Research And Application Of Phosphogypsum-based Self-leveling Material

Phosphogypsum is a by-product produced by the phosphate fertilizer industryduring the wet process of phosphoric acid,4.5-5.5tons Phosphogypsum aregenerated when per ton of P2O5are produced. It is estimated that the accumulativetotal of Phosphogypsum is over300million tons throughout China. Growingstockpiles of phosphogypsum not only occupies plenty of lands, waste of resources,and also causes serious pollution to the surrounding soil, water and air. Therefore,the efficient use of phosphogypsum resources is related to the sustainabledevelopment of agriculture, phosphorus chemical and related industries in ourcountry and affects national recycling economy directly. Currently, there have been alot of research which phosphogypsum was made into low value-added buildingmaterials, and less research of preparation of high value-added building materials,such as self-leveling material and so on.Based on the theoretical foundation of high-strength gypsum cementitiousmaterials preparation, study of various variables of atmospheric hydrothermalprocess affecting on the crystal morphology of phosphorus-based high-strengthgypsum plaster and the optimum process parameters are presented in the paper. Theeffects of plasticized materials and inorganic phosphorus-based additive materials onthe performance of phosphorus-based high-strength gypsum plaster which is thestructural material in the PGSL are discussed and provide theoretical guidance andapplication reference of phosphogypsum based self-leveling material (PGSL). Themain results obtained are as follows:1. We can obtian the phosphorus-based high-strength gypsum plaster reachesJC/T2038-2010"α-type high-strength gypsum" in the provisions of α30levelswhen the atmospheric hydrothermal process parameters: the solution containing25wt%～30wt%CaCl2concentration, solid-liquid ratio is one, kept the temperatureat95℃to100℃, and the crystal agent of NSArange from0.10%to0.20%.2. Plasticized agents can significantly improve the flow properties of PGSL, thePCS has the most significant effect, and the best content is0.2%; Retarder can extend initial setting and final setting time of PGSL, the SC has the most significanteffect, and the most appropriate content is0.2%.3. Cement is the inorganic admixture materials of PGSL, it can improve themechanical properties and the water resistance, when its content is8%, themechanical properties to achieve the best; the superfine admixture can improve thework performance of PGSL, ultra-fine mineral powder which effect is very obvious,when the content is between10%-20%, PGSL has the best performance.