Evaluation of Surface Preparation and Bond Angle Combinations for Joint Replacement using Ultra-High Performance Concrete
Funderburg, Chandler K.
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Deterioration of bridges is often attributed to declining performance of the longitudinal connections between precast members or transverse deck joints. Ultra-high performance concrete (UHPC) is a cementitious composite with mechanical and durability properties far exceeding those of conventional concrete, making it an ideal material for bridge deck joints. This project included a multi-faceted evaluation of the proprietary UHPC material, Lafarge Ductal®, to determine best practices for placing UHPC joints and to better understand their behavior. Composite modulus of rupture (MOR) specimens were tested in flexure to determine the effects of varying interface angles and levels of surface roughness on bond strength. Slant shear tests were performed on composite cylinders to provide a baseline of bond strength with no surface manipulation. Static and fatigue flexural testing was performed on three medium-scale slabs with heat cured UHPC joints to determine their flexural capacity and the effects of cyclic loading on the joint interface. The MOR specimens exceed the flexural strength of the base concrete, and most did not experience interface failure. Two slabs, tested statically in flexure, had experimental capacities exceeding the estimated capacity. The third slab, loaded cyclically, achieved 3 million cycles of a load less than the cracking load and experienced degradation in performance. It then failed at a much lower number of cycles after the load was increased. These results indicate that UHPC provides superior structural performance for slab joints and is worth studying further in future research.
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