Practical Model for Three-Stage Corrosion Behavior of Galvanized Steel Reinforcement in Soil

Abstract

Failure of mechanically stabilized earth (MSE) walls attributed to the corrosion of galvanized steel in soil has raised concern on the adequacy of current design requirements. In this work, a numerical model was developed to calculate the corrosion rate of galvanized steel in soil at three different stages of corrosion by considering key soil corrosion parameters, such as resistivity, temperature, moisture content, pH, and oxygen availability. Results show that the proposed model is in agreement with widely accepted empirical models, and can be used for the service-life design and risk assessment of MSE walls and to determine the optimum zinc cover thickness.

Corrosion resistance of hot-dip galvanized steel in simulated soil solution: A factorial design and pit chemistry study

“…Therefore, a galvanized steel structure installed in British Columbia has a different underground corrosion behavior compared to those reported for relatively warmer locations. Moreover, using empirical models developed to predict the soil corrosion rate of galvanized steel might underestimate the service life of galvanized steel assets installed in British Columbia, as they are based on corrosion data collected from warmer locations [74].…”

“…For soil with the resistivity of more than 3,000 Ω.cm, the AASHTO model predicts that the corrosion rate of a Zn coating would be 1.0 µA/cm² (or a corrosion rate of 15 µm/year) [76]. Although this model was found to be conservative, it predicts cumulative metal loss less than 2,000 µm after 75 years of service life for a galvanized steel [74]. The low and high levels of chloride, sulfate and citric acid concentration shown in Table 1 covers both the nonaggressive and aggressive soil AASHTO criteria.…”

Influence of soil chemical characteristics on corrosion behaviour of galvanized steel

“…The soil mass behind the pre-cast concrete wall is generally composed by selected granular backfill material reinforced by metal strips or grids. These soil reinforcing elements have tensile strains generally smaller than those of the surrounding soil under the same stress condition, and hence they are usually assumed to be inextensible in practice [17,18]. The use of MSE reinforced systems has increased in the last decades worldwide, with the construction of thousands of walls and slopes.…”

“…The tensile elements consist of metal and polymer strips and grids. The walls are designed to transfer the loads to the tensile elements, attached to the wall face [18]. The most used soil-reinforcement elements for retaining walls on transportation projects include galvanized steel.…”