为解决红黏土水稳性差、易崩解的缺陷，采用工业固废［粉煤灰（fly ash, FA）、磷石膏］协同水泥（cement, C）对红黏土进行改良处理。通过室内试验探究了工业固废-水泥改良红黏土的力学特性、水稳性能和微观机理。结果表明：随着磷石膏替代粉煤灰比率（R）的增加，改良土强度呈现先增大后减小的变化趋势。当水泥掺量为7%，R ＝ 7%时，改良土最大干密度提高2.6%，7 d无侧限抗压强度（unconfined compressive strength, UCS）提高11%，28 d UCS提高57%，满足路用底基层承载标准；7 d养护试样饱水后无明显变化，抗崩解能力增强，28 d试样水稳系数达到92.9%，水稳系数提高1.61倍。微观结果分析表明，磷石膏适量替代粉煤灰促进了新水化产物钙矾石和水化硅酸钙（calcium-silicate-hydrate, C-S-H）的生成，土体由碎散的颗粒状转变为更致密的胶凝网络结构，增强了红黏土颗粒间的黏结，同时填充了孔隙。研究结果验证了工业固废-水泥改良红黏土作为路基填料的可行性，为工程实践提供了坚实的理论基础与依据，同时拓宽了工业固废的再利用途径。

In order to solve the defects of poor water stability and easy disintegration of red clay, industrial solid waste [fly ash(FA), phosphogypsum] combined with cement (C) was used to improve red clay. The mechanical properties, water stability and micro-mechanisms of the industrial solid waste-cement amended red clay were investigated through indoor tests. The results show that the strength of the improved soil shows a trend of increasing and then decreasing with the increase of the ratio (R) of phosphogypsum replacing fly ash. When the cement doping is 7% and R = 7%, the maximum dry density of improved soil increases by 2.6%, the 7-day unconfined compressive strength (UCS) increases by 11%, and the 28-day UCS increases by 57%, which meets the bearing standard of subgrade for road use. There is no obvious change in the water-filled specimen after the 7-day maintenance, the resistance to disintegration is enhanced, and the water stability coefficient of the specimen reaches 92.9% in the 28-day maintenance. The water stability coefficient of the specimen reaches 92.9%, and the water stability coefficient increases 1.61 times. The microscopic analysis shows that the replacement of fly ash by phosphogypsum promoted the generation of new hydration products of ettringite and calcium-silicate-hydrate (C-S-H), which transforms the soil body from fragmented granular to a denser gel network structure, enhances the bonding between the red clay particles, and fills up the pore space at the same time. The results verifies the feasibility of industrial solid waste-cement-amended red clay as roadbed fill, provides a solid theoretical foundation and basis for engineering practice, and broadened the reuse of industrial solid waste.