A Model for Estimating Resistivity of In-Service Backfill of Mechanically Stabilized Earth Walls Based on Minimum Resistivity and Degree of Saturation

Abstract

The resistivity of aggregates used as fill within mechanically stabilized earth (MSE) walls has been found to be a good indicator of its potential to corrode metal reinforcements. As such it is important to accurately measure the fill resistivity. Previous studies have found that resistivity is affected by the gradation of the material, as finer particles normally have much lower resistivity than coarse particles. The resistivity is also greatly dependent on moisture content. To estimate how the variation in moisture content can affect the resistivity, and the in-service performance of MSE walls, laboratory resistivity measurements were performed on 23 materials at varying moisture contents. The results were used to develop a model to estimate the resistivity of a given material knowing its minimum resistivity, porosity, and degree of saturation greater than 50%. Model predictions can potentially be used to estimate the resistivity of in-service wall fill and to harmonize field and laboratory resistivity measurements. The model could be used in future corrosion modeling that considers the seasonal or long-term moisture contents of the fill, similar to the recently developed Mechanistic Empirical Pavement Design (MEPDG) procedure.