The Influence of Limestone Powder and Metakaolin Co-Blending on the Hydration Process and Mechanical Properties of Q-Phase Cement

A ternary system comprising Ca₂₀Al₂₆Mg₃Si₃O₆₈ (Q-phase), limestone, and metakaolin is proposed, and its hydration behavior, hydration product phases, microstructure, and mechanical properties are investigated and compared with pure Q-phase cement. The results indicate that the ternary system exhibits exceptional and sustained compressive strength even under a 40 °C environment, significantly outperforming pure Q-phase. The mechanism lies in that metakaolin effectively inhibits the transformation of metastable phase. Meanwhile, the interactions among Q-phase, limestone, and metakaolin further enhance the cementitious performance. The ternary system effectively addresses potential issues of strength loss in Q-phase cement application, and as a low-carbon cementitious material system, it holds promising potential applications.