Effect of Alkaline Liquid and GGBS Replacement Level on Corrosion Behaviour of Reinforcing Steel in Chloride Contaminated Geopolymer Concrete Made with Fly Ash and GGBS

Abstract

In this paper, the effect of molarity of sodium hydroxide (NaOH) solution on corrosion behaviour of reinforcing steel in chloride contaminated geopolymer concrete (GPC) prepared with fly ash and GGBS was studied for different GGBS replacement levels. In this work, GPC was prepared with various molarity of NaOH solution such as 8, and 14 M with GGBS replacement levels of 0, 15, and 45%. Sodium chloride concentrations of 0 and 3% of geopolymer solids (by mass) were added to the alkaline liquid during the preparation time of GPC mixtures. Prismatic reinforced GPC specimens were made for half-cell potential measurement and corrosion current density (Icorr) by linear polarization resistance (LPR) measurement. The obtained results showed that the 28 days compressive strength of GPC increased with raise in molarity (i.e. from 8 to 14 M) of NaOH solution. Further, higher compressive strength was achieved in all the GPC mixes made with 45% GGBS replacement level as compared to other replacement levels. In addition, decrease in compressive strength was observed in GPC mixes added with 3% sodium chloride (NaCl). The higher probability of occurrence of corrosion and higher Icorr of steel reinforcement were observed in 3% NaCl admixed geopolymer concrete. The increase in Icorr of steel reinforcement was observed with raise in molarity of NaOH solution. Further, the Icorr of steel reinforcement in GPC decreased with increase in GGBS replacement level i.e. from 15 to 45%.