Bonded Concrete Overlays

Laboratory tests to evaluate the bond between freshly overlaid concrete on an existing concrete surface were studied. Cement grout and epoxy were used separately as bonding agents on two parallel series of tests with preparation of existing surface as a variable. Static and repeated loadings were applied on freshly overlaid precracked concrete beams. The contribution of the bonded concrete overlay to the flexural rigidity of the beam at various stages of loading were determined. It was concluded that concrete overlays can be made to bond to existing concrete surfaces using cement grout or epoxy as bonding agents, and that repeated loadings within the working range will not cause bond failure between the two concretes. Thin bonded concrete overlays were found to increase considerably the flexural rigidity and the ultimate moment capacity of the existing concrete section.