聚丙烯纤维和石粉对机制砂砂浆基本性能影响的试验研究

发布时间：2019-06-15 21:42

【摘要】：随着我国大规模基础工程设施的建设，天然砂资源日趋紧张、供需矛盾日益尖锐，，机制砂作为混凝土和砂浆的常规原材料而加以利用已成大势所趋。但是，现行《建筑用砂》(GB/T14684-2011)规范严格限制了机制砂中的石粉含量，使得采用除尘或水洗方法生产的机制砂因颗粒多棱角、表面粗糙、自身滚动能力差而大大降低自身流动性，用于配制水泥砂浆容易出现严重泌水、黏聚性差等问题，因此需要研究合理增大机制砂中的石粉含量以改善水泥砂浆的工作性能。同时，采用机制砂配制的水泥砂浆还存在早期干缩大、易开裂等问题，需研究采用聚丙烯纤维对其进行改性。目前，利用聚丙烯纤维改善天然砂水泥砂浆工作性能的研究比较深刻全面，而利用聚丙烯纤维改善机制砂水泥砂浆方面的研究还相对较少。而关于机制砂及所含石粉对水泥砂浆性能的影响研究多集中在单一强度等级下进行，没有考虑水泥用量对石粉掺量的影响，因而得出的结论各不相同。另外，机制砂中石粉含量对水泥砂浆用水量的影响只是定性的进行描述，而缺乏定量分析。基于此本文主要围绕M5、M10、M15、M20四个强度等级水泥砂浆做了以下几个方面的工作： 1)通过试拌寻找机制砂水泥砂浆用水量随石粉含量的变化规律，并提出定量化的计算方法。 2)在保证水泥砂浆工作性能的基础上，研究了机制砂中石粉含量为0、7.9%、10%、15%、20%、25%、30%时水泥砂浆质量密度、抗压、抗折、干缩、抗裂性能的变化规律。 3)在最佳石粉含量的基础上，通过外掺不同长度（6mm、12mm、18mm)和不同掺量（0.6kg/m3、0.8kg/m3、1.0kg/m3、1.2kg/m3）的聚丙烯纤维，研究了聚丙烯纤维掺量和长度对机制砂水泥砂浆抗压、抗折、折压比、干缩、开裂性能的改善效果，提出了利用聚丙烯纤维增强增韧机制砂水泥砂浆性能的关键技术与方法。 4)通过电镜扫描分析机制砂水泥砂浆的SEM图，进行砂浆内部的微观结构和作用机理的试验研究和理论分析。
[Abstract]:With the construction of large-scale infrastructure in China, the natural sand resources are becoming more and more tense, and the contradiction between supply and demand is becoming more and more acute. As the conventional raw materials of concrete and mortar, the utilization of mechanized sand has become the general trend. However, the current Code of Sand for Building (GB/T14684-2011) strictly limits the content of stone powder in the sand, which makes the sand produced by dust removal or washing method greatly reduce its own mobility because of its multi-edge angle, rough surface and poor rolling ability. It is easy to produce cement mortar with serious bleeding and poor cohesion. Therefore, it is necessary to study the reasonable increase of stone powder content in mechanized sand in order to improve the working performance of cement mortar. At the same time, there are still some problems in the cement mortar prepared by mechanical sand, such as early dry shrinkage, easy cracking and so on, so it is necessary to study and modify it with polypropylene fiber. At present, the research on using polypropylene fiber to improve the working performance of natural sand cement mortar is more profound and comprehensive, but the research on using polypropylene fiber to improve the working performance of machine-made sand cement mortar is relatively few. However, the research on the effect of mechanized sand and stone powder on the properties of cement mortar is mainly carried out under a single strength grade, and the influence of cement content on the content of stone powder is not taken into account, so the conclusions are different. In addition, the effect of stone powder content in mechanical sand on the water consumption of cement mortar is only described qualitatively, but there is a lack of quantitative analysis. Based on this, this paper mainly focuses on M5, M10, M15, M20 strength grade cement mortar to do the following aspects of work: 1) through trial mixing to find the change of water consumption of mechanism sand cement mortar with stone powder content, and put forward quantitative calculation method. 2) on the basis of ensuring the working performance of cement mortar, the variation of mass density, compression, bending resistance, dry shrinkage and crack resistance of cement mortar was studied when the content of stone powder in mechanism sand was 0, 7.9%, 10%, 15%, 20%, 25%, 30%. 3) on the basis of the optimum content of stone powder, the improvement effect of polypropylene fiber content and length on the compression, bending resistance, folding ratio, dry shrinkage and cracking properties of machined sand cement mortar was studied by adding polypropylene fiber with different length (6mm, 12mm, 18mm) and different content (0.6kgm3, 0.8kgm3, 1.0kgm3, 1.2kg 路m3), and the effect of the content and length of polypropylene fiber on the compression, bending resistance, folding ratio, dry shrinkage and cracking properties of mechanized sand cement mortar was studied by adding different lengths (6mm, 12mm, 18mm) and different content (0.6kg / m3, 1.0kg / m3, 1.2kg / m3). The key technology and method of using polypropylene fiber to strengthen and toughen the properties of sand cement mortar are put forward. 4) the experimental study and theoretical analysis of the microstructure and action mechanism of the mortar are carried out by scanning electron microscope (SEM) to analyze the SEM diagram of the sand cement mortar.
【学位授予单位】：华北水利水电大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU578.1

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