小麦秸秆—镁水泥复合保温砂浆耐水性能研究

发布时间：2018-07-23 18:07

【摘要】：随着经济和社会的飞速发展,能源消耗量急剧增多,煤炭、天然气等不可再生资源日益短缺,因此国家对建筑提出了节能、低碳、环保的要求。在建筑行业中,建筑能耗大,高耗能建筑比例大,建筑节能状况落后,加快建筑节能建设势在必行。改进墙体的保温隔热性能是建筑节能的重要组成部分,墙体保温隔热材料将是建筑材料发展的新趋势。本文针对小麦秸秆-镁水泥复合保温砂浆在潮湿环境下使用时存在的吸潮返卤、强度损失大等耐水性能方面的缺陷,通过使用四种不同外加剂组成的复合外加剂对小麦秸秆-镁水泥复合保温砂浆进行了耐水性能改性研究,从宏观性能、水化产物稳定性和微观孔结构等角度探讨了复合外加剂对复合保温砂浆强度及耐水性能的影响规律,为其进一步研究提供了理论依据和数据支持。首先,通过阅读相关文献,确定合适的外加剂及其掺量范围,选取小麦秸秆-镁水泥复合保温砂浆的耐水性能评价指标,了解砂浆内部水化硬化机理,学习水泥基材料孔隙结构的相关知识及孔径测试分析方法。其次,选取焦磷酸钠、硫酸亚铁、有机酸、硅灰等四种外加剂组成复合外加剂,并根据四种外加剂的掺量设计正交试验,通过正交试验测试四种外加剂对复合保温砂浆耐水性能的影响顺序并确定四种外加剂的最优掺量。然后,对比分析基准组和最优组试件的宏观性能,通过XRD衍射图谱分析基准组和最优组试件粉末样本的内部水化产物的物相组成,探讨外加剂对复合保温砂浆内部水化产物的影响,通过压汞试验对试样内部微观孔结构进行分析,探讨外加剂对其内部微观孔结构的影响。最后,文中对试验过程中小麦秸秆-镁水泥复合保温砂浆试件表面出现吸潮返卤现象的原因进行了分析,并结合原因提出了改善其抗吸潮返卤性能的措施,以便于减弱其吸潮返卤的弊端,提高其在实际工程应用时的性能表现,有利于其进一步推广应用。经过试验研究得出,复合外加剂的加入,能够显著提高小麦秸秆-镁水泥复合保温砂浆在各龄期的强度,并能有效改善复合保温砂浆的耐水性能,其XRD衍射图谱和压汞试验结果表明,掺入复合外加剂可以提高砂浆5·1·8相的稳定性,可以降低砂浆的总孔隙率,提高密实度,同时可以改变孔径分布,使内部孔结构更加合理,从而提高砂浆的强度和耐水性能。
[Abstract]:With the rapid development of economy and society, the energy consumption is increasing rapidly, and the non-renewable resources such as coal and natural gas are in short supply. Therefore, the country has put forward the requirements of energy saving, low carbon and environmental protection to the construction. In the construction industry, the construction energy consumption is large, the high energy consumption construction proportion is large, the building energy saving condition is backward, it is imperative to speed up the building energy saving construction. Improving the thermal insulation performance of wall is an important part of building energy saving, and wall insulation material will be a new trend in the development of building materials. In this paper, the water resistance defects of wheat straw and magnesium cement composite thermal insulation mortar used in wet environment, such as moisture absorption and halogenation, high strength loss and so on, are pointed out. The water resistance of wheat straw and magnesium cement composite thermal insulation mortar was studied by using four kinds of composite admixtures. The effects of composite admixtures on the strength and water resistance of composite insulating mortar were discussed from the point of view of the stability of hydration products and micropore structure, which provided theoretical basis and data support for its further study. First of all, through reading the relevant literature to determine the appropriate admixture and its range of content, select wheat straw and magnesium cement composite insulation mortar water resistance evaluation index, understand the internal hydration hardening mechanism of mortar. Learn about the pore structure of cement-based materials and pore size measurement and analysis methods. Secondly, four admixtures, sodium pyrophosphate, ferrous sulfate, organic acid and silica fume, are selected to form the composite admixture, and the orthogonal test is designed according to the content of the four admixtures. The influence sequence of four admixtures on the water resistance of composite insulating mortar was tested by orthogonal test and the optimum addition of the four admixtures was determined. Then, the macroscopical properties of the base group and the optimal sample were compared and the phase composition of the internal hydration products of the base group and the optimal group were analyzed by XRD diffraction pattern. The effect of admixture on the internal hydration products of composite insulating mortar was discussed. The micropore structure of the sample was analyzed by mercury injection test, and the influence of admixture on the internal micropore structure was discussed. Finally, the causes of moisture absorption and halogenation on the surface of wheat straw and magnesium cement composite insulation mortar during the test are analyzed, and the measures to improve the resistance to moisture absorption and halogen recovery are put forward. In order to reduce its drawback of moisture absorption and return halogen, improve its performance in practical engineering application, it is beneficial to its further popularization and application. The experimental results show that the strength of wheat straw and magnesium cement composite thermal insulation mortar can be significantly improved with the addition of composite admixture, and the water resistance of composite insulation mortar can be improved effectively. The XRD diffraction pattern and mercury injection test results show that adding compound admixture can improve the stability of 518 phase of mortar, reduce the total porosity of mortar, increase the compactness, change the pore size distribution, and make the internal pore structure more reasonable. Thus, the strength and water resistance of mortar are improved.
【学位授予单位】：山东农业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TU578.1

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