Electronic Thickness Gauge Measurements on a 36-year old Steel Bar Mat Reinforced MSE Wall

摘要

During road realignment activities in 2012 on the Ⅰ-495 Washington Capital Beltway, the Virginia Department of Transportation (VDOT) demolished a MSE wall originally built in 1976. The wall supported traffic on the interstate bridge ramp and was therefore salted each winter as part of VDOT's standard winter maintenance program; the wall did not have any observable performance issues. Demolition provided an opportunity for researchers at the Federal Highway Administration (FHWA) to investigate the condition of the reinforcement in the 36-year old wall and determine any key factors affecting corrosion related to the design, construction, and maintenance practices. Steel and soil samples were collected from various locations behind the concrete panels along the length of the wall to assess the thickness of the remaining zinc coating on the bar mats. This thickness was analyzed as a function of wall elevation and distance from the bridge abutment face. This paper will describe the corrosion sampling and testing program and present preliminary conclusions on the results.