粉煤灰和铁尾矿砂对混凝土抗压强度及微观结构影响试验研究

Experimental study on the influence of fly ash and iron tailings on compressivestrength and microstructure of concrete

本文以粉煤灰及铁尾矿砂掺量为变量进行混凝土抗压强度试验,得到粉煤灰及铁尾矿砂对混凝土抗压强度的影响规律,结合氮吸附法和扫描电镜法等微观分析方法探究粉煤灰及铁尾矿砂对混凝土微观孔隙及形貌结构的作用机理,旨在为工业废弃物粉煤灰和铁尾矿砂在混凝土中的再利用提供理论基础。试验结果表明:混凝土的抗压强度随铁尾矿砂掺量的增加呈现先增强后减弱的变化规律,当铁尾矿砂掺量为30%时,抗压强度达到峰值,此时强度较未掺入时增强5%,增强效果有限;掺入粉煤灰后混凝土的抗压强度得到显著提升,并且随着尾矿砂替代率的提升,粉煤灰的增幅效果逐渐加强,粉煤灰的掺入弥补铁尾矿砂活性不足的缺点。在15%粉煤灰、30%铁尾矿砂掺量时,抗压强度达到最大值,此时强度较普通混凝土增幅12.9%。

In this paper,the content of fly ash and iron tail ore is used as variables to carry out the compressive strength test of concrete,and the influence law of fly ash and iron tail ore on the compressive strength of concrete is obtained.Combined with nitrogen adsorption method and scanning electron microscope method,the mechanism of action of fly ash and iron tail ore on the micro pore and morphology structure of concrete is explored.This paper aims to provide a theoretical basis for the reuse of industrial waste fly ash and iron tail ore in concrete.The test results show that the compressive strength of concrete is firstly enhanced and then weakened with the increase of the iron tail ore content.When the iron tail ore content is 30%,the compressive strength reaches the peak,and the strength is enhanced by 5%compared with that without admixture,and the enhancement effect is limited.The compressive strength of concrete is significantly improved after the incorporation of fly ash,and with the increase of tailings replacement rate,the increase effect of fly ash is gradually strengthened,and the incorporation of fly ash makes up for the shortcomings of insufficient activity of iron tailings.When 15%fly ash and 30%iron tail ore are mixed,the compressive strength reaches the maximum value,and the strength increases by 12.9%compared with ordinary concrete.