Fiber-Reinforced Concrete in Closure Pours over Piers

Cracks in concrete, high permeability, or leaking bridge joints facilitate the penetration of chloride solutions, resulting in extensive corrosion damage. Joints can be eliminated by constructing continuous decks or closure pours, and infiltration through concrete can be minimized by using low-permeability concrete and fiber-reinforced concrete (FRC) that controls cracks. This study investigated low-permeability FRCs with polyvinyl alcohol (PVA), polypropylene (PP), or steel (S) fibers to control cracking in closure pours. Large volumes of suitable fibers used in FRC enable high residual strengths and deflection hardening behavior. Generally, in these concretes, multiple tight cracks (less than 0.004 in. [0.1 mm] wide) occur, which resist the ingress of harmful solutions. In two bridges on I-64 near Covington, VA, closure pours with FRCs were placed. The initial results indicate, in general, no or tight cracking in FRCs with PVA, PP, or S fibers. Deflection hardening did not occur in all mixtures; however, the tight cracks observed were attributed to the addition of fibers and the presence of primary reinforcement.