Effect of high temperature modification of mineral powder and quicklime on properties of phosphogypsum cement based materials
Due to the inevitable incorporation of impurities in phosphogypsum,its quality is poor,which further hinders the application of phosphogypsum.The effect of quicklime high-temperature modified phosphogypsum on the strength of cement-based materials was explored by using phosphogypsum and Portland cement as raw materials,and then the improvement ef-fect of mineral powder on the defects of insufficient strength and rapid coagulation of high amount phosphogypsum cement-based materials was studied.Finally,XRD and SEM were used to analyze the hydration products of phosphogypsum cement-based materials,and the improvement mechanism of quicklime and mineral powder on the performance of phosphogypsum cement-based materials was revealed.The results showed that quicklime could successfully eliminate acid impurities in phosphogypsum at high temperature,improve the strength of the cementitious material,and taking into account the environ-mental protection and strength properties,the optimal amount of quicklime was 2％.The addition of mineral powder could further improve the strength of the cementitious material,delay the initial and final setting time of phosphogypsum cement-based material.With the continuous increase of mineral powder content,the strength of the cementitious material showed a trend of first increase and then decreased at 28 d.Taking into account all aspects of performance,the optimal amount of min-eral powder was 20％.In addition,after adding mineral powder,the cementitious material generated interlaced hydroxylapa-tite in the microstructure at 28 d,which was structurally stable and conducive to the development of mechanical properties of phosphogypsum cement-based materials.
万方数据
维普
