改性磷石膏的强度与孔结构的研究

本工作研究了矿物掺合料(矿渣、粉煤灰)和激发剂(熟石灰和水泥)对磷石膏强度的影响,并且探索了水泥对磷石膏耐水系数的影响。此外对磷石膏改性处理后的微观形貌和孔结构进行了分析。研究结果表明:矿渣和粉煤灰均能提高磷石膏的强度,且矿渣对磷石膏强度的增强作用更明显；但两者对磷石膏耐水性的增强作用并不明显,矿渣掺量过多时会由于延迟钙矾石的形成而导致石膏开裂。水泥和熟石灰作为激发剂时可以增强磷石膏的强度,熟石灰的增强作用更明显。水泥对磷石膏的耐水性能有一定的增强作用。磷石膏的水胶比、养护龄期和矿物掺合料可以改变其孔隙率,但不会改变其孔径分布；粉煤灰可以提高石膏的孔隙率,并且改变其孔径分布；水泥会降低石膏的孔隙率并改变其孔结构。

Mechanical Strength and Pore Structure Analysis of Modified Phosphogypsum

This work aimed to study the influence of mineral admixtures (slag and fly ash) and the activators (slaked lime and cement)on the mechanical properties of phosphogypsum. Moreover, the influence of cement on the water resistance coefficient of phosphogypsum was investigated. Additionally, the microstructures and pore structures of modified phosphogypsum were studied. Results showed that the strength of phosphogypsum was improved by slag and fly ash (the improving effect by slag was more ob-vious). While, they had little influence on improving the water resistance of phosphogypsum. Excessive amount of slag led to more cracks of phosphogypsum due to the delayed formation of ettringite. As activators, slaked lime and cement can enhance the strength of phosphogypsum, the reinforcement of hydrated lime was more obvious. Moreover, cement could improve the water resistance of phosphogypsum. Water-binder ratios, curing ages and mineral admixtures could affect the porosity of phosphogypsum, however these parameters had little influence on the pores distribution. Fly ash could improve porosity and transform the pore diameter distribution. Additionally, the cement not only reduced the porosity but also transformed pore structure.