化学预处理对磷石膏基复合胶凝材料性能的影响

研究了不同液固比和不同溶液浓度的化学预处理方式对磷石膏pH值、残余磷含量、磷石膏基复合胶凝材料凝结时间和力学性能的影响,进一步分析了预处理方式对磷石膏基复合胶凝材料水化产物物相组成及微观形貌的影响.结果表明:磷石膏的pH值与预处理溶液的液固比呈二次函数递增关系,与溶液浓度呈线性函数递增关系;溶液液固比的增加能降低残余磷含量,但溶液浓度的增加会抑制磷的去除;碱溶液预处理通过增加磷石膏的pH值来产生促凝效应,去离子水或自来水预处理通过减少残余磷含量来减弱缓凝效应;预处理能促进水化反应的进行,加速早期钙矾石的生成,缩短凝结时间,提高早期强度.

Effect of Chemical Pretreatment on the Properties of Phosphogypsum BasedComposite Cementitious Materials

The effects of chemical pretreatment with different liquid solid ratio and solution concentration on the pH value and residual phosphorus content of phosphogypsum and the setting time and mechanical properties of phosphogypsum based composite cementitious materials were studied. The influence of the liquid solid ratio and solution concentration on the composition and micro morphology of the hydration products of phosphogypsum based composite cementitious materials were further analyzed. The test results show that the pH value of phosphogypsum has a quadratic function relationship with the liquid solid ratio and a linear function relationship with the pretreatment solution concentration. The increase of liquid solid ratio can reduce the residual phosphorus content, while the increase of solution concentration inhibits the phosphorus removal. Alkali solution pretreatment can increase the pH value of phosphogypsum to produce an acceleration effect, while deionized water or tap water pretreatment can reduce the retardation effect by reducing residual phosphorus content. Chemical pretreatment can promote the hydration reaction, accelerate the formation of early ettringite, shorten the setting time and improve the early strength.