Evaluation of Functionality and Service Life of Ultra-High Performance Concrete Link Slab Connections for Bridges

Abstract

Structural longevity and sustainability are rising priorities in bridge construction. Accelerated bridge construction is a response to such a demand, with a goal of providing bridges with a longer service life in a construction process more time and cost effective. Link slabs have been an attractive alternative to expansion joints by providing protection for rebar and underlying reinforcement from contaminant exposure. Though traditionally constructed with conventional concrete, there is a growing interest in ultra-high performance concrete (UHPC) in bridge construction due to its higher strength and durability. Utilizing UHPC in link slabs has the potential to further extend the service life of these connections and mitigate the frequency of costly repairs and replacements. Using a non-proprietary UHPC mix developed at the University of Oklahoma, labeled “J3,” this research investigated its performance as a link slab construction material. The UHPC’s performance was compared to Class AA concrete, the Oklahoma Department of Transportation (ODOT) conventional mix standard for bridge construction. Both materials were used in constructing link slab specimens, with segments of these specimens subjected to durability and corrosion tests. A link slab of each concrete mix experienced cyclic loading prior to segmentation and durability testing. This provided insight to how in-service loading may affect the connection’s performance compared to a newly-constructed link slab. Tests conducted included rapid freeze-thaw cycling and accelerated corrosion testing. UHPC specimens, pre-loaded or not, resisted loss of strength after 350 freeze-thaw cycles better than conventional concrete. Loading did slightly influence the UHPC mix’s performance but had a greater impact on the performance of the Class AA mix. Corrosion observations show the effects of testing were significantly more severe for conventional concrete. UHPC results are far more promising, with prior loading conditions having virtually no influence on these results. Overall, UHPC proved to be a superior construction material for link slabs by providing greater resistance to temperature effects and greater protection for reinforcement, offering a longer service life with fewer repairs.