Bridge deterioration requiring maintenance, repair, or replacement accounts for significant annual expenditures by state and federal transportation agencies. Concrete bridges should be designed to secure superior durability and extend service life. Greater service life is also required in repair of existing infrastructure. The use of fiber reinforcement coupled with shrinkage mitigating strategies as well as the development of adequate mixture design and construction guidelines can substantially minimize cracking, improve durability, and extend service life of concrete infrastructure. Careful design of the rheological properties of fiber-reinforced concrete (FRC) can further enhance structural performance through efficient alignment of fibers along the casting direction, resulting in substantial cost savings. The RE-CAST (Research on Concrete Applications for Sustainable Transportation) University Transportation Center led by Missouri S&T has developed fiber-reinforced concrete with adapted rheology (FRC-AR) with superior workability, cracking resistance, mechanical properties, and durability. This novel class of infrastructure material includes fiber-reinforced self-consolidating concrete (FR-SCC) for structural repair, fiber-reinforced super-workable concrete (FR-SWC) for construction of bridge sub-structural elements, thixotropic FRC for bridge deck replacement, as well as high-strength FRC (HS-FRC) for thin overlays for bridge deck rehabilitation. Limited projects implemented in Missouri, New Jersey, and Oklahoma using FRC-AC have demonstrated the superior performance of this new class of infrastructure material. The proposed pooled fund study will investigate field performance of FRC-AR under different traffic and climatic conditions to provide more substantial input to the AASHTO community for the deployment of FRC-AR for the design, construction, and rehabilitation of concrete bridges.

The primary objectives of this pooled fund study is to obtain field data and develop design provisions of fiber-reinforced concrete with adapted rheology (FRC-AR) for the design, construction, and rehabilitation of concrete bridges. In particular, the project aims to: • Investigate field performance of FRC-AR under different traffic and climatic conditions. • Develop guidelines and performance-based specifications for material and structural design and quality control testing of FRC-AR.

Scope of Work: This project will include the following 10 main tasks: 1. Propose mixture design strategies and performance-based specifications for various types of FRC-AR based on available literature. This includes the evaluation of the synergistic effect between fibers (synthetic, steel, hybrid micro and macro fibers), shrinkage mitigating strategies (shrinkage-reducing admixtures, expansive agents), and curing conditions (including internal curing). 2. Work with the technical advisory committee (TAC) comprised of pooled fund members to select candidate projects representing different traffic and climatic conditions for the use of FRC-AR. This includes FR-SCC for structural repair, FR-SWC for construction of bridge sub-structural elements, thixotropic FRC for bridge deck replacement, and HS-FRC for thin overlays for bridge deck rehabilitation. 3. Develop mixture design based on project requirements and local materials and conduct pilot testing in collaboration with different stakeholders. 4. Assess the constructability and quality of FRC-AR, including pumpability, workability and rheology, fiber alignment, and surface finish. 5. Evaluate field performance of FRC-AR using saw-cut and cored samples as well as cast-in-field samples. Of particular interest is the evaluation of the cracking resistance under different conditions (e.g., restrained shrinkage), mechanical properties (e.g., flexural strength and toughness and bond strength to substrate), and durability (e.g., corrosion resistance and frost durability). 6. Instrument and monitor the performance of various FRC-AR elements. Structural health monitoring includes embedded and remote sensors and non-destructive testing. In addition, cores will be taken from bridge elements at different intervals to evaluate permeability, chloride profile, and air void distribution for damage assessment. 7. Conduct lifecycle cost assessment of the FRC-AR for repair and construction of bridge elements subjected to different traffic and climatic conditions. 8. Prepare a final report detailing the construction efforts, test results, and implementation potential for participating states. 9. Disseminate results through workshops, publications in peer reviewed journals, and conference proceedings. 10. Propose guidelines and performance-based specifications that can be considered by the AASHTO community for FRC-AR.

The Missouri Department of Transportation (MoDOT) is seeking a minimum of six (6) partner states to commit funds in the amount of $50,000 per year for 4 years. The total funding amount per partner is $200,000. MoDOT will be the lead agency. The scope of the project is scalable based on the level of funding received.