In response to rising CO₂ emissions in the cement industry and the growing demand for durable offshore engineering materials, calcium sulphoaluminate (CSA) cement concrete, known for its lower carbon footprint and enhanced corrosion resistance compared to Ordinary Portland Cement (OPC), is increasingly important. However, the chloride transport behavior of CSA concrete in both laboratory and marine environments remains underexplored and controversial. Accordingly, the chloride ion transport behaviors and mechanisms of CSA concrete in laboratory-accelerated drying-wetting cyclic environments using NaCl solution and seawater, as well as in marine tidal environments, were characterized using the rapid chloride test (RCT), X-ray diffraction (XRD), mercury infiltration porosimetry (MIP), and thermogravimetric analysis (TGA). The results reveal that CSA concrete accumulates more chloride ions in NaCl solution than in seawater, with concentrations 2–3.5 times higher at the same water–cement ratio. Microscopic analysis indicates that calcium and sulfate ions present in seawater facilitate the regeneration of ettringite, thereby increasing the density of the surface pore structure. The hydration and repair mechanisms of CSA concrete under laboratory conditions closely resemble those in marine tidal conditions when exposed to seawater. Additionally, this study found that lower chloride ion concentrations and pH levels inhibit the formation of Friedel’s salt. Therefore, laboratory experiments with seawater can effectively simulate CSA concrete’s chloride transport properties in marine tidal environments, whereas NaCl solution does not accurately reflect actual marine conditions.

Calcium sulfoaluminate (CSA) cement has emerged as a low-carbon alternative to ordinary Portland cement (OPC), offering reduced CO₂ emissions and rapid strength development. However, the role of the ferrite phase in CSA systems remains underexplored. This study investigates the influence of ferrite-phase composition on CSA cement properties through targeted clinker design, hydration analysis, and macro–micro performance testing. Nine clinker formulations were synthesized by systematically increasing the ferrite content (10–30%) while adjusting belite (C₂S) proportions, using limestone, bauxite, and supplementary Fe₂O₃/SiO₂. Results reveal that the ferrite phase enhances the formation and stabilization of ye’elimite (C₄A₃Š) during clinkering and reduces low-activity transitional phase products. Increasing the iron-phase content appropriately improves early strength by promoting ettringite (AFt) formation and refines pore structures to enhance later strength development. The maximum strength improvement is achieved when the target ferrite-phase content is set to 15%, showing a 25.1% increase in 1 d strength and an 11.5% increase in 28 d strength. While ferrite phases and C₂S ensure long-term strength gains, excessive ferrite content reduces C₄A₃Š availability, limiting early AFt formation and compromising initial strength. These findings highlight the dual role of the ferrite phase in optimizing CSA cement performance and sustainability, providing a foundation for designing ferrite-rich, low-carbon binders.

With the increasing volume of municipal solid waste incineration residues (MSWIR), effectively managing this ash has become an urgent issue. Due to the mineral components and cementitious properties of MSWIR, its potential application in cement concrete is receiving growing attention. This paper reviews the chemical composition of MSWIR from different regions and the properties of cement-based materials containing MSWIR. It discusses the advantages and disadvantages of various resource utilization pathways for MSWIR, investigates the challenges faced in using MSWIR as a mineral resource for producing cement-based materials, and analyzes the possible causes. Additionally, it provides feasible solutions to address these challenges. This review indicates that the physicochemical properties of MSWIR exhibit significant regional characteristics. Although the incorporation of MSWIR often weakens the performance of cement-based materials, it demonstrates considerable potential as a raw material for cement, a supplementary cementitious material, and a substitute for concrete aggregates when its threshold is properly controlled. Both incineration fly ash (IFA) and incineration bottom ash (IBA) possess distinct advantages and disadvantages in their resource utilization pathways. It is worth noting that while the short-term performance of MSWIR products meets regulatory requirements, their long-term performance requires further investigation.