Evaluation of Corrosion Potential of Subsoil Using Geotechnical Properties

Corrosion of underground pipelines is an important issue in the American pipeline industry. In 2002, the estimated annual cost was approximately US$7 billion for the monitoring, replacement, and maintenance of pipelines. Although significant improvements have occurred in corrosion engineering, the cost associated with the corrosion of buried pipes is still very high. According to current practices, physicochemical properties of subsoil, i.e., electrical resistivity, pH, redox potential, and sulfate and chloride concentrations, are widely used as indicators of the corrosive nature of soil. However, laboratory measurements of these parameters are often difficult due to time and budget constraints of projects. This paper evaluates the corrosion potential of subsoil using geotechnical properties. The study uses 15 specimens for the determination of geotechnical properties and electrical resistivity and the estimation of total sulfate and chloride content. The corrosion potential of the soil samples was evaluated from observed saturated minimum electrical resistivity and total sulfate and chloride content. The results indicate that the minimum saturated resistivity decreases and total sulfate and chloride content increases with the increase of liquid limits (LL), plasticity index (PI), activity, and cation exchange capacity (CEC). Therefore the corrosion potential of subsurface can be evaluated using geotechnical properties as a function of saturated minimum resistivity and total sulfate and chloride content. Furthermore, the pitting-type corrosion rate and decay in galvanized culvert pipe are estimated using electrical resistivity and are correlated with the geotechnical properties.