Field Performance of Low-Cracking Concretes for the Closure Pours and Overlays of Bridge Decks

Abstract

Joints, wide cracks, and poor quality concretes facilitate the intrusion of chlorides, causing corrosion in bridge decks and substructures that limit the service lives. Distress in deck concretes can adversely affect ride quality and structural integrity. The objective of this study was to eliminate the joints in existing bridges and to improve the surface conditions of the decks by overlays. Two parallel bridges in Virginia were selected for study. The performance of the closure pours and overlays was observed for 4–5 years. Joints were replaced with closure pours (also known as link slabs) consisting of fiber-reinforced concretes resistant to wide cracking and intrusion of solutions. Polyvinyl alcohol, polypropylene, and steel fibers were used in the closure pours; a compressive strength of 3,000 psi (pounds per square inch) at 24 h was sought. In the overlays, silica fume concrete alone and with shrinkage reducing admixture, lightweight coarse aggregate, and lightweight fine aggregate was investigated for crack control and low permeability, and compared with the control of latex-modified concrete with rapid set cement. A compressive strength of 3,000 psi at 3 days was sought. Test results and surveys showed that satisfactory strengths and permeability were achieved; the closure pours containing steel and polyvinyl alcohol fibers had tight cracks (most less than 0.1 mm with a few up to 0.2 mm). All overlays were performing well except for one section placed in adverse weather conditions and exposed to a truck fire. There were a few areas patched where poor surface preparation had led to delamination.