Investigation of the influence of nano-silica on the corrosion resistance and bond strength characteristics of concrete

Corrosion significantly weakens the bond between concrete and steel reinforcements and reduces the strength of reinforced concrete (RC) structures. This study experimentally examined the impact of corrosion on RC beams with Nano silica (NS), focusing on the bond strength behavior through pull-out and flexural bond tests. NS was added in varying percentages (0.5 %, 1 %, 1.5 %, and 2 %) by binder weight to enhance the bond behavior and concrete strength. The compressive strength of concrete, measured at 28 days, ranged from 15.88 % to 31.77 % with different NS proportions. At 60 day, the compressive strengths ranged from 5.50 % to 15.67 % with a normal superplasticizer (NS) at different proportions. Adding 1.5 % NS to the binder weight yielded an optimal mix with enhanced strength properties. Flexural strength, measured at 28 days, ranged from 16.53 % to 42.99 % with various NS proportions. The split tensile strengths at 28 days ranged from 7.90 % to 15.79 % with different NS proportions. The findings showed superior mechanical properties in concrete with NS compared with those without NS. For corrosion resistance, an accelerated corrosion process was induced for the optimal mix using the impressed current technique with a constant voltage and varying current. Pull-out specimens with a 70 mm clear cover and flexural bond specimens with a 20 mm clear cover underwent different hours of accelerated corrosion. The bond strength results indicated that concrete with the optimal NS percentage had lower mass loss and superior corrosion resistance, suggesting a higher bond strength and improved resistance to radial and shear stresses.