Repair/Preservation of Concrete Compression Members in Bridges Using Ultra-High-Performance Concrete (UHPC)

As of 2024, approximately 36% of bridges across the United States require repair or replacement, with 7% classified as structurally deficient. The estimated cost to address these deficiencies exceeds $260 billion. In recent years, Ultra-High-Performance Concrete (UHPC) has emerged as a repair material for infrastructure preservation, drawing increased attention from transportation agencies and researchers worldwide. The Federal Highway Administration (FHWA) has notably advocated for UHPC’s adoption in bridge preservation initiatives, recognizing its exceptional mechanical properties and durability. This report presents a comprehensive literature review on the application of UHPC as a repair and strengthening material for bridge compression members. While significant progress has been made in employing UHPC for bridge decks and joints, its use in repair or strengthening bridge columns/piles remains relatively underexplored. To address this gap, the study introduces an analytical model designed to predict the axial and flexural capacities of reinforced or prestressed concrete compression members encased with UHPC jackets. The model is formulated based on strain compatibility and integrates idealized UHPC material behavior in both tension and compression, consistent with the latest UHPC design specifications. In addition, an experimental program was conducted to evaluate the structural benefits of UHPC encasement in compression members. The investigation consisted of two phases. Phase I assessed the confinement effect of UHPC on small-scale concrete cylinders with varying jacket thicknesses, revealing notable enhancements in compressive strength and ductility. Phase II focused on full-scale reinforced concrete columns subjected to axial loading and bending, examining the bond behavior at the UHPC–conventional concrete (CC) substrate interface under different surface preparation methods and the influence of transverse reinforcement within the UHPC jacket. Results confirmed a strong interfacial bond and underscored the role of transverse reinforcement in delaying failure and improving overall structural performance. The report concludes with a detailed design example, demonstrating the model’s applicability and its predictive accuracy in estimating strength gains due to UHPC jacketing. Collectively, this study provides both a practical design framework and novel experimental insights, reinforcing UHPC’s potential to enhance structural performance and extend the service life of aging bridge infrastructure.