Research progress of effects of composite mineral admixtures on cement hydration and microstructure

The preparation of composite mineral admixtures utilizing multi-source solid waste is a core pathway toward achieving low-carbon and high-performance cementitious materials. Focusing on the physical packing and chemical synergistic effects among multiple components, this paper elucidates the full-time-series regulation laws of four typical composite systems on cement hydration kinetics and microstructure evolution. Results indicate that a sequential hydration response mechanism is established based on the differences in the intrinsic reactivity of various components, which effectively mitigates and disperses the early hydration heat. Moreover, the dynamic balance between calcium demand and release accelerates the consumption of interfacial Ca(OH)₂ crystals. Through the isomorphous substitution of active Al, it induces the formation of C-A-S-H gels with low Ca/Si ratios and a high degree of polymerization. Simultaneously, multi-scale spatial packing and ultra-fineness technology thoroughly break through the early-age reaction inertia barrier of high-volume solid waste. Driven by the interfacial de-orientation effect and the in-situ filling of gels, interconnected capillary pores are profoundly refined into harmless nano-pores. Finally, future prospects are proposed from three dimensions: the synergistic activation of complex bulk solid waste, the in-situ dynamic tracking of mechanisms at the nanoscale, and data-driven intelligent reverse design, aiming to provide robust theoretical support for the research and development of novel green cementitious materials.