Abstract: To address the demand for special building materials with high early strength and rapid setting and hardening in emergency repair projects,and to explore high-value utilization pathways for bulk industrial solid waste in building materi als,this study proposes the preparation of a high-volume iron tailings sand mortar using alkali activation technology.The study utilizes fly ash (FA) and ground granulated blast furnace slag (GGBFS) as precursors,with iron tailings sand fully replacing natural sand as the fine aggregate.Through orthogonal experimental design,the effects of four key factors,namely the mass ratio of FA to GGBFS,NaOH solution concentration,water-binder ratio,and mortar-binder ratio,on the workability of fresh mortar and the mechanical properties of hardened mortar were systematically investigated.The results show that the primary and sec ondary influence order of each factor on the 24-hour compressive strength of mortar is the mass ratio of FA to GGBFS,the con centration of NaOH solution,the water-binder ratio and the cement-sand ratio.The GGBFS content is the decisive factor deter mining early strength,mainly because GGBFS can provide a rich calcium source for the system,promoting the formation of a large amount of dense C-(A)-S-H gel.Under the optimal mix ratio,the 24-hour compressive strength of mortar reaches 33.69 MPa,exhibiting excellent rapid hardening and early strength characteristics.Meanwhile,the iron tailings sand content reaches 66.7%,achieving efficient resource utilization of solid waste.This study provides scientific basis and technical support for the development of emergency repair materials with both excellent mechanical properties and environmental benefits.

Key words: rapid hardening and early strength,high-content iron tailings,alkali-activated,industrial solid waste,mortar performance