This investigation explores the impact of various proportions of nano-silica and nano-titanium dioxide on M40 and M50 grade concrete, utilizing a polycarboxylate superplasticizer. Previous studies have shown that partial replacement higher than 2% causes a decrease in strength. Thus, the mix design includes a control mix (CM1), 1%NS+0%NT(NST2), 0.5%NS+1%NT(NST3), and 1%NS+1%NT(NST4). The study involved casting:72 cubes (150x150x150mm), 96 cubes(100x100x100mm), 24 cylinders of different sizes (300x150mm,120x100mm, and 50x100mm), and 24 prisms(100x100x500mm). Mechanical and durability properties were assessed at 28 and 56 days. They revealed that the NST4 mix of M40 achieved the highest increase in compressive strength at 7 days. The splitting tensile strength varied with NST4 showing a 2% & 9% (M40 & M50) increase and NST2 an 11% & 5% (M40 & M50) decrease. NST3 achieved optimum flexural strength with 1%(M40) and 16%(M50) increases in strength compared to CM1. The enhanced concrete demonstrated the lowest chloride permeability as 214(NST3) and 161(NST3&NST4) coulombs in M40 and M50, respectively. HCl Acid resistance with compressive strength loss in NST4 mixes with (HCl-2.33%, H2SO4-3%) and (HCl-2.67%, H2SO4-4.67%) for M40 and M50 at 56 days, with the least weight losses in the same mixes. All the concrete mixes had UPV values above 4.5 km/s, confirming excellent quality of concrete as per the provisional codes.