Alleghany County (Virginia), Bearing capacity, Bridge decks, Coarse aggregates, concrete overlays, Interstate 64, Latex modified concrete, lightweight aggregates, Silica fume
Silica fume and latex modified concrete overlays are widely used to protect bridge decks due to their low permeability. Cracking of overlays does occur, so options are desired to prevent it. In this project, silica fume concrete with shrinkage-reducing admixture, lightweight coarse aggregate and lightweight fine aggregate will be studied to determine their effect on cracking. Lightweight concrete also helps reduce dead load and can be used to rehabilitate and widen decks when the substructure has limited carrying capacity. In closure pours, fiber-reinforced concretes can be used to control cracks. The study will use three modifications of silica fume concrete in overlays. Latex modified and silica fume concrete overlays will be the controls. In closure pours, three fiber-reinforced concrete systems will be used. Rapid-set concrete with latex will be the control. Two Interstate 64 bridges over Dunlap Creek in Alleghany County - each with five simple spans - will be used for the project.