Hybrid effects of graphene oxide-zeolitic imidazolate framework-67 (GO@ZIF-67) nanocomposite on mechanical, thermal, and microstructure properties of cement mortar

The addition of two-dimensional nanomaterials, such as graphene oxide (GO), and three-dimensional nanomaterials, such as zeolitic imidazolate framework-67 (ZIF-67), has shown great promise in improving the characteristics of cement-based systems. Consequently, a thorough understanding of the synergistic interactions between 2D and 3D nanomaterials in cement-based mortars is necessary. However, there is a lack of research on the use of graphene oxide-zeolitic imidazolate framework-67 (GO@ZIF-67) nanocomposites. Accordingly, this study investigated the hybrid effects of GO@ZIF-67 nanocomposites on the mechanical strength, hydration kinetics, shrinkage performance, and microstructural features of cement mortars. The GO@ZIF-67 nanocomposite was synthesized and added to the cement mortar at various concentrations (0.3, 0.4, and 0.5 wt %). The developed nanocomposite cement mortar was characterized using SEM-EDS, XRD, and DSC-TGA. The results indicated that the hybrid GO@ZIF-67 slightly improved the compressive strength of the cement paste, with a synergistic effect observed at specific concentrations. However, microstructural analysis revealed that the presence of hybrid nanomaterials did not facilitate the assembly and regulation of hydration crystal growth, nor did it significantly impede growth, resulting in minimal effects on the properties of cement mortar. Additionally, the nanocomposite influenced the hydration reactions and the formation of specific hydration products, introduced defects, and weakened the microstructure of the cement mortar. Moreover, an increase in the hybrid nanocomposite content led to higher drying shrinkage and water absorption, indicating a reduced durability of the cement mortar. Further research is required to optimize the use of GO@ZIF-67 nanocomposites in cement mortars to achieve the desired balance of properties.