石粉特性对混凝土性能的影响研究

发布时间：2018-08-27 13:09

【摘要】：由于天然砂资源短缺、质量下降、价格上涨，建筑用砂需求量不断增大，使得机制砂混凝土在工业与民用建筑工程、水利水电工程和道路桥梁等工程中的应用研究越来越广泛。然而，石粉对混凝土性能的影响的研究主要集中在石粉含量方面，而常常忽略了石粉特性之间的差异，石粉特性方面的研究较少且不够系统。因此研究机制砂中石粉特性对机制砂混凝土性能的影响具有一定的理论意义和重要的实用价值。通过对不同地区的机制砂样及石粉特性的检测与统计分析，发现不同地区生产的机制砂的粒形、级配、泥块含量、石粉特性及含量存在较大差异，并为此探讨了机制砂含泥量的表征方法及限值。研究认为，机制砂干筛石粉的MB值与石粉含量的组合并不能很好地反映机制砂中含泥情况，而机制砂MB值与2.36mm通过率、水筛石粉MB值与石粉含量能更好的反映机制砂中含泥量。研究了纯石粉岩性、细度以及泥粉种类及掺量对石粉MB值的影响，研究发现对于纯石粉，细度的增加对MB值影响不大；不同岩性的纯石粉的MB值有较大的差异，这与石粉的矿物成分和结构有关；石粉的MB值随泥粉掺量的增大而线性递增，其斜率与泥粉的泥质有关；相比细度和岩性而言，含泥量对石粉MB值的影响最为显著。研究了不同细度、岩性及MB值的石粉以10%的比例替代机制砂时对砂浆和C30、C60混凝土的工作性、强度、耐久性能以及体积稳定性的影响。研究发现，石粉细度和岩性对低强和高强混凝土性能的影响有不同的规律，但总体而言，，细度对混凝土性能的影响较小，不同岩性石粉对混凝土性能的影响有较大的差异，MB值对混凝土性能的影响十分显著，特别是工作性、抗冻性和体积稳定性。对于含有10%石粉的机制砂混凝土，C30混凝土对应石粉的MB值不宜超过14，对于C60混凝土，石粉MB值不宜超过10。对于大流态混凝土或抗冻性要求较高的混凝土，石粉中含泥量的控制应更严格。当集料中含泥量较高时，加入一定量的能优先吸附在泥粉上的添加剂（如亚甲蓝），能够改善混凝土工作性，提高减水剂的减水效果和适应性，同时对混凝土的强度和耐久性等影响较小，甚至有所提高。
[Abstract]:Due to the shortage of natural sand resources, the decline of quality, the rising price and the increasing demand for building sand, the application of machine-made sand concrete in industrial and civil construction projects, water conservancy and hydropower projects and road and bridge projects is becoming more and more extensive. However, the effect of stone powder on concrete performance is mainly focused on the content of stone powder, and the difference between stone powder properties is often ignored. The research on stone powder characteristics is less and less systematic. Therefore, it has certain theoretical significance and important practical value to study the influence of stone powder characteristics in machine-made sand on the properties of machine-made sand concrete. Through the detection and statistical analysis of the characteristics of machine-made sand and stone powder in different areas, it is found that there are great differences in grain shape, gradation, mudblock content, stone powder characteristic and content of machine-made sand produced in different areas. Therefore, the characterization method and limit value of the mud-content of machine-made sand are discussed. The results show that the combination of MB value and stone powder content of the dry sieve stone powder can not well reflect the mud content in the mechanism sand, but the MB value and the 2.36mm pass rate of the machined sand, the MB value and the content of stone powder of the water sieve powder can better reflect the mud content in the machine-made sand. The effects of lithology, fineness, type and content of mud powder on the MB value of stone powder are studied. It is found that the increase of fineness has little effect on the MB value of pure stone powder, and the MB value of pure stone powder with different lithology has great difference. This is related to the mineral composition and structure of stone powder, the MB value of stone powder increases linearly with the increase of the content of mud powder, and its slope is related to the mud quality of mud powder. Compared with fineness and lithology, the influence of mud content on MB value of stone powder is the most significant. The effects of different fineness, lithology and MB value of stone powder on workability, strength, durability and volume stability of mortar and C30C60 concrete were studied. It is found that the influence of stone powder fineness and lithology on the performance of low strength and high strength concrete is different, but in general, the influence of fineness on the performance of concrete is small. The effect of rock powder on concrete performance is quite different. The effect of MB value on concrete performance is very significant, especially the workability, frost resistance and volume stability. The MB value of the concrete containing 10% stone powder should not exceed 14, and the MB value of stone powder should not exceed 10% for the C60 concrete. For large flow concrete or concrete with high frost resistance, the control of mud content in stone powder should be more strict. When the amount of mud in the aggregate is high, adding a certain amount of additives (such as methylene blue) which can preferentially adsorb on the mud powder can improve the workability of concrete and improve the water reducing effect and adaptability of the water-reducing agent. At the same time, the strength and durability of concrete are slightly affected, even improved.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU528

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