Editorial: Magnesia-based cementitious materials

Magnesia-based cementitious materials (MBCMs) primarily consist of magnesium oxide (MgO) and they react with various raw materials to form cementitious products. Their diverse hydration processes and resultant products endow these materials with numerous performance characteristics and also provide the possibility for targeted regulation of their properties. Typically, magnesium oxide combined with soluble salts forms magnesium phosphate cement (MPC), magnesium oxysulfate cement (MOS) and magnesium oxychloride cement (MOC), which are characterised by rapid setting, early strength development and high bonding strength. When reacting with active silico-aluminous materials, magnesium oxide forms magnesium silicate cement (MSC), whose main hydration products are magnesium silicate hydrate and hydrotalcite. This cement offers advantages like good water resistance and low alkalinity, promising to provide a favourable environment for the application of non-steel fibres. Accelerated carbonation of MBCMs yields high early strength and the capacity for strong carbon dioxide sequestration. Furthermore, their good compatibility with organic components presents an opportunity for developing magnesium-based organic–inorganic hybrid materials. These unique properties, distinct from traditional calcium-based materials, enable MBCMs to demonstrate broad application prospects and low carbon dioxide characteristics in areas such as rapid repair, fire protection, corrosion resistance and hazardous waste solidification, indicating potential for development into a new class of cementitious material systems.However, issues such as the uneven geographical distribution of magnesium resources and insufficient strength development in humid environments limit the large-scale application of MBCMs. In recent years, researchers have made significant progress in low-cost preparation, performance improvement and the development of new cementitious material systems based on magnesia. This special issue on MBCMs in Advances in Cement Research presents the latest research advances in areas such as the mechanisms for improving the water resistance of MPC and MOC, setting control of magnesium potassium phosphate cement (MKPC) and the long-term mechanical properties of reactive magnesia cement.Li et al. (2025) studied the effect of microsilica on the long-term water resistance of MKPC, testing its mechanical properties and the evolution of hydration products over 540 days in a water environment. Liu et al. (2025) used chitosan phosphate to activate the surface hydroxyl groups of nanosilica, investigating the impact of nanosilica loaded with chitosan phosphate on the development of mechanical properties in MOC cement under water exposure. Ardoğa et al. (2025) examined changes in the mechanical properties of reactive magnesia cement mortars incorporating fly ash over 360 days, clarifying the effects of magnesium oxide content, curing age and curing environment on the strength development of reactive magnesia cement. Pyo et al. (2025) explored the regulation of the setting and hardening process of MPC by zinc oxide (ZnO), analysing the influence of zinc oxide dosage on the hydration temperature, compressive strength and hydration product phases of MPC. They also compared zinc oxide with boric acid and analysed the role of zinc oxide in the hydration process of MPC.Current research and applications of MBCMs demonstrate a positive development trend, particularly in regions rich in magnesium resources like China, where applications of MBCMs are becoming increasingly widespread. These fundamental research achievements not only address existing problems but also provide crucial theoretical support for advancing the engineering applications of MBCMs.