Effect of Ferrous Alloy Type, Beetroot Juice, Deicer Type and Concentration on Early-Stage Corrosion Behavior of Buried Pipes

Abstract

In this laboratory study, the corrosion behavior of ASTM A1008 CS Type B carbon steel (C1008), ASTM A48 Class 35 gray cast iron (GCCL35), and ASTM A536 65-45-12 ductile cast iron [Ductile(65-45-12)] was examined in a simulated soil solution in the presence and absence of beetroot juice (beet juice), a bioderived additive. Two types of deicers, including 23% NaCl and 30% MgCl2 at different dilution ratios (1:30 and 1:90), were included as the test media to simulate the practical cases of buried pipes adjacent to roadways. The corrosion behavior of the metallic samples was examined by the measurements of open circuit potential and linear polarization resistance. In addition, electrochemical impedance spectroscopy was used to study the corrosion product layer. Surface analysis of the samples was carried out using energy dispersive X-ray spectroscopy and scanning electron microscopy methods. The results showed that beet juice had corrosion inhibitory properties in diluted 23% NaCl at both dilution ratios. However, in the case of diluted 30% MgCl2 solution, corrosion inhibition was limited to a dilution ratio of 1:30, which shows a more pronounced effect of dilution on the corrosion inhibition in 30% MgCl2 compared to 23% NaCl. The protection mechanism mainly involved blocking the anodic active sites by an organic passive layer. C1008 samples showed the lowest corrosion rate in the presence and absence of beet juice in NaCl and MgCl2 solutions. A more protective layer formed on the samples in NaCl solution compared to MgCl2, which may be due to the effect of ionic strength on the solubility.