Influence of the degree of saturation on carbon steel corrosion in soil

•Monitoring of corrosion of carbon steel in soil by EIS.•Impact of the degree of water saturation on carbon steel corrosion.•Modeling of non-uniform corrosion in unsaturated soil. The corrosion behaviour of carbon steel was investigated in artificial soils of various saturations with 3% NaCl solution. The carbon steel corroded uniformly at slower rates in saturated soil and non-uniformly at higher rates in unsaturated soils. The corrosion current density (icorr) was measured by electrochemical impedance spectroscopy, and the percentage of corroded surface area (Aanode) was evaluated using a laser displacement metre. The corrosion current density (icorr(a)) of the corroded surface area was determined by dividing the icorr by (Aanode/100). Based on the results obtained, the influence of the degree of water saturation on carbon steel corrosion is discussed.