Abstract
A corrosion assessment survey was conducted with the objective of facilitating the selection of repair methods for the corrosion control of two reinforced concrete bridges. The work completed during the evaluation consisted of visual inspections, depth of cover determinations, concrete resistivity measurements, chloride analyses, carbonation depth measurements, and cathodic protection feasibility tests. Results from preliminary field-testing indicated that these 75+ year old historically significant structures both exhibited widespread corrosion distress throughout most of the substructure components due to carbonation of the concrete matrix. These areas were generally associated with shallow concrete cover over the steel reinforcement. Consequently, the concrete resistivity values measured at the two bridges were high in comparison to resistivity values observed in various other Florida locations. Tests to assess the prospect of using cathodic protection (CP) as a means of controlling the state of corrosion were preformed using a series of zinc foil anodes with an ionically conductive adhesive backing. Results from the CP tests indicated that although anode current outputs were low, the steel was cathodicaly protected due to a rapid high potential shift observed. Based on the field results and an economic analysis, the use of a sacrificial metalized zinc CP system, applied directly unto the spalled areas, emerged as the leading restoration option.
