磷、氟杂质对建筑石膏性能的影响研究

Study on influence of phosphorus and fluorine impurities on properties of building-purpose gypsum

以磷石膏应用为研究目标,通过向天然石膏中添加磷酸、氟硅酸、氢氟酸、磷酸氢钙,研究水溶磷、水溶氟、共晶磷对石膏砌块物理力学性能的影响。结果表明,水溶磷、共晶磷对石膏砌块凝结时间均有缓凝作用,力学性能随添加量增加而降低;共晶磷的影响小于水溶磷;水溶氟缩短了砌块凝结时间,降低了力学性能;水溶磷、水溶氟的共同作用对砌块具有促凝功能,在水溶磷、水溶氟总质量分数为0.15%时,石膏砌块力学性能出现最大值;随着水溶磷、水溶氟质量分数的增加,抗折抗压呈现断崖式下降。在含有0.2%共晶磷的石膏中加入水溶磷、水溶氟时,由于水化过程中共晶磷部分转化为水溶磷,导致凝结时间延长,力学性能下降。

Taking the application of phosphogypsum as study objective,the impact of water-soluble phosphorus,water-soluble fluorine,and eutectic phosphorus on the physical and mechanical properties of gypsum blocks is studied through incorporating phosphoric acid,fluorosilicic acid,hydrofluoric acid,and calcium hydrogen phosphate,respectively into natural gypsum.The findings reveal that both water-soluble phosphorus and eutectic phosphorus slow the setting time of gypsum blocks,and weaken mechanical properties with increasing dosages.The impact of eutectic phosphorus is less pronounced than that of water-soluble phosphorus.Water-soluble fluorine reduces both the setting time and mechanical properties of the blocks.The combined effect of water-soluble phosphorus and water-soluble fluorine accelerates the setting process of gypsum blocks.The optimal mechanical properties of gypsum blocks are achieved when the combined mass fraction of water-soluble phosphorus and fluorine is at 0.15%.As the mass fraction of water-soluble phosphorus and fluorine increases,there is a precipitous decline in both flexural and compressive strength.As water-soluble phosphorus and fluorine are added into gypsum containing 0.2%eutectic phosphorus,which results in a prolonged setting time and diminished mechanical properties because part of eutectic phosphorus converts to water-soluble phosphorus during the hydration process.