The paper presents the results and discussions of experiments conducted to investigate the effects of nano-SiO2 (nano Silicon Dioxide) on the compressive strength, porosity, flexural strength, and capillary absorption of concrete. The experiments involved testing 18 cylinders and beams with varying nano-SiO2 content while keeping the percentage of silica fume (SF) constant at 4%. A baseline test without SF or nano-SiO2 was conducted for comparison. The results showed that the compressive strength of the concrete increased with increasing nanoSiO2 content up to 2%, beyond which the increase plateaued. The initial increase in strength was attributed to the filling of voids and improved density, but higher nano-SiO2 percentages hindered uniform dispersion, limiting the strength improvement. The porosity test revealed that adding nano-SiO2 reduced porosity, with the most significant reduction observed at 0.5% nano-SiO2 content. However, further increases in nano-SiO2 had diminishing returns in terms of porosity reduction. Higher nano-SiO2 percentages resulted in less flowable concrete, indicating poor dispersion and limited benefit from the filling properties of the nanoparticles. Flexural strength increased with the addition of nano-SiO2, but the cost-effectiveness of this improvement was questioned. Steel fiber was found to be a more viable option for enhancing flexural strength. The coefficient of capillary absorption decreased with increased SiO2 dosage, indicating improved water resistance, but further analysis is needed to assess costeffectiveness compared to alternative materials or methods. In conclusion, while nano-SiO2 showed improvements in compressive strength, porosity reduction, and flexural strength, it was not considered cost-effective compared to other options such as silica fume, fly ash, or steel fiber. Future research should explore the interactions of multiple variables, including water-to-cement ratio and supplementary cementitious materials, to gain a more comprehensive understanding of concrete performance and optimize mix designs