Optimization of light-burnt magnesia content in MOC-based construction composites

Abstract

This study examines the effect of the content of industrial-grade magnesium oxide (MgO-I) powder, which contains various impurities, on the properties of quartz sand-filled MOC composites. Samples were prepared with MgO-I excessive content ranging from 50.0 to 100.0 wt.% relative to the stoichiometric amount required for MOC Phase 5 formation. X-ray diffraction, X-ray fluorescence, optical microscopy, scanning electron microscopy, and energy-dispersive spectroscopy were used to characterize the phase and chemical composition, microstructure, and elemental distribution. Mechanical properties, including flexural and compressive strength, were also evaluated. The results demonstrate that increasing the excessive MgO-I content leads to a densification of the composite’s microstructure, effectively filling pores. This densification significantly enhanced both compressive and flexural strength, with increases of 22.6 % and 41.1 %, respectively, for the 100 wt.% excess sample compared to the 50 wt.% excess sample.