关键词: 土壤聚合物, 添加剂, 凝结时间, 莫来石

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