The storage of red mud has seriously damaged the ecological environment, and its utilization is urgent. The roles of particle size fraction of red mud on the geopolymer properties was investigated, to provide guidance for the preparation of red mud-based geopolymer. The composition variation, workability, mechanical strength, and microstructure of each red mud fraction were analyzed, and the results show that the chemical composition changed with the classification. The fluidity decreased first and then increased with the decrement of particle fraction, and all the specimens showed the rheological characteristics of Herschel–Buckley model. The specimens with coarser and finer particles both had excellent mechanical strength and lower porosity. The microstructure of red mud-based geopolymer with different red mud particle fractions was analyzed by FTIR, XRD and SEM–EDS. The results showed that the main hydration products were geopolymer gel (N-A-C-S-H). And the particle fraction has a little effect on the kinds of hydration products. Finally, the particle fraction of red mud was classified according to the properties of red mud-based geopolymer.

赤泥的储存严重破坏了生态环境，迫切需要利用。研究了赤泥粒度分数对地质聚合物性能的影响，为赤泥基地质聚合物的制备提供指导。分析了每个赤泥级分的组成变化，可加工性，机械强度和微观结构，结果表明化学组成随分类而变化。流动性首先下降，然后随着颗粒分数的减少而增加，并且所有标本都表现出Herschel-Buckley模型的流变特性。具有较粗和较细颗粒的样品均具有优异的机械强度和较低的孔隙率。通过FTIR，XRD和SEM-EDS分析了具有不同赤泥颗粒含量的赤泥基地质聚合物的微观结构。结果表明，主要的水合产物是地质聚合物凝胶（NACSH）。而且颗粒分数对水合产物的种类影响很小。最后，根据赤泥基地质聚合物的性质对赤泥的颗粒级分进行了分类。