Bond characterization of UHPC overlays for concrete bridge decks: Laboratory and field testing

This paper aims to characterize the bond behavior and performance of UHPC-class materials as overlays on bridge deck concrete substrates. The study includes laboratory testing, field testing, and microstructural analysis using scanning electron microscopy (SEM). The laboratory portion examines the direct tension bond strength between UHPC and substrate concrete with different substrate surface preparations; namely, hydrodemolition and scarification. The field testing examines the tensile bond strength of the first UHPC bridge deck overlay in the United States. Lastly, microstructural analysis is used to investigate consolidation of the overlays, the substrate surface condition, and the hydration products and porosity at the interface between the overlay and substrate. The paper discusses correlation between bond strength and consolidation, mechanical interlock, chemical bond, and substrate surface condition and preparation. Published by Elsevier Ltd.