Chloride Testing of 27-Vear-Old Prestressed Concrete Bridge Beams

Abstract

This paper discusses chloride testing that was done on five 27-year-old prestressed concrete box beams, 36 in. wide x 27 in. deep (914 x 686 mm), removed from a deteriorated, 54 ft (16.5 m) span multibeam bridge in Connecticut. Limited half-cell testing was also done. Generally, samples from midwidth of the top flanges had low chloride concentrations on the side faces, probably due to water seeping through the grouted shear keys. Some concrete samples had chloride concentrations two to three times the corrosion threshhold level; many other samples had low chloride concentrations. The edge beam, which carried a cast-in-place sidewalk, had chloride concentrations above the corrosion threshold level to a depth of 8 in. (200 mm) below the top surface of the sidewalk. Several locations had chloride concentrations that increased with depth from the surface.