Project Description:

Advancements in manufacturing methods and the growing demand for high-strength materials in reinforced concrete have led to the development of steel reinforcing bars with strengths exceeding 100 ksi. These ultra-high-strength bars hold significant promise for bridge construction, as they could extend feasible span lengths beyond those achievable with conventional reinforcement while still meeting strength and serviceability requirements. Their use can also reduce girder depth, leading to material savings and lower overall construction costs. However, successful implementation requires addressing key concerns regarding serviceability and durability. Critical factors include corrosion resistance, structural behavior, and ductility of beams reinforced with these high-strength bars. 
The primary objective of the proposed work is to investigate the durability (corrosion resistance) and serviceability of concrete girders reinforced with very high-strength reinforcement, by testing bond-slip relationship between corroded and non-corroded steel rebars and concrete. 12 medium-span (8 in x 12 in x 10 ft) concrete beams will be cast and tested for strength and ductility (Figure 1). Six of the 12 beams will be subjected to accelerated corrosion. Under controlled conditions, we will test the strength and ductility characteristics of the beams reinforced with these bars. 
This study directly supports the mission of the Center for Healthy and Durable Transportation (CHDT), a University Transportation Center (UTC), whose primary research focus is enhancing the durability and service life of transportation infrastructure through innovative construction materials and techniques. By addressing the performance of very high-strength reinforcing bars in reinforced concrete girders and their behavior under corrosive conditions, this project advances the application of durable, next-generation materials for transportation infrastructure.

Figure 1. Development Length Test Setup for High-strength reinforcement

US DOT Priorities:  

This project directly advances the U.S. Department of Transportation’s priorities by promoting durability, cost efficiency, and construction effectiveness in transportation infrastructure. By investigating the corrosion resistance and bond-slip behavior of ultra-high-strength reinforcing bars in concrete girders, the research will provide critical insights into how these materials perform under corrosive conditions. This understanding will lead to improved design and material strategies that enhance structural durability, extend service life, and reduce long-term maintenance needs. The use of very high-strength reinforcement also enables the design of slimmer girders with reduced cross sections, lowering the volume of concrete and steel required. These material savings translate to lower overall construction costs, lighter structures, and reduced transportation and installation demands. Furthermore, optimized girder geometry and lighter components can improve constructability, allowing for faster fabrication, transport, and erection, ultimately enhancing construction efficiency and reducing traffic disruptions. Collectively, this project supports USDOT’s mission to develop more durable, sustainable, and cost-effective transportation infrastructure through the application of next-generation high-performance materials.

Outputs:

The outputs of this project will include new experimental data, analytical methods, and design recommendations that advance the understanding and practical application of ultra-high-strength reinforcement in concrete bridge girders. Specifically, the research will produce a comprehensive dataset on bond-slip relationships between corroded and non-corroded ultra-high-strength steel rebars and concrete, as well as detailed results on the strength, ductility, and serviceability performance of girders reinforced with these materials. These findings will contribute to the development of improved modeling techniques and design guidelines for the use of high-strength reinforcement in bridge applications.

Outcomes/Impacts:

The outputs of this research will have direct applications in improving bridge design, construction, and maintenance practices across the transportation system. The experimental data and analytical methods developed will provide the foundation for refined design guidelines and code provisions for using ultra-high-strength reinforcement in concrete bridge girders. These findings can be incorporated into updates to AASHTO and state DOT design specifications, influencing national standards and promoting the broader adoption of durable, high-performance materials in transportation infrastructure. The new bond-slip and corrosion performance data will help engineers more accurately predict service life and long-term behavior, leading to safer and more reliable bridge structures.