Author(s):
D.V. Morris, B.N. Popov
Publication Date
November 1994
Abstract
Cement stabilization of backfill has been used for some time in mechanically stabilized earth type retaining walls. However, there has been no data on the corrosion life of galvanized steel reinforcement in this environment, which is intermediate in pH between normal soil and pure cement. Field observations had indicated a potential corrosion problem at a particular site in District 12.|As a result of the test program conducted during this project, the following conclusions were made. First, cement addition to backfill in the usual quantities (i.e. 7% or more) raised the pH environment to values close to that of normal concrete. At these levels corrosion rates of zinc coatings were not significantly accelerated -- if anything, corrosion rates were less than for unstabilized fill. Second, very small amounts of cement addition, of the order of 1% to 4% producing pH values significantly less than 12, could cause limited acceleration of corrosion. It is, therefore, advisable to control minimum cement levels and to encourage efficient mixing. Third, elevated corrosion rates were associated primarily with the presence of inorganic ions, both for stabilized and unstabilized fill. In the case of the problem site in District 12, this appeared to be the result primarily of unusually high sulfate content in the fill. Fourth, the use of crushed concrete as backfill did not accelerate corrosion. This material, therefore, appears to be acceptable for this application.
Report Number:
1359-1F
Keywords:
Earth Retaining Structures, Galvanized Steel Corrosion, Reinforced Earth, Retained Earth, Retaining Walls, Soil Cement, Soil Corrosion, Tiebacks
Link(s):
Document/Product
http://tti.tamu.edu/documents/1359-1F.pdf
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