Assessing corrosion of mechanically stabilized earth wall reinforcement

727363838Final; Apr. 2010-Sept. 2010.PDFTech ReportUT- 10.202689191Retaining wallsEarth wallsReinforced earthUtahUtah. Dept. of Transportation. Research DivisionGerber, Travis M.Billings, Daniel A.Brigham Young University. Dept. of Civil and Environmental EngineeringNTL-HIGHWAY/ROAD TRANSPORTATION-Soils and GeologyUS Transportation CollectionThe primary objective of this study was to extract reinforcement coupons from select MSE walls and document the extent of corrosion. In doing this, a baseline has been established against which coupons extracted in the future can be compared. A secondary objective of this project was to develop and assess techniques for removal of coupons on two-stage MSE walls. Twenty-two wire coupons were extracted from MSE walls that are approximately 11 to 12 years old. Based on field observations, coupon galvanization appeared to be intact but exhibited a variable amount of white oxidation product. In some places the galvanization appeared to have flaked or spalled from the underlying steel, and a minor amount of localized steel corrosion was observed on several of such specimens. Based on laboratory acid-stripping tests, the average thickness of the galvanization on all of the extracted coupons currently exceeds the minimum value specified for the time of installation. Because the initial conditions are unknown, a reliable corrosion rate could not be determined using the direct measurement methods employed in this study. However, the data collected regarding current conditions can be used as baseline information going forward to compute corrosion rates in the future. No readily discernable difference in corrosion conditions as a function of distance away from the wall face was found. There was significance difference in the coupon pullout resistance between one-stage and two-stage MSE walls. The reasons for this behavior and their implications for design and performance should be investigated further