Transformation of Tricalcium Silicate Crystalline Forms in Steel Slag Under Cooling Processes and Mechanisms for Enhancing Hydration Activity

Abstract

As a metallurgical bulk solid waste, stockpiled steel slag risks land occupation, soil and groundwater pollution. Its low-activity T 1 -C 3 S (Ca 3 SiO 5 ) regulated to high-activity M 3 -C 3 S boosts hydration activity and reduces harmful releases via lattice solidification, meeting environmental and industrial needs.Aligned with green metallurgical processes, this study achieved T 1 -C 3 S-to-M 3 -C 3 S transformation in steel slag by optimizing cooling parameters (lowenergy physical cooling replacing chemical modification)-via pure-phase C 3 S preparation, characterization and cooling-induced crystal form research. Meanwhile, first-principles calculations explored C 3 S polymorphs' reactivity-electronic structure relationship.Results indicate: increased cooling rate attenuates the lattice amplitude of pure-phase C 3 S; water cooling at synthesis temperature achieves a relatively high T 1 -C 3 S mass fraction. For steel slag under specific water-cooling temperature, MgO solid solution effect effectively promotes T1-C 3 S→M 3 -C 3 S conversion to maximize M 3 -C 3 S content (without additional chemical reagents); rapid cooling accelerates steel slag particle cracking, significantly elevates pore parameters, and optimizes compatibility with construction material feedstock.This study optimizes cooling process to achieve T 1 -C 3 S-to-M 3 -C 3 S transformation in steel slag, mitigates solid waste secondary pollution, clarifies mechanisms, and supports steel slag high-value utilization & metallurgical green process upgrading.