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A platform for research: civil engineering, architecture and urbanism
Characterization of Chloride Thresholds in Florida Coastal Concrete Bridge Substructures
Sea water induced reinforcing steel corrosion often results in high maintenance costs and can be service life limiting for concrete bridge substructure elements in marine environments. In the present research, a novel piling type specimen assembly and test protocol were developed to simulate performance of actual substructure elements undergoing marine exposure. Specimen mix design was based on the mortar component of a FDOT Class V high performance concrete, both with and without fly ash. The relatively low diffusion coefficient for such mixes and the long time that normally would be required for corrosion initiation was offset by employing covers of 12 mm for the non-fly ash mortar and 8 mm for the fly ash one. Exposures involved partial submergence in 15 wt% NaCl and in some cases periodic spraying of the above waterline zone to simulate splash. The rebar of some sprayed specimens was connected to submerged bare steel such that the lower portion of the simulated piling rebar was cathodically polarized, and it is demonstrated that the resultant potential profile was similar to that of actual marine pilings for which reinforcement below the waterline also exhibits a relatively negative potential because of oxygen concentration polarization. Consequently, the above waterline (splash) zone of the present specimens was cathodically polarized similar to what occurs in actual structures. Times to corrosion for the specimens were approximately the same for sprayed and unsprayed specimens but were greater for sprayed and polarized ones. In some cases, corrosion initiated above the waterline for sprayed and sprayed and polarized specimens, as typically occurs in actual bridge substructure elements.
Characterization of Chloride Thresholds in Florida Coastal Concrete Bridge Substructures
Sea water induced reinforcing steel corrosion often results in high maintenance costs and can be service life limiting for concrete bridge substructure elements in marine environments. In the present research, a novel piling type specimen assembly and test protocol were developed to simulate performance of actual substructure elements undergoing marine exposure. Specimen mix design was based on the mortar component of a FDOT Class V high performance concrete, both with and without fly ash. The relatively low diffusion coefficient for such mixes and the long time that normally would be required for corrosion initiation was offset by employing covers of 12 mm for the non-fly ash mortar and 8 mm for the fly ash one. Exposures involved partial submergence in 15 wt% NaCl and in some cases periodic spraying of the above waterline zone to simulate splash. The rebar of some sprayed specimens was connected to submerged bare steel such that the lower portion of the simulated piling rebar was cathodically polarized, and it is demonstrated that the resultant potential profile was similar to that of actual marine pilings for which reinforcement below the waterline also exhibits a relatively negative potential because of oxygen concentration polarization. Consequently, the above waterline (splash) zone of the present specimens was cathodically polarized similar to what occurs in actual structures. Times to corrosion for the specimens were approximately the same for sprayed and unsprayed specimens but were greater for sprayed and polarized ones. In some cases, corrosion initiated above the waterline for sprayed and sprayed and polarized specimens, as typically occurs in actual bridge substructure elements.
Characterization of Chloride Thresholds in Florida Coastal Concrete Bridge Substructures
F. Presuel-Moreno (author) / W. H. Hartt (author) / R. Tanner (author)
2009
121 pages
Report
No indication
English
Highway Engineering , Construction Equipment, Materials, & Supplies , Corrosion & Corrosion Inhibition , Reinforced concrete , Corrosion , Corrosion testing , Chloride threshold , Sea water , Concrete durability , Bridge maintenance , Figures , Tables , Mix designs , Specimen geometry , Experimental procedures , Florida , Steel reinforcements , Characteristics , Chloride thresholds , Bridge substructures , Reinforcing steels , Sea water induced reinforcing steel corrosion
Concrete in bridge substructures
Engineering Index Backfile | 1922
Seismic Rehabilitation of Concrete Bridge Substructures
| British Library Conference Proceedings | 1996
Cathodic Protection of concrete bridge substructures
| TIBKAT | 1985
Cathodic Protection of Concrete Bridge Substructures
| NTIS | 1985
Survey of Concrete Deterioration in Bridge Substructures
| NTIS | 1983