Tailoring the pore structure and compressive strength of magnesium slag compacts through temperature-controlled carbonation curing

• Published in: Construction & building materials 2024-08, Vol.441, p.137496, Article 137496
• Main Authors: Wu, Boqiang, Zhu, Shibin, Wang, Xiaodong, Zhang, Yuehong, Sun, Luyi, Zhang, Haibo, Liu, Songhui
• Format: Article
• Language: English
• Subjects: CaCO3; Carbonation; Magnesium slag; Microstructure; Temperature
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2024.137496

Despite magnesium slag's potential as a sustainable construction material, the effects of temperature-controlled carbonation curing on its properties and microstructure remain poorly understood. This study investigates the influence of elevated CO2-curing temperatures on the compressive strength, carbonation products, and microstructure of magnesium slag compacts by using XRD, TGA, FT-IR, SEM, and LF NMR. Results show optimal compressive performance at 85℃, attributed to the formation of magnesian calcite (MgxCa1-xCO3). This carbonation product exhibits larger grain size, and higher morphological quality, and adopts a mechanically interlocked distribution, enhancing strength despite lower compactness. Temperature significantly affects the morphology and microstructure of carbonation products, with calcite and aragonite predominating between 45℃-65℃. At 45℃, compacts show higher compactness. The study provides insights into temperature effects on ion mobility, dissolution-precipitation, formation energy, Gibbs free energy, and nucleation barrier in CaCO3. These findings advance the understanding of temperature-controlled carbonation curing of magnesium slag, contributing to its potential applications in sustainable construction. •Magnesia slag compacts exhibit optimal compressive strength at 85 °C curing.•Magnesian calcite with interlocked distribution enhances strength at 85 °C despite lower density.•Higher temperatures promote Mg incorporation into calcite over aragonite formation.