Graphene oxide as a nanoadditive in cementitious composites: A comparative study of portland and magnesium oxychloride cement binders

The addition of graphene oxide (GO) to cement-based materials can improve their mechanical performance and durability. However, there are few direct comparisons between different binder systems. While GO has been widely studied in Portland cement (PC), its effect on alternative binders like magnesium oxychloride cement (MOC) has usually been explored separately and under different experimental conditions. This study offers a direct comparison of GO-modified PC and MOC composites, with both prepared and tested under the same conditions. Composites containing up to 1.0 wt% GO were assessed using XRD, SEM, EDS, XRF, MIP, and thermal analysis, as well as mechanical and hygric testing. The results indicate that GO does not change the basic phase structure of either binder system but leads to different responses based on the system. Flexural strength increased by as much as 17.6% in PC and 13.4% in MOC composites. Compressive strength showed an optimal level at moderate GO amounts but declined at higher levels. Water absorption and transport were slightly lower, especially with increased GO amounts. In MOC composites, water resistance improved, shown by higher softening coefficients and retained compressive strength. Thermal conductivity and volumetric heat capacity increased with more GO content. These findings show that GO's effect varies with the type of binder. In hydration-based PC systems, its impact mainly appears in microstructure and mechanical response. In crystallization-based MOC systems, changes in water performance are more noticeable. The study offers a controlled comparison that aids in designing GO-modified cement-based materials for specific engineering uses. • GO effects compared in PC and MOC binding systems. • Strength controlled by pore redistribution and GO dispersion. • Non-linear porosity–strength relationship demonstrated. • Moisture transport linked to capillary connectivity changes. • Thermal response explained by competing porosity and GO effects.