Investigation and Implications of Mechanically Stabilized Earth Wall Corrosion in Nevada

The Nevada Department of Transportation has more than 150 mechanically stabilized earth (MSE) walls at 39 locations. Wall reinforcement corrosion was found by accident during construction projects at two of these locations. The resulting investigations of these walls produced direct measurements of metal losses and electrochemical properties of the MSE-reinforced fill. One MSE wall was replaced with a cast-in-place concrete tie-back wall at great expense. A statistical analysis addresses the variability in measured corrosion and electrochemical data to predict corrosion behavior. The original MSE-reinforced fill approval electrochemical test results are significantly different from those measured in postconstruction investigations. A correlation has been developed between two distinctly different soil resistivity test methods: the Nevada T235B and AASHTO T-288 methods. Overprediction made by the Nevada T235B method has proven detrimental to the service lives of MSE walls. The internal stability analyses (using AASHTO 2007 load and resistance factor design specifications) of two remaining MSE walls at an intersection were also performed by using metal loss models developed from the statistical analysis. The findings of the study were subsequently extrapolated to other Nevada MSE walls. Through review of the reinforced fill approval data, suspect Nevada MSE walls have been identified relative to estimated reinforced fill aggressiveness.