钢渣粉-水泥复合激发矿物掺合料固化磷石膏的试验研究

EXPERIMENTAL STUDY ON SOLIDIFICATION OF PHOSPHOGYPSUM WITH STEEL SLAG POWDER-CEMENT COMPOSITE EXCITED MINERAL ADMIXTURE

基于对磷石膏的再利用,以磷石膏为主要原料,用钢渣粉和少量水泥复合激发矿物掺合料来固化磷石膏。通过碱度水平、水化产物和微观结构的变化来阐述强度变化的原因,考察水泥置换钢渣粉量和矿物掺合料掺配比对磷石膏固化效果的影响。结果表明:当水泥置换钢渣粉量超过5%后,会造成复合材料28 d的显微结构破坏,导致强度降低。磷石膏的固化效果随着粉煤灰含量的增加而减弱。体系碱度水平对复合材料的强度发展起着至关重要的作用。微观分析表明:适量的钢渣粉和磷石膏能够促进活性SiO_(2)和Al_(2)O_(3)水化生成C-(A)-S-H和针柱状AFt,AFt晶体和残余的磷石膏相互连接形成骨架结构,C-(A)-S-H将其牢固的粘结在一起并填充于孔隙中,形成具有高强度的密实结构。

Based on the reuse of phosphogypsum,phosphogypsum is used as the main raw material to solidify phosphogypsum with steel slag powder and a small amount of cement composite excitation mineral admixture.The reason of strength change is explained by the change of alkalinity level,hydration products and microstructure,and the influence of the amount of steel slag powder replaced by cement and different proportions of mineral admixtures on the curing effect of phosphogypsum is investigated.The results show that when the amount of steel slag powder replaced by cement exceeds 5%,the microstructure of the composite will be damaged after 28 days,resulting in the strength reduction.The solidification effect of phosphogypsum decreases with the increase of fly ash and the decrease of slag powder.The alkalinity level of the system plays an important role in the strength development of composite materials.The microscopic analysis shows that the appropriate amount of steel slag powder and phosphogypsum can promote the hydration of active SiO_(2)and Al_(2)O_(3)to form C-(A)-S-H and needle-like AFt.The AFt crystal and residual phosphogypsum are connected to form a skeleton structure,and C-(A)-S-H firmly binds them together and fills them in the pores,forming a dense structure with high strength.