Carbon Dioxide Uptake by MOC-Based Materials

Featured Application The highest potential of magnesium oxychloride cement (MOC) is its capability to be used as a component of low-energy building composite materials while acting as a CO2 sink. The results of this contribution also show that MOC can be used as a binder in advanced building materials that have particular properties, and therefore specific application potentials. Formation and hardening of this material are rather fast, so the material can be used in quick repairs as well as a protection layer. This property is also beneficial for use in prefabrication, due to the possibility of unmolding after a shorter time compared to Portland cement (PC) materials, so the whole production process can be considered more effective. Somewhat significant importance should be given to its ability to capture CO2, which not only makes it more eco-friendly, but also improves its mechanical properties. Abstract In this work, carbon dioxide uptake by magnesium oxychloride cement (MOC) based materials is described. Both thermodynamically stable magnesium oxychloride phases with stoichiometry 3Mg(OH)(2).MgCl2.8H(2)O (Phase 3) and 5Mg(OH)(2).MgCl2.8H(2)O (Phase 5) were prepared. X-ray diffraction (XRD) measurements were performed to confirm the purity of the studied phases after 7, 50, 100, 150, 200, and 250 days. Due to carbonation, chlorartinite was formed on the surface of the examined samples. The Rietveld analysis was performed to calculate the phase composition and evaluate the kinetics of carbonation. The SEM micrographs of the sample surfaces were compared with those of the bulk to prove XRD results. Both MOC phases exhibited fast mineral carbonation and high maximum theoretical values of CO2 uptake capacity. The materials based on MOC cement can thus find use in applications where a higher concentration of CO2 in the environment is expected (e.g., in flooring systems and wall panels), where they can partially mitigate the harmful effects of CO2 on indoor air quality and contribute to the sustainability of the construction industry by means of reducing the carbon footprints of alternative building materials and reducing CO2 concentrations in the environment overall.