This study investigates the effect of cement replacement by oil shale grinded powder (OSGP) on the workability, mechanical properties, and durability of concrete. Four mixtures were prepared with OSGP ratios to cement of 0%, 10%, 20%, and 30%. OSGP was prepared by obtained oil shale from Wadi Al-Shallala at the north of Jordan, then grinded to fine particles and passed from 54 micro-meter sieve. X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), and Scanning Electron Microscope (SEM) tests for OSGP were conducted and the results were displayed. Workability, through slump test, was conducted for fresh concrete specimens after mixing. Compressive strength, flexural strength, and tensile strength were performed at the age of 28 days. The results showed a significant reduction in workability, compressive, flexural, and splitting tensile strengths as oil shale increased in the concrete mixture.

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.