泥因自身较低的胶凝活性和过高的重金属离子含量制约了其在建筑材料领域的应用，制备性能良好且经济环保的赤泥基胶凝材料以实现赤泥的大掺量利用，是赤泥绿色、高效应用中需解决的问题。采用电石渣-磷石膏活化赤泥-粉煤灰制备赤泥基胶凝材料(RFCG)，研究了电石渣-磷石膏比例、赤泥煅烧温度和密封高温养护时间，对RFCG强度发展规律的影响，并利用XRD、SEM-EDS和ICP-OES等测试技术，从微观机制上解释了RFCG的强度发展规律，并评估了RFCG的环境影响。结果表明，电石渣提供的OH-和赤泥中的Na2O促进了反应，生成了C-(A)-S-H和少量N-A-S-H凝胶，促进了RFCG的强度发展；磷石膏提供的SO42-加速AFt生成，通过填充微观孔洞的方式提升基体密实程度，从而提升强度，但过量的AFt导致基体出现微观裂缝，对强度的发展影响较大。煅烧处理提升了赤泥的硅铝离子浸出率，并减弱了赤泥中有机质的负面影响，使RFCG的强度大幅提高。在60 ℃下养护24h能有效提高RFCG的早期强度。所制备的RFCG稳定了重金属离子，一定程度上避免了二次污染，能够应用于路面基层、矿山填充等工程领域。

The low hydration activity and high heavy metal ion content of red mud restrict its application in the field of building materials, and the preparation of good performance and economic and environmental friendly red mud-based cementitious material to realize the large admixture utilization of red mud is a problem to be solved in the green and efficient application of red mud. Red mud-based environmental cementitious material (RFCG) was prepared by activated red mud and fly ash with calcium carbide slag and phosphogypsum. The effects of calcium carbide-phosphogypsum ratio, calcination temperature of red mud, and sealing high-temperature curing time on the strength law of RFCG were investigated, and XRD, SEM-EDS, and ICP-OES were used to explain the strength law of RFCG from the microscopic mechanism and assess the environmental impact of RFCG. The results showed that OH- provided by calcium carbide slag promoted the reaction and generated C-(A)-S-H and a small amount of N-A-S-H gel, which contributed to the strength development of RFCG; AFt generated by SO42- provided by phosphogypsum enhanced the densification of the matrix by filling the microscopic pores to improve the strength, but the excessive AFt led to the development of microcracks in the matrix, which had an impact on the strength development greater. Calcination treatment enhanced the silica-aluminum ion leaching rate of red mud and attenuated the negative effect of organic matter in red mud, resulting in a substantial increase in the strength of RFCG. Conservation at 60 °C for 24 h effectively improved the early strength of RFCG. The prepared RFCG stabilized heavy metal ions, avoided secondary pollution to a certain extent, and could be applied in engineering fields such as pavement subgrade and mine filling.

TU526

云南省科技厅重大科技专项计划(202102AG050043)