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Field surveys were performed on four reinforced earth retaining walls. Concrete facing units were used on each wall. The objective of these surveys was to obtain information concerning the susceptibility to corrosion of metallic elements (both embedded in backfill and in concrete) in these soil stabilization systems. The structures surveyed represented differing environmental conditions and materials. Both marine and inland structures were included, with ages ranging from 6 to 11 years.
A variety of field tests were carried out at each site. Field tests included visual and photographic surveys, delamination detection, electrical potential surveys, measurements of concrete and soil resistivities, measurements of concrete cover, and stray current testing. Powdered and core samples of concrete were returned to the laboratory for chloride analyses and rapid chloride permeability testing. Chemical and metallographic analyses were carried out on samples of soil and earth reinforcing strips.
Results indicate that two of the four structures surveyed exhibit corrosion problems that may limit their useful life. These include a reinforced earth structure located in a tidal estuary where aluminum alloy reinforcing strips are exposed to low resistivity and high chloride conditions and an interstate highway slope stabilization structure where galvanized metal earth-reinforcing strips are exposed to a highly alkaline backfill of nonuniform composition. Other structures surveyed showed little or no evidence of corrosion.
aluminum alloys, reinforcing steels, corrosion, precast concrete, panels, reinforced earth, soil stabilization, stray current corrosion, underground corrosion, zinc coatings
Senior research engineer, Construction Technology Laboratories, Portland Cement Association, Skokie, IL