Study on microstructural evolutions and properties of the magnesium oxysulfate cement in the initial curing processes
Article
Wu, Z, Liu, H, Zhao, M et al. (2023). Study on microstructural evolutions and properties of the magnesium oxysulfate cement in the initial curing processes
. 37 10.1016/j.mtcomm.2023.107458
Wu, Z, Liu, H, Zhao, M et al. (2023). Study on microstructural evolutions and properties of the magnesium oxysulfate cement in the initial curing processes
. 37 10.1016/j.mtcomm.2023.107458
Magnesium oxysulfate (MOS) cement is a new type of cement building material with broad application prospects. The mechanical properties of MOS cement are closely related to the category of additives, and the content and process of hydration as well as their nanostructure. In particular, the nanostructures that have a significant impact on the mechanical properties of MOS require a thorough understanding. The morphology, heat properties, crystal processes and nanostructural changes of MOS cements had been studied by SEM, DTA/TG, XRD, and SAXS techniques. The new 5Mg(OH)2∙MgSO4∙7H2O (5−1−7) crystal phase in the MOS matrix crystallized in the form of micro-sized needles. Synchrotron radiation XRD experiments didn't show the growth of the 5–1–7 crystalline phase before the final setting time. The nanostructural changes of MOS cements were studied by in-situ SAXS technique. The SAXS measurements revealed that the nanostructural change was mainly related to the nanopores in the MOS cement matrix and there had different hydration processes in the samples prepared with pure MgO or light-burned MgO and different additives after immersion in water for about 460 min. Additionally, the size increases of nanostructures in the samples prepared with light-burned MgO and KH2PO4 additive indicated the growth of 5–1–7 crystal phase and a rough surface structure from 1251 to 1918 min. The SAXS results enrich the nanostructural understanding on changes in nanostructures in cements and provide knowledge orientation for MOS practical applications.
