铁尾矿-磷渣-脱硫灰三元固废混凝土抗压性能研究

Study on Compressive Strength of Concrete in Iron Tailings-Phosphate Slag-Desulfurization Ash Ternary Solid Waste System

为实现铁尾矿固废材料的再生利用,提高工业固废利用率,以铁尾矿、磷渣、脱硫灰作为掺合料部分代替水泥制备混凝土,研究三元体系下钙相固废与铁尾矿协同作用对混凝土抗压强度的影响,测试不同水胶比、铁尾矿研磨时间、掺合料掺量及掺合料比例对混凝土抗压强度的影响。结果表明,混凝土抗压强度与水胶比呈正相关关系,机械研磨提高了铁尾矿的比表面积,有利于铁尾矿表面与自由水发生水化反应,30%掺量混凝土后期抗压强度较20%掺量下降不大,在铁尾矿比表面积为1589.3 m^(2)/kg,铁尾矿、磷渣、脱硫灰分别占胶凝材料的6%、16%、8%时制备的混凝土抗压强度最高,28 d抗压强度达到40.9 MPa。通过采用压汞法(MIP)和背散射电子成像技术(BSE)研究了混凝土的微观结构,结果表明,掺合料的掺入优化了混凝土的孔隙结构,促进了界面过渡区的发展。铁尾矿、磷渣、脱硫灰三元体系在30%掺量下对混凝土强度影响较小,可代替水泥制备混凝土。

In order to realize the recycling of iron tailing solid waste materials and improve the utilization rate of industrial solid waste,concrete was prepared by using iron tailing,phosphate slag and desulfurization ash as admixtures to partially replace cement,and the effect of the synergistic effect of calcium phase solid waste and iron tailing on the compressive strength of concrete under the ternary system was investigated.The effects of different water-cement ratio,iron tailing grinding time,admixture amount and admixture ratio on the compressive strength of concrete were tested.The results showed that the compressive strength of concrete was positively correlated with the water-cement ratio,mechanical grinding increased the specific surface area of iron tailings,which was conducive to the hydration reaction between the surface of iron tailings and free water,and the compressive strength of concrete at the later stage of 30%admixture did not drop much compared with 20%admixture.When the specific surface area of iron tailings is 1589.3 m^(2)/kg,iron tailings,phosphorous slag and desulfurization ash accounted for 6%,16%,8%cementing materials respectively,the concrete compressive strength is the highest,and the 28 d compressive strength reaches 40.9 MPa.Mercury intrusion porosimetry(MIP)and backscatter scattered electron(BSE)image analysis were used to study the microstructure of concrete,and the results showed that the admixture incorporation optimizes the pore structure of concrete and promotes the development of interfacial transition zone.The ternary system of iron tailings,phosphate slag and desulfurization ash has less effect on the strength of concrete at 30%admixture and can be used to prepare concrete instead of cement.