Positive effects of novel nano-zirconia on flexural and compressive strength of Portland cement paste

•The object of research is to improve concrete mechanical properties.•Nano zirconia has been prepared via simple and low-cost hydrothermal method.•Nano zirconia has been introduced to concrete at different dosage.•1.5%wt of nano zirconia has been obtained as the optimum weight percent.•In higher dosage than 1.5%wt the performance of concrete slightly decreases.