磷石膏复合水泥基充填料的制备及其强度性能研究

Study on Preparation and Strength Properties of Phosphogypsum Composite Cement-Based Filling Material

基于“绿色矿山”的理念,选用磷石膏、水泥与尾砂等矿物固废制备充填料,开展流动性、泌水率和强度性能的测试,结合X射线衍射和扫描电镜技术测试矿物成分与微结构特征,最后对充填料水化机理进行了初步探究。结果发现:水泥基充填料在膏体质量分数为72%~75%且减水剂浓度为0.2 mol/L时,坍落度和泌水率指标可以满足浆料泵送的要求;磷石膏改性作用使得水泥基充填料的早期强度显著上升;磷石膏掺量为15%时材料的无侧限抗压强度最高;层状水化硅酸钙与针状钙矾石为磷石膏复合充填料中的主要水化产物;磷石膏的改性使得水化反应早期的水化硅酸钙和钙矾石含量提高,形成致密结构,从而加速了材料早期强度的形成。

Based on the concept of green mine,phosphogypsum,cement,tailings and other mineral solid wastes were selected to prepare filling materials,and the fluidity,bleeding rate and strength properties were tested.Combined with X-ray diffraction and scanning electron microscopy,the mineral composition and microstructure characteristics were tested.Finally,the hydration mechanism of this filling material was preliminarily explored.The results show that when the mass fraction of paste is 72%-75%and the concentration of water reducer is 0.2 mol/L,the slump and bleeding rate of cement-based filling material can meet the requirements of slurry pumping.The modification of phosphogypsum increases the early strength of cement-based filling material significantly,when the content of phosphogypsum is 15%,the unconfined compressive strength of the materials is the highest.Layered calcium silicate hydrate and acicular ettringite are the main hydration products in phosphogypsum composite filling material.The modification of phosphogypsum increases the content of hydrated calcium silicate and ettringite in the early stage of hydration reaction,and forms a dense structure,thus accelerating the formation of early strength of the material.