Effect of Alkaline Solution Content on Strength and Chloride Induced Corrosion of Steel in Geopolymer Concrete Made from Fly Ash

Abstract

In this paper, the effect of alkaline solution content on compressive strength and corrosion behavior of steel reinforcement in geopolymer concrete (GPC) has been evaluated. For the study, fly ash was used as the source material for preparation of geopolymer concrete. The mixture of NaOH solution (10 M and 14 M) and Na₂SiO₃ solution was used as the alkaline solution. Alkaline solution contents of 190 and 210 kg/m³ were used in the preparation of geopolymer concrete mixes. Sodium chloride was added at the time of preparation of GPC mixes and its concentrations were 0% and 3% by mass of geopolymer solids content. From GPC mixes, cube specimens and prismatic reinforced concrete specimens were prepared. Half-cell potential and corrosion current density by linear polarization resistance (LPR) measurement were carried out on prismatic reinforced specimens. From obtained results, it is observed that there was no systematic variation in 28 day compressive strength of GPC with alkaline solution content and the compressive strength decreased in the presence of chloride ions. Further, GPC made with higher alkaline solution content showed higher probability of occurrence of reinforcing steel corrosion and higher corrosion current density as compared to that made with lower alkaline solution content.