Effects of CuO Nanoparticles on Microstructure, Physical, Mechanical and Thermal Properties of Self-Compacting Cementitious Composites

In the present study, split tensile strength of self-compacting concrete with different amount of CuO nanoparticles has been investigated. CuO nanoparticles with the average particle size of 15 nm were added partially to self compacting concrete and split tensile strength of the specimens has been measured. The results indicate that CuO nanoparticles are able to improve the split tensile strength of self compacting concrete and recover the negative effects of polycarboxylate superplasticizer on split tensile strength. CuO nanoparticle as a partial replacement of cement up to 4 wt% could accelerate C-S-H gel formation as a result of increased crystalline Ca(OH)2 amount at the early ages of hydration. The increase of the CuO nanoparticles more than 4 wt% causes the decrease of the split tensile strength because of unsuitable dispersion of nanoparticles in the concrete matrix. Accelerated peak appearance in conduction calorimetry tests, more weight loss in thermogravimetric analysis and more rapid appearance of related peaks to hydrated products in X-ray diffraction (XRD) results all also indicate that CuO nanoparticles up to 4 wt% could improve the mechanical and physical properties of the specimens. Finally, CuO nanoparticles could improve the pore structure of concrete and shift the distributed pores to harmless and few-harm pores.