Low-cycle fatigue testing of high-performance concrete bonded overlay-bridge deck slab systems

Plain and fibrous latex modified concrete and microsilica concrete overlays with acceptable laboratory strength and durability characteristics were installed on a full-scale prototype bridge deck for field performance evaluation. After I year of exposure to drying shrinkage, temperature variations, and freeze-thaw cycles, no cracking or debonding were observed in the overlays. The bond strengths at 28 days and at I year were acceptable for all overlay types due to the excellent curing and surface preparation using water-jet blasting. The prototype bridge was then statically tested before and after applying low-cycle fatigue loading simulating AASHTO HS20 truck service load, overload, and ultimate load. Minor bond strength deterioration at the maximum negative moment region and slight bridge stiffness degradation were observed after each load case. Significant enhancement in the bridge stiffness was observed after installation of the overlays. Also, the overlay with synthetic fibers showed better crack bridging action than the overlay with steel fibers.