Investigation of Concrete Deterioration at South Florida Water Management District Structure S65E.

摘要

This report documents the findings of a concrete deterioration study of South Florida Water Management District Structure S65E. The study examined water quality at the S65E site and concrete cores from deteriorated, repaired, and non-deteriorated areas of the structure. In addition, a geochemical water- rock reaction simulation was performed to investigate the potential for dissolution of the concrete based on local water quality. The predominant form of deterioration observed was severe loss of both paste and coarse aggregates from the surface of the concrete with larger losses in high-flow areas of dam piers than in the lock chamber. Concrete from deteriorated areas exhibited significant loss of Pleistocene limestone coarse aggregates and paste, while the siliceous, fine aggregates were unaffected. Concrete distress may be caused by dissolution of soluble phases and biodeterioration, which can result in localized acidification at the surface and direct or chemical consumption of mineral phases present in concrete. The use of siliceous aggregates, along with efforts to minimize porosity / permeability, and improved acid resistance would likely improve the durability of the repair material, as well as better protect the underlying concrete from subsequent deterioration.