水胶比对尾矿砂PVA纤维水泥基复合材料抗冻性能、抗渗性能、抗碳化性能和抗硫酸盐腐蚀性能的影响规律,为铁尾矿砂开发和以后水泥基复合材料在工程中的推广应用提供科学依据。论文的主要研究内容及主要结论如下:(1)通过对试验原材料的选取、配合比和搅拌制度的研究,确定了制备该尾矿砂PVA纤维增强水泥基复合材料的原材料、关键材料的合理配合比及其搅拌制度。(2)通过试验室冻融试验,研究了不同冻融循环次数下尾矿砂PVA纤维增强水泥基复合材料的质量损失和抗压强度损失,结果表明:掺加纤维的尾矿砂水泥基复合材料的抗冻性能优于未掺加纤维的尾矿砂PVA纤维增强水泥基复合材料,并且给出了纤维的最优体积掺量;尾矿砂PVA纤维增强水泥基复合材料的抗冻性能随着水胶比的增加逐渐减弱。(3)通过试验室渗水高度试验,研究了尾矿砂PVA纤维增强水泥基复合材料在1.2MPa恒定水压力的作用下材料的抗渗能力,结果表明:掺加一定体积的纤维,可以有效改善尾矿砂水泥基复合材料的抗渗性能,但纤维掺量增加到一定程度时,该材料的抗渗能力反而有所降低;随着水胶比的增加,该材料的抗渗性能逐渐降低。(4)通过试验室快速碳化试验方法,研究了尾矿砂PVA纤维增强水泥基复合材料的抗碳化性能,结果表明:尾矿砂替代率为50%时的尾矿砂PVA纤维增强水泥基复合材料在结构设计使用年限内自然碳化不会到达钢筋表面;掺加一定体积的纤维,能够有效地改善尾矿砂水泥基复合材料的抗碳化性能;随着水胶比的增加,该材料的抗碳化性能逐渐降低。(5)通过硫酸盐干湿循环和湿循环腐蚀试验,对尾矿砂PVA纤维增强水泥基复合材料抗腐蚀性能进行研究,结果表明:干湿循环环境下尾矿砂PVA纤维增强水泥基复合材料比湿循环环境下腐蚀损伤速度快;干湿循环环境下,掺加一定体积的纤维,可以有效改善尾矿砂水泥基复合材料的抗硫酸盐腐蚀性能,并且给出了最优纤维体积掺量;随着水胶比的增加,该材料的抗硫酸盐腐蚀性能逐渐降低。
[Abstract]:The PVA fiber cement matrix composite of tailing sand is used to replace fine aggregate and cement with large proportion of tailings and fly ash from two aspects of saving resources and improving performance, and the preparation technology of ECC is used for reference. To explore the development of environmental-friendly high-performance cement-based composites. A large number of experiments on mechanical properties of this material have been done in the earlier period of the research group. The results show that the material has good mechanical properties and engineering application prospects, but the durability of the material is less studied. Therefore, on the basis of the previous work, the preparation technology and the durability of the composites, such as frost resistance, impermeability, carbonation resistance and sulfate corrosion resistance, were studied. The volume ratio of PVA fiber and the ratio of water to binder are studied from the mixture ratio of PVA fiber cement matrix composites of tailings sand, and the freezing resistance and permeability resistance of PVA fiber cement matrix composites with tailings are studied. The effects of carbonation resistance and sulfate corrosion resistance provide scientific basis for the development of iron tailings and the extension and application of cement matrix composites in engineering. The main research contents and conclusions are as follows: (1) the raw materials for the preparation of PVA fiber reinforced cement matrix composites are determined by the selection of experimental raw materials, mix ratio and mixing system. Reasonable mix ratio of key materials and its mixing system. (2) the mass loss and compressive strength loss of tailings PVA fiber reinforced cement matrix composites under different freezing and thawing cycles were studied through laboratory freeze-thaw test. The results show that the freezing resistance of tailing sand cement-based composite with fiber is better than that of PVA fiber reinforced cement matrix composite without fiber, and the optimum volume addition of fiber is given. The freezing resistance of tailing PVA fiber reinforced cement matrix composites decreases with the increase of water-binder ratio. The impermeability of tailings PVA fiber reinforced cement matrix composites under the constant water pressure of 1.2MPa is studied. The results show that the impermeability of tailings sand cement matrix composites can be improved by adding a certain volume of fibers. However, with the increase of fiber content to a certain extent, the impermeability of the material decreases, and with the increase of water-binder ratio, the impermeability of the material decreases gradually. (4) through the rapid carbonization test method in the laboratory, The carbonation resistance of PVA fiber reinforced cement matrix composites with tailings was studied. The results show that the natural carbonization of PVA fiber reinforced cement matrix composites with a replacement ratio of 50 ore tailings will not reach the surface of reinforcement during the life of structural design. It can effectively improve the carbonation resistance of tailings sand cement matrix composites, and decrease gradually with the increase of water-binder ratio. (5) the corrosion tests of sulphate dry and wet cycle corrosion are carried out. The corrosion resistance of tailings PVA fiber reinforced cement matrix composites is studied. The results show that the corrosion damage rate of tailings PVA fiber reinforced cement matrix composites is faster than that of dry and wet cycling environment. Adding a certain volume fiber can effectively improve the sulfate corrosion resistance of tailings cement matrix composites, and give the optimal volume addition of fiber, and with the increase of water / binder ratio, the corrosion resistance of the composite decreases gradually.
【学位授予单位】：沈阳工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB332

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