磷再生石膏、脱硫再生石膏热性能与力学性能的变化研究

Research on Pyrolysis Characteristics and Mechanical Properties Changes of Phosphorus Recycled Gypsum and Desulphurized Recycled Gypsum

通过DSC/TG,SEM,BET,粒径分析及水化温升曲线对磷再生石膏、脱硫再生石膏热性能和力学性能的变化进行研究并分析其变化机理.结果表明,再生石膏热稳定性降低,磷再生石膏两次脱水温度分别降低4℃和2℃,脱硫再生石膏两次脱水温度也都降低2℃;再生石膏力学性能也是降低的,磷再生石膏强度降幅和吸水率增幅都较小,分别为15%-30%和22.40%,而脱硫再生石膏变化幅度较大,分别为45%-70%和76.61%,但两种再生石膏的脱水温度和力学性能几乎相同.分析表明,再生石膏热稳定性的降低是由于它具有较小的颗粒度所致,再生建筑石膏较大的比表面积、较小的粒度及颗粒分布不均是其力学性能降低的主要原因,而磷石膏较差的晶型使得其力学性能降幅较小.

By using DSC/TG, SEM, BET, particle size distribution and hydration temperature curve, the pyrolysis characteristics and mechanical properties of phosphorus recycled gypsum, desulphurized recycled gypsum and their changing mechanism were studied. The results indicated that the pyrolysis characteristics and mechanical properties of recycled gypsum were decreased, the twice dehydration temperatures of phosphorus recycled gypsum dropped 4℃ and 2℃, respectively, and desulphurized recycled gypsum both reduced by 2℃. The low decrease in strength and modest increase in water absorption were seen in phosphorus recycled gypsum, and the rate was 15 %-30% and 22.40%, respectively. But the 45%-70% decrease in strength and 76. 61% increase in water absorption were possessed by desulphurized recycled gypsum, which was much greater than phosphorus recycled gypsum, and approximately the same dehydration temperatures and mechanical properties were observed by the two recycled gypsum. The analysis has shown that the reduction in pyrolysis characteristics is due to the decrease of particle sizes in recycled gypsum. The main reason of the great difference of mechanical properties between raw gypsum and their recycled gypsum are the increase in specific surface area, decrease in particle sizes and the uneven distribution of recycled gypsum. And the poor crystal of phosphorus gypsum results in the low decrease rate of its recycled gypsum.