石灰石粉对天然轻骨料混凝土力学性能及耐久性影响的研究

发布时间：2018-05-14 16:44

本文选题：天然轻骨料混凝土 + 石灰石粉　；参考：《内蒙古农业大学》2015年硕士论文

【摘要】：天然浮石轻骨料混凝土具有轻质高强、抗震性能优良、抗裂性好、·耐火性好等优势。国内外对轻骨料的研究也日益成熟,在工程上的应用越来越广泛。而随着混凝土掺合料及砂资源的日益紧张,寻找合适的掺合料刻不容缓。石灰石粉作为生产粗骨料和机制砂过程中的废料,如果随意丢弃,既污染环境又浪费资源。因此研究将石灰石粉用作混凝土掺合料可以有效缓解常用掺合料供应不足及价格上涨的现实问题,并降低环境的压力。本文分别将0%,10%,20%,30%,40%,50%的石灰石粉取代等质量的砂子拌制新的轻骨料混凝土,研究不同石灰石粉掺量下轻骨料混凝土在3d,7d,14d,28d,60d,90d,120d时的抗压强度,以及7d,14d,28d,60d的劈裂抗拉强度,将试验结果进行对比,得出石灰石粉的最优掺量为30%,而且石灰石粉有利于提高轻骨料混凝土的后期强度。同时,为进一步研究石灰石粉对轻骨料混凝土内部结构的影响,借助扫描电镜对试件进行微观结构的分析,讨论其破坏机理。另外,为研究石灰石粉对轻骨料混凝土抗冻性的影响,采用快冻法测定在25次,50次,75次,100次,125次,150次,175次,200次,225次,250次循环时的质量损失和动弹模量。然后采用扫描电镜对冻融后的各组试件进行微观机理的分析发现加入过多的石灰石粉对轻骨料混凝土抗冻性十分不利,掺量在30%左右时抗冻性较好。根据超声波探伤原理,测定试件的声时和波速,将每组试验数据建立时-距图。比较计算出的损伤层厚度,发现掺入30%石灰石粉的最优组与基准组损伤层厚度较小,其它组损伤较为严重。
[Abstract]:Natural pumice lightweight aggregate concrete has the advantages of high strength, good seismic performance, good crack resistance and good fire resistance. The research on lightweight aggregate at home and abroad is becoming more and more mature and widely used in engineering. With the increasing strain of concrete admixture and sand resources, it is urgent to find suitable admixture. Limestone powder, as a waste material in the process of producing coarse aggregate and machine-made sand, can pollute the environment and waste resources if it is discarded at will. Therefore, the use of limestone powder as concrete admixture can effectively alleviate the practical problems of shortage of admixture supply and price rise, and reduce the pressure of environment. In this paper, the new lightweight aggregate concrete of the same quality is mixed with 30% limestone powder and 50% limestone powder, respectively. The compressive strength of the lightweight aggregate concrete is studied at 3 d ~ 7 d ~ (14) d ~ (28) ~ 60 d ~ 90 d ~ (-1) ~ 120 d, and the splitting tensile strength of 7 d ~ (14) d ~ (28) ~ 28 d ~ (60) d, and the test results are compared. The optimum content of limestone powder is 30 and the later strength of lightweight aggregate concrete is improved by limestone powder. At the same time, in order to further study the influence of limestone powder on the internal structure of lightweight aggregate concrete, the microstructure of the specimen was analyzed by SEM, and the failure mechanism was discussed. In addition, in order to study the effect of limestone powder on the frost resistance of lightweight aggregate concrete, the mass loss and dynamic modulus of elasticity were measured at 25 times, 50 times, 75 times, 100 times, 125 times, 150 times, 200 times, 225 times, 250 cycles. Then SEM was used to analyze the microcosmic mechanism of each sample after freezing and thawing. It was found that adding too much limestone powder was very disadvantageous to the frost resistance of lightweight aggregate concrete, and the frost resistance of lightweight aggregate concrete was better when the content was about 30%. According to the principle of ultrasonic flaw detection, the sound time and wave velocity of the specimen were measured, and the time-distance map of each group of test data was established. By comparing the thickness of the damage layer, it is found that the thickness of the damage layer in the optimal group with 30% limestone powder is smaller than that in the reference group, and the damage in the other groups is more serious.
【学位授予单位】：内蒙古农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528

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