Assessing the effect of sodium nitrite as corrosion inhibitor against the corrosion of steel rebar in alkali-activated concrete
Rohit Ranjan, Satya Ranjan Prusty, Biswajit Rout, Ramakanta Panigrahi, Sanghamitra Jena
Abstract
The aim of this study is to investigate the effectiveness of corrosion inhibitor against chloride-induced corrosion of steel rebar in fly-ash (FA) and GGBS (ground granulated blast furnace slag) and Nanofine-based alkali-activated concrete. The Alkali-Activated Concrete (AAC) was prepared from FA, ground granulated blast furnace slag (GGBS), and Nanofine with Sodium hydroxide (NaOH) and Sodium Silicate (Na 2 SiO 3 ) solutions. The concentration of NaOH varies to 10 M, 12 M, and 14 M, and all the specimens were subjected to accelerated corrosion, to perform the non-destructive test after the corrosion of the steel rebars. Fourier Transform Infrared (FTIR), scanning electron microscope (SEM), Energy dispersive X-ray spectroscopy (EDS), and Electron Backscatter Diffraction (EBSD) were used to examine the microstructure of AAC in the presence of Nano-Fine GGBS (NF), Sodium Chloride (NaCl), and NaNO 2 and to compare the strength and corrosion properties with AAC and OPC . The ratio of sodium silicate to sodium hydroxide was taken as 2.5 and the solution-to-binder ratio was taken as 0.5. The compressive strength and ultrasonic pulse velocity (UPV) test of the Nano-fine based alkali-activated concrete increases as compared to the control concrete. The increase in the dosages of corrosion inhibitor and nano-fine increases the compressive strength of the control concrete and alkali-activated concrete. The half-cell potential of the control concrete and nano fine admixed with alkali-activated concrete mixes with different molarities is uncertain. The increases in the dosages of corrosion inhibitors reduce the occurrence of corrosion in the steel reinforcement rebars.