用铁尾矿粉配制高性能混凝土的研究

发布时间：2018-10-22 18:32

【摘要】：随着我国钢铁工业的不断发展，铁尾矿排放量逐年增大，促进铁尾矿的资源化，无害化利用，提高铁尾矿综合利用率，已经成为一个急需解决的问题。本文以铁尾矿粉为原料，首先研究了用铁尾矿粉作为混合材替代熟料配制水泥的的性能，然后将铁尾矿粉作为填充材料替代部分河砂制备混凝土，并考察混凝土拌合物的工作性能，力学性能和耐久性。采用扫描电镜、压汞仪等的手段表征了铁尾矿混凝土样品的微观形貌和孔径分布。研究结果表明，当颗粒粒径和级配与水泥粉相当的铁尾矿粉作为非活性混合材以0%～20%的比例替代水泥熟料制备水泥时，其物理填充效应并不明显，仅5%掺量以内的水泥强度不降低。水泥强度随着铁尾矿粉掺量的增加而逐渐减小，水泥的流动度下降，凝结时间延长，标准稠度用水量增加，仅安定性检验合格。当复合掺入矿渣粉和尾矿粉时，掺入10%以内铁尾矿粉可以得到与硅酸盐水泥强度相当的水泥。其他物理性能规律与单掺铁尾矿粉的水泥变化规律一致。铁尾矿粉以0%～20%不同比例取代河砂制备混凝土时，对混凝土的拌合物和易性、力学性能、耐久性均产生不同程度的影响。铁尾矿粉掺入后，随着铁尾矿粉掺量的增加，拌合物的和易性下降。为保证混凝土的和易性，，每增加1%的尾矿粉，减水剂用量需增加3.7%，且低标号混凝土的减水剂增加量大于高标号的混凝土。在混凝土和易性相同时，混凝土的抗压强度随铁尾矿粉掺量的增加，先增大后逐渐降低。尾矿粉最佳掺入量随着水灰比的减小而逐渐降低。在水灰比为0.24时，铁尾矿粉掺量为5%混凝土的28d强度达到102.8MPa，相对同龄期的基准混凝土强度增长了26.4%。随着混凝土中铁尾矿粉掺量的增加，混凝土的抗渗性和抗冻性能均有所改善。铁尾矿粉以5%-20%取代河砂后，对混凝土的抗冻性能均有提高，抗冻等级均大于F400；混凝土的抗渗性能也都有所提高，其中尾矿掺量在10%-20%时，提高最明显，混凝土抗渗等级可达到P12。通过扫描电镜和压汞分析发现，铁尾矿粉的加入使混凝土的内部结构更加致密，混凝土填充更加密实，孔径变小，孔隙率降低。
[Abstract]:With the continuous development of iron and steel industry, the iron tailings discharge is increasing year by year. It has become an urgent problem to promote the utilization of iron tailings and improve the comprehensive utilization rate of iron tailings. In this paper, using iron tailings powder as raw material, the properties of cement prepared with iron tailings powder as mixture instead of clinker are studied, and then iron tailings powder is used as filling material to substitute part of river sand to prepare concrete. The working performance, mechanical property and durability of concrete mixture were also investigated. The microstructure and pore size distribution of iron tailings concrete samples were characterized by scanning electron microscope (SEM) and mercury injection apparatus (HG). The results show that the physical filling effect is not obvious when iron tailings with particle size and gradation equal to cement powder are used as inactive mixture to replace cement clinker with 0% or 20% ratio. The strength of cement with only 5% content of cement does not decrease. The strength of cement decreases gradually with the increase of iron tailings powder content, the fluidity of cement decreases, the setting time prolongs, the water consumption of standard consistency increases, and only the stability test is qualified. When the slag powder and the tailings powder are mixed, the cement with the strength of Portland cement can be obtained by adding iron tailings within 10%. Other physical properties are consistent with that of cement with single iron tailings powder. When the iron tailings powder replaces the river sand with 0% 20% different ratio to prepare the concrete, it has different effects on the mixing matter, the easiness, the mechanical property and the durability of the concrete. With the addition of iron tailings powder, the mixing property of iron tailings decreased with the increase of iron tailings powder content. In order to ensure the easiness of concrete, the amount of water reducing agent should be increased by 3.7 for each increase of 1% tailings powder, and the increase of water reducing agent of low grade concrete is larger than that of high grade concrete. With the increase of iron tailings content, the compressive strength of concrete increases firstly and then decreases gradually. The optimum content of tailings decreased with the decrease of water cement ratio. When the water-cement ratio is 0.24, the 28d strength of 5% iron tailings concrete reaches 102.8MPa, and the strength of the concrete of the same age period increases by 26.4MPa. With the increase of iron tailing powder in concrete, the impermeability and freezing resistance of concrete are improved. After replacing river sand with 5% -20% iron tailings powder, the frost resistance of concrete is improved, the frost resistance grade is higher than F400, and the impermeability of concrete is improved, especially when the content of tailings is between 10% and 20%, the concrete impermeability grade can reach P12. The results of scanning electron microscopy and mercury injection analysis show that the iron tailings powder can make the internal structure of concrete more compact, the filling of concrete more dense, the pore size smaller, and the porosity lower.
【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU528

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