铁尾矿砂混凝土耐久性能的试验研究

Experimental study on durability of tailings concrete

通过6组不同尾矿砂替代率制备试件,开展尾矿砂混凝土抗冻融、抗渗性能和氯盐腐蚀后强度变化及尾矿砂混凝土水化产物的电子显微镜微观扫描分析,探究尾矿砂对混凝土耐久性能影响的规律。试验结果表明:尾矿砂混凝土的冻融循环后的质量损失和相对弹性模量随尾矿砂替代率的增加而降低;尾矿砂替代率不大于20%时,尾矿砂混凝土的抗渗性能随替代率的增加而增加,替代率大于20%时,抗渗性能随替代率的增加而减少,尾矿砂混凝土的抗渗系数为1.78×10^-5~5.96×10^-6cm/h;界面黏结特征显示尾矿砂与水泥水化物黏结表面结构致密,随着尾砂掺量的增加,微孔结构逐渐粗化;建议工程采用替代率40%~60%尾矿砂制备混凝土,以实现工业废料的循环利用。

Six groups of tailings concrete specimens were prepared with different substitution rates of tailings.The experiment explores the influence of tailings on durability of tailings concret by the anti-freeze and thawing,anti-permeability,strength changes after chloride corrosion and hydration products tested by electron microscopy.The results show that the mass loss and relative elastic modulus of tailings concrete after freeze-thaw cycle decrease with the increase of tailings replacement ratio.When the replacement ratio of tailings is 0~20%,The impermeability of tailings concrete increases with the increase of the replacement rate of tailings.When the replacement ratio of tailings is 20% ~100%.The impermeability of tailings concrete decreases with the increase of the replacement rate of tailings.The impermeability coefficient of tailings concrete is 1.78 ×10-5~5.96 ×10-6 cm/h.SEM results show that the surface structure of tailing sand bonding with cement hydrate is compact and pore structure analysis revealed a coarsening of micro-pore structure with an increase of the tailings content.It is suggested that the mixed fine aggregate with a substitution rate of 40%~60% can be used to prepare tailings concrete.