铅离子对复合磷酸盐磷酸镁水泥水化硬化特性的影响∗

摘要

In this paper,the effect of lead ion on the hydration of compound phosphate based magnesium phos-phate cement and its leaching properties was studied.The results show that the compressive strength of com-pound phosphate based magnesium phosphate cement decrease with the increase of lead ion content.High con-tent of lead ion has no significant effect on the setting time of magnesium phosphate cement.During the hydra-tion of compound phosphate based magnesium phosphate cement,lead ion has no significant effect on the pH of the system,but the hydration exothermic peak is delayed by lead ion adding.The lead ion also reduced the amount of hydration heat and affected the degree of crystallization of the main hydration products.In the late hydration reaction of composite magnesium phosphate cement,when the content of lead nitrate is 10% or more the obvious Pb2 P2 O7 diffraction peak can be found.The leaching toxicity of lead ion is 43μg/L and it is lower than the national standard.%研究了铅离子对复合磷酸盐磷酸镁水泥水化硬化特性的影响及其在复合磷酸盐磷酸镁水泥中的稳定性。实验结果表明，复合磷酸盐磷酸镁水泥抗压强度随着铅离子掺量的增加而降低，其中硝酸铅掺量达到10％时，复合磷酸盐磷酸镁水泥的各个龄期的抗压强度发生明显下降。铅离子对复合磷酸盐磷酸镁水泥凝结时间没有明显影响。在复合磷酸盐磷酸镁水泥水化过程中，铅离子对水泥体系的 pH 值影响不大，但能够造成水泥水化放热峰出现的时间延迟，水化放热的总量减少并影响主要水化产物的结晶程度。在复合磷酸盐磷酸镁水泥水化反应后期，当硝酸铅掺量达到10％以上时，在水化产物中出现了较为明显的 Pb2 P2 O7的衍射峰。复合磷酸盐磷酸镁水泥固化铅离子的浸出毒性试验结果(43μg/L)远低于国家标准要求(5 mg/L)。