Abstract: In order to find safe and low-cost salt-activated materials to prepare soil polymers,light burned metakaolin was obtained after firing Guangxi kaolin at 850 ℃ for 4 h and added with different amounts of condensed aluminum phosphate,lithium phosphate and lithium silicate (3%,4% and 5% of the metakaolin mass,respectively) as the additives to prepare soil polymers.Subsequently,the mixtures of metakaolin with lithium silicate,lithium phosphate or condensed aluminum phosphate were added to the corundum castable system,respectively,and the performance of the castables was compared with that of calcium aluminate bonded corundum castables.The effects of the additives on the solidification time,phase composition and microstructure of the obtained soil polymers as well as the soil polymers on the properties of the castables were explored.The results show that:(1)the solidification time of the soil polymers increases from 2 h to 5 h with the increasing additive addition,and the preferred addition is 4%;(2)at 20 ℃,condensed aluminum phosphate reacts with metakaolin to form gelling SiP₂O₇,while lithium silicate and lithium phosphate react with metakaolin to form LiAlSiO₄,forming a layered structure or a gelling film attached to the surface of metakaolin,thus resulting in a gelation effect of soil polymers;(3)at 1 100 ℃,soil polymers gradually form mullite,and layered metakaolin becomes thinner and cross connected;at 1 600 ℃,the mullitization of soil polymers is complete,forming needle and rod structures that cross connect with each other,and a small amount of liquid is generated,densifying the sample;(4)replacing calcium aluminate cement with soil polymers in the same proportion as the binder,the castable has a certain gap in performance compared to the calcium aluminate cement bonded castable.

Key words: soil polymers, additives, solidification time, mullite

摘要： 为了寻找安全且价格低廉的盐类激发剂制备土壤聚合物,将广西高岭土在850 ℃保温4 h得到轻烧后的偏高岭土,再分别添加不同量(分别为偏高岭土质量的3%、4%和5%)的缩合磷酸铝、磷酸锂、硅酸锂作为添加剂制备了土壤聚合物。随后分别将硅酸锂、磷酸锂、缩合磷酸铝与偏高岭土混合物加入到刚玉质浇注料体系中,并与铝酸钙结合刚玉质浇注料的性能进行对比。研究了添加剂对制备的土壤聚合物凝结时间、物相组成和显微结构的影响,以及土壤聚合物对浇注料性能的影响。结果表明:1)土壤聚合物的凝结时间随添加剂添加量的增加而增加,凝结时间在2~5 h,优选添加量为4%(w);2)在20 ℃时,缩合磷酸铝与偏高岭土生成胶凝性的SiP₂O₇,硅酸锂、磷酸锂与偏高岭土反应生成LiAlSiO₄,同时形成类似层状结构物质或胶凝膜附着在偏高岭土表面,使得土壤聚合物产生胶凝作用;3)1 100 ℃时土壤聚合物逐渐形成莫来石,层状偏高岭土颗粒变薄并交叉连接;1 600 ℃时土壤聚合物完全莫来石化,形成相互交叉连接的针棒状结构,并有少量液相生成使得试样更加致密;4)土壤聚合物同比例替代铝酸钙水泥作为结合剂制备的浇注料,在性能方面与铝酸钙水泥结合的浇注料相比有一定的差距。

关键词: 土壤聚合物, 添加剂, 凝结时间, 莫来石