Portland Cement Partially Replaced by Blast Furnace Slag and Multi-Walled Carbon Nanotubes: Effect on Corrosion Resistance of Carbon Steel Reinforcement in 3% NaCl

摘要

A partial replacement for Portland cement (PC) through supplementary cementitious materials is analternative technique to reduce carbon steel corrosion in reinforced concrete under exposure to marineenvironment. Here, the effect of blast furnace slag (BFS) and carbon nanotubes (CNTs) admixturesinto PC on the electrochemical corrosion resistance of carbon steel reinforced concrete was assessedby electrochemical impedance spectroscopy (EIS) and polarization systems during immersion in 3.5wt% NaCl media. The higher compressive strength was observed for BFS-CNT sample which can beattributed to the pozzolanic reaction of BFS filler, the formation of denser microstructure andacceleration of the hydration process. The polarization results show that the concrete samplescontaining CNTs admixture had a lower value of corrosion current density and corrosion rate revealingthe superior performance than the other samples. The EIS measurements indicated that BFS-CNTsample was most effective for enhancing the corrosion resistance of the steel rebar due to the decreaseof water absorptivity and chloride ion permeability..