An Eco-Friendly Phosphogypsum-Based Cementitious Material: Performance Optimization and Enhancing Mechanisms

Abstract

Little published data were effective in decreasing the setting time and improving the strength development of phosphogypsum-based supersulfate cement (P-SSC) containing an excess of 40% phosphogypsum to achieve adequate field working and mechanical properties. This study aimed to optimize the application performance of P-SSC by wet grinding, the enhancement mechanism of which was discussed further. The wet grinding mainly refined and dispersed the phosphogypsum with the large particle size, improving the formation of ettringite by increasing the supersaturation of phosphogypsum. However, the release of impurities prolonged the setting time of P-SSC pastes, leading to a lower early strength. Short-time wet grinding destroyed the surface structure of slag with the small particle size, presenting a higher hydration degree. It seemed to have a more significant improvement of generated C-(A)-S-H gel, while treating P-SSC by wet grinding slightly enhanced strength development. Increasing the aluminate concentration by incorporating active aluminum phases in this process significantly promoted the generation rate of ettringite and weakened the negative effect of impurity release. Therefore, a feasible and effective method to prepare P-SSC pastes was proposed to realize the large-scale application of phosphogypsum in the building materials industry.