辅助胶凝材料玻璃体结构与胶凝活性的研究进展

Industrial by-products or solid waste, such as blast furnace slag, coal-combustion fly ash et al., have long been used as supplementary cementitious materials (SCM) in Portland cement and concrete. Utilization of SCM can mitigate the problems caused by cement production, including high energy and natural resources consumption, massive carbon dioxide emission. To reach the desired high replacement levels (beyond 30wt%) of Portland cement without significant performance loss, triggering SCM reactivity is the key. However, from the point of view of material science, the empirical testing approach concerning macroscopic properties led to a quite fragmented understanding of SCM reactivity. In addition to their specific surface area, the hydraulic reactivity of SCM is highly dependent on the dissolution-precipitation reaction of the glass phase within the minerals. The glass structure of SCM can be simply expressed as the molar ratio between network modifer (e.g. Ca, Na) and network former (e.g. Si, Al), such as depolymerization degree in glass chemistry. Recent studies on CaO-SiO₂-Al₂O₃ glass enhance the understanding of the structure in terms of Si(Qⁿ(mAl)) polymerization units. The polymerization degree of the glass, saturation index in the solution, cation/anion species and their concentration and pH determine the dissolution rate of the glass structure. Besides, formation of precipitates changes the dissolution kinetics as well. This review offers a retrospection of the research efforts on the glass structure of SCM in relation to the hydraulic reactivity. The glass structures in terms of depolymerization degree and Si(Qⁿ(mAl)) are presented, respectively. The reactivity of the glass structure under different activation conditions is also elaborated. Therefore, it lays a foundation for the development of the building materials with low-carbon footprint, while stable quality and good durability of the building materials are maintained.