Influence of nano-cementitious materials on improving the corrosion resistance and microstructure characteristics of concrete

Concrete is a building material widely used in construction due to its excellent mechanical properties such as compressive strength and bond strength with steel reinforcement. Strength and durability are the key factors that need to be satisfied in the design of reinforced concrete structures. The objective of this paper is to improve the bond strength and corrosion resistance of concrete by using supplementary nano cementitious materials such as Nano Metakaolin (NMK) and Nano Silica Fume (NSF). The addition of nano cementitious materials will help in enhancing the mechanical properties of concrete by improving the micro-structure. Effective bond between concrete and reinforcing steel ensures the load transformation among structural elements. The specimens are exposed to either chloride-induced acceleration-based corrosion test or chloride-induced immersion-based corrosion test. Investigations were conducted to evaluate the compressive strength, bond strength and corrosion resistance of concrete. Specimens with corrosion inhibitor/anti corrosive coating exhibited poor bond strength when compared to concrete with nano metakaolin and nano silica fume. The corrosion potential was found to be highly negative for control specimens. Specimens exposed to accelerated corrosion test exhibited lower bond strength with higher mass loss and low yield strength in the rebars. Extent of damage due to the effect of corrosion was analysed by physical observations and image analysis. Concrete with Nano Metakaolin exhibited better bond strength and corrosion resistance than those of the other specimens. Effect of nano Cementitious material on improving the micro-structure characteristics of concrete was confirmed by SEM. It was evident from the SEM results that, addition of NMK and NSF in concrete had a significant contribution in improving the bond strength and corrosion resistance.