Physical and microstructural properties of moc with alccofine at high temperatures

The growing environmental concerns associated with Ordinary Portland Cement (OPC), particularly its high carbon emissions and energy-intensive production process, have necessitated the development of sustainable alternatives in the construction industry. This study explores Magnesium Oxychloride Cement (MOC) as a potential eco-friendly binder and investigates the effect of incorporating Alccofine (AF)—a highly reactive industrial by-product—on the performance of MOC. MOC paste samples were prepared by partially replacing MgO with AF at 0%, 10%, 20%, and 30%, and subjected to calcination at 110 °C, 210 °C, and 250 °C. The specimens were tested for setting time, ultrasonic pulse velocity (UPV), compressive strength, and analysed for microstructural changes using Scanning Electron Microscopy (SEM). The results demonstrated that MOC sets significantly faster than OPC, with setting time increasing proportionally with AF content. Compressive strength improved consistently with both higher AF dosage and calcination temperature, with 30% AF-MOC at 250 °C showing the highest strength across all curing ages. UPV measurements confirmed improved internal densification and quality with increased AF. SEM analysis revealed enhanced formation of needle-like Phase 5 crystals and interlocking gel structures, particularly at 30% AF, contributing to reduced porosity and improved durability. Overall, the inclusion of Alccofine led to a denser microstructure, better mechanical performance, and greater thermal stability of MOC. These findings establish AF-modified MOC as a promising, sustainable alternative to conventional cement, particularly suitable for high-strength applications under elevated temperatures.