| Title | Electrochemical Chloride Extraction : Influence of Concrete Surface on Treatment |
|---|---|
| Record ID | 19934 |
| Personal Name Creator |
Clemeña, Gerardo G.; Kelly, R. G.; Sharp, Stephen R.; Virmani, Y. Paul; Stoner, Glenn E.; Kelly, Robert G. |
| Corporate Creator | Virginia Transportation Research Council (VTRC); United States. Department of Transportation. Federal Highway Administration. Turner-Fairbank Highway Research Center; University of Virginia. Dept. of Materials Science and Engineering |
| Corporate Contributor |
United States. Department of Transportation. Federal Highway Administration. Office of Infrastructure Research and Development |
| Publisher | Turner-Fairbank Highway Research Center; United States. Federal Highway Administration |
| Publication Date | 20020901 |
| Language | English |
| Abstract | One bridge restoration technique available for reducing corrosion-induced concrete deterioration, which removes chloride ions while simultaneously realkalizing the concrete adjacent to the steel, is electrochemical chloride extraction (ECE). Studies have shown that ECE is capable of removing, in a single application, a significant portion of the chloride ions from a reinforced concrete structure. Prior research has also shown that the quantity of chloride ions removed is dependent on numerous factors including quantity and spacing of reinforcing steel, applied voltage, initial chloride concentration, etc. In addit ion, investigations into chloride binding and competition between other ions as current carriers have helped to clarify the probable mechanisms responsible for decreases in current efficiency with time during chloride removal. This portion of the investigation has focused on the influence of water-to-cement (w/c) ratio. In addition, an investigation was conducted to identify the cause of decrease in efficiency during chloride removal. A clear relationship between the w/c ratio and the chloride extraction rate was not evident. However, the investigation revealed that the resistance of the concrete surface layer increases considerably during ECE, which effectively restricts the current flow, while the resistance of the underlying layer of concrete either decreases or remains constant. It appears that the increased resistance of the surface layer concrete is accompanied by the formation of a tightly adhering residue on the concrete surface. Preliminary analysis of the surface formation indicates it contains calcium carbonate and calcium chloride. |
| Rosap ID | dot:35821 |
| Rosap URL | https://rosap.ntl.bts.gov/view/dot/35821 |
| TRT Terms | Calcium carbonate; Calcium chloride; Cathodic protection; Chlorides; Deposition; Electrical resistivity; Electrochemical processes; Rehabilitation; Reinforced concrete bridges; Surfaces; Water cement ratio |
| General Subjects | Bridges; Electrochemical corrosion; Ions; Rehabilitation; Reinforced concrete; Restoration; Service life; Surface treatment; Efficiency; Electrochemical chloride extraction; Chloride ions; Rehabilitation of concrete bridges; Removal of chloride; Steel corrosion in concrete |
| Geographical Coverage |
United States |
| TRIS Online Accession No |
00932107 |
| Report Number | FHWA-RD-02-107; VTRC 02-R |
| Resource type | Tech Report |
| URL | https://ntlrepository.blob.core.windows.net/lib/19000/19900/19934/PB2003101517.pdf |
| Format | |
| Database | NTL Digital Repository |