磷石膏-铜尾矿砂混合料的土工性能及微观机理研究

Geotechnical Performance and Micro-Mechanism of Phosphogypsum-Copper Tailings Sand Mixture

为实现固废资源大宗利用及"以废治废"的目的,将磷石膏与铜尾矿砂拌和制备成混合料,外掺水泥用于公路路基填筑。通过对混合料进行土工性能试验,探索磷石膏与铜尾矿砂的质量比对混合料土工性能的影响,结合现代分析测试方法,对混合料的硬化机理及微观变化进行研究。结果表明:磷石膏液限较高而铜尾矿砂强度特性较低,两者都无法单独作为路基填筑材料使用,当磷石膏与铜尾矿砂按质量比4∶6混合使用时,混合料的土工性能较佳;混合料硬化是水泥水化导致的,水化产物中的钙矾石、C-S-H凝胶等能够填补混合料颗粒间隙,形成紧密集合体,致使混合料硬化。

The phosphogypsum and copper tailings sand are mixed to prepare a mixture,and cement is added for highway roadbed filling,which can realize the large-scale utilization of solid waste resources and the purpose of“waste treatment by waste”.The geotechnical performance test of the mixture was used to explore the influence of the mass ratio of phosphogypsum and copper tailings sand on the mixture’s geotechnical performance,combined with modern analysis and testing technology to study the hydration-hardening mechanism and micro-mechanism of the mixture.The results show that neither phosphogypsum nor copper tailings sand can be used alone as roadbed filling materials because of the higher liquid limit of phosphogypsum and the lower strength characteristics of copper tailings sand.When phosphogypsum and copper tailings sand are mixed with a mass ratio of 4∶6,the geotechnical performance of the mixture was better.The hardening of the mixture is caused by the hydration of the cement.Hydration products such as ettringite and C-S-H gel can fill the gap between the particles of the mixture and form a compact aggregate,which causes the mixture to harden.