Investigation of Mechanical Properties and Microstructural Development in Cement-Based Materials Incorporating Zinc Oxide Nanoparticles

This study investigates the impact of Zinc Oxide nanoparticles (ZnO NPs) on the mechanical properties and microstructural development of cement-based composites. Characterization using Scanning Electron Microscopy (SEM) and Dynamic Light Scattering (DLS) revealed uniformly distributed, spherical ZnO NPs with an average size of approximately 72 nm. X-ray Diffraction (XRD) and SEM analyses were performed on cement paste and mortar specimens with varying ZnO NP contents (1.0%, 1.5%, 2.0%, 2.5%, and 3.0% by weight). The results indicate that lower ZnO NP contents (1.0% and 1.5%) accelerate initial setting times, while higher contents (2.0%, 2.5%, and 3.0%) delay them due to the formation of clinohedrite (CaZn(SiO)₄•H₂O), which increases porosity and reduces matrix compaction. Calorimetric analysis showed decreased hydration heat with rising ZnO NP content, negatively affecting workability. This study highlights the dual effect of ZnO NPs in cement-based materials: low concentrations improve early-age mechanical performance, while higher amounts hinder hydration and microstructural integrity. These findings provide insights into optimizing ZnO NP dosage for the development of high-performance, nano-enhanced construction materials.