Experimental investigation on the performance of concrete incorporating nano-silica and nano-titanium dioxide

The incorporation of nano-sized mineral additives has emerged as an effective approach to enhance the microstructure and mechanical performance of cementitious materials; however, comparative information on the individual effects of nano-silica (NS) and nano-titanium dioxide (NT) across different concrete grades remains limited. Therefore, this study investigates the influence of NS and NT as partial cement replacements on the mechanical properties of M20, M30, and M40 concrete. Concrete mixes incorporating 2%, 4%, and 6% NS and NT were evaluated for workability and mechanical properties after 7, 28, and 90 days of curing. The results indicated that both nano-additives enhanced concrete performance, with an optimum replacement level of 4%. Compared with the control concrete, the optimum NT and NS mixes improved the 90-day compressive strength by approximately 15.6% and 11.8%, respectively. The improved performance was attributed to enhanced particle packing, pore refinement, and accelerated hydration, resulting in a denser cement matrix. However, increasing the nano-additive content to 6% reduced workability and mechanical performance due to particle agglomeration, which hindered uniform dispersion and hydration. Overall, both NS and NT enhanced concrete performance, with NT exhibiting slightly greater improvements than NS at the optimum replacement level.