United States Department of Transportation
i
Rehabilitation of Prestressed Concrete Bridge Components by Non-Electrical (Conventional) Methods
-
1999-02-01
-
[PDF-8.53 MB]
Details:
-
Creators:
-
Corporate Creators:
-
Contributors:
-
Corporate Contributors:
-
Subject/TRT Terms:
-
Publication/ Report Number:
-
Resource Type:
-
Geographical Coverage:
-
Edition:Final Report October 1991-September 1998
-
Contracting Officer:
-
Corporate Publisher:
-
Abstract:This report describes a technology review, field surveys, and laboratory investigations into the corrosion of prestressed concrete (PS/C) highway bridge elements and conventional repair methods used for these structures. Details of the technology review and field surveys are given in an Interim Report (FHWA-RD-95-041). Subsequent to completion of the field surveys, a laboratory program designed to evaluate corrosion performance of conventional concrete repair materials was initiated. Test specimens were precorroded by application of anodic current while exposed to chloride solutions. In order to study conventional concrete repairs, it was necessary to remove concrete from preselected areas on each purposely corroded test specimen and replace the chloride-contaminated/deteriorated original concrete with repair materials. Materials evaluated included conventional Portland cement concrete, latex-modified fiber-reinforced patching mortar, and silica fume concrete containing either organic or inorganic corrosion inhibitors. Specimens where concrete was not removed were used to study the effects of sealers and coatings applied on concrete surfaces to mitigate ongoing corrosion. All specimens were exposed for approximately 200 weeks to a 15% solution of sodium chloride after repair. At the conclusion of exposure, patches were removed from repair specimens and the steel and the applied coatings were examined. In many of the specimens, significant deterioration of the coatings applied to prestressing strands and reinforcing steel had occurred over the 4 years of severe exposure. The distress was greater for the steel coated with liquid epoxy coating than the companion area of steel coated with a zinc-rich product. Typically, there was more disruption of coating and corrosion of base steel in areas where latex-modified mortar had been used as a repair material than where conventional concrete or silica fume concretes were used. Corrosion was observed in repair areas where bulk chloride ion contents were below commonly accepted threshold levels. When tendon bundles were cut and pulled apart, corrosion was observed on the interior surfaces of the individual strands. It is likely that chloride ions penetrated into the interstices of the strand bundles while the specimens were precorroded, and prior to the repairs. Penetrating sealers and coatings were of limited effectiveness when applied to the surface of concrete specimens undergoing active corrosion
-
Format:
-
Funding:
-
Collection(s):
-
Main Document Checksum:
-
Download URL:
-
File Type:
