FHWA High Performance Concrete Research Program Dr. Benjamin Graybeal, P.E. Lou Triandafilou, P.E.

1. FHWAHigh Performance Concrete Research ProgramDr. Benjamin Graybeal, P.E.Lou Triandafilou, P.E. Turner-Fairbank Highway Research Center Federal Highway Administration

2. FHWA HPC Program • Section 5202(b)(3)(B) of SAFETEA-LU • RT&E on HPC bridges • Fiscal 2006 through 2009 • ≈ $2.9M per year after adjustments, etc. • R&D at TFHRC • D&D at Headquarters • TT through Resource Center

3. FHWA HPC Research Program • FHWA “Bridge of the Future” initiative • 100-year service live w/ little or no maintenance • Significantly reduced construction time • Easily widened or adapted to new demands • Significantly reduced life-cycle cost • Significantly improved resistance to typical and extreme natural and man-made hazards • Integrated substructure and superstructure design and construction • Elimination of vertical and lateral clearance problems

4. FHWA HPC Research Program • Program developed by FHWA in consultation with stakeholders and industry • Primary topics to be addressed • Lightweight Structural Concrete • Shear of Non-Prestressed Elements • HPC Deck Behavior (Cracking, Durability, etc.) • NDE Methods for Void Detection in PT Ducts

5. Lightweight Structural Concrete • AASHTO LRFD allows lightweight • Includes arbitrary definitions • Based on dated research from a limited compressive strength range

6. Lightweight Structural Concrete • NCHRP 18-15 • Parallel effort ongoing with proposals due today • Effort focused on equilibrium densities less than 125 pcf • RFP focused on material characterization with limited structural testing for verification of behaviors

7. Lightweight Structural Concrete • Research Objective • Address perceived shortcomings in LRFD with regard to equilibrium densities less than 140 pcf • Are across-the-board resistance factor modifications correct? • Are predictor equations acceptably accurate? • What about equilibrium densities between ‘normal weight’ and ‘sand lightweight’?

8. Lightweight Structural Concrete • Focal Areas • Structural behavior research focusing on higher strength girders and higher durability decks • Material characterization research focusing on strength, serviceability, stability, and production issues

9. Lightweight Structural Concrete • First Steps • Synthesis of existing research results and the state-of-the-practice regarding the use of lightweight concrete in highway bridges • Currently underway • Scheduled for completion in January 2007

10. Lightweight Structural Concrete • Phase 1: Material Property Characterization of Structural Lightweight Concrete • Literature Search • Identification of Mix Designs • Range of equilibrium densities • Range of lightweight coarse aggregates • Mixes representative of normal/intended use • At least 3 mixes for superstructures • At least 3 mixes for decks

11. Lightweight Structural Concrete • Phase 1: Material Property Characterization of Structural Lightweight Concrete (continued) • Test Program • Strength (Compressive, Tensile, Modulus) • Stability (Creep, Shrinkage, CTE) • Durability (Freeze-Thaw, Scaling, Chloride Pen) • Compile Results • Develop predictor equations • Prepare final report

12. Lightweight Structural Concrete • Phase 2: Behavior of Structural Lightweight Concrete Bridge Components • Literature Search • Identification of Mix Designs • Use mix designs from Phase 1

13. Lightweight Structural Concrete • Phase 2: Behavior of Structural Lightweight Concrete Bridge Components (continued) • Test Program • Shear capacity in superstructure members • Transfer and development length of strands • Development length of rebar • Prestress losses • Confinement requirements for anchorage regions • Punching shear capacity

14. Lightweight Structural Concrete • Phase 2: Behavior of Structural Lightweight Concrete Bridge Components (continued) • Test Program (continued) • Testing completed on full-scale components • Compile Results • Develop predictor equations for relevant behaviors • Prepare final report

15. Shear Capacity of Non-Prestressed High-Strength Concrete Members • AASHTO LRFD Shear Provisions • High-strength concrete use restricted to situations where physical tests have demonstrated applicability of relationships • NCHRP 12-56 focused heavily on prestressed girders • Other members composed of HSC have not been thoroughly addressed

16. Shear Capacity of Non-Prestressed High-Strength Concrete Members • Research Objective • Extend applicability of shear provisions for normal weight concrete to 18 ksi compressive strength without any restriction on structural applications

17. Shear Capacity of Non-Prestressed High-Strength Concrete Members • Research Plan • Perform literature search for relevant prior work • Develop practical HPC mix designs with the desired properties • Perform full-scale component tests to determine the relevant behaviors • Report results

18. HPC Deck Behavior • HPC Deck Issues • HPC deck cracking is an ongoing concern • Early age and longer term behaviors • HPC may exacerbate issues due to potential higher strengths & stiffnesses • Mix designs, construction practices, lack of oversight, etc. may all be underlying causes

19. HPC Deck Behavior • Research Objective • Identify the primary root causes of underperformance of HPC bridge decks • Develop and/or verify remedies National focus … range of issues and solutions

20. HPC Deck Behavior • Research Plan • Compile experiences and best practices from around the U.S. • Establish, verify, develop, and/or compile: • good mix designs • effective construction practices (e.g., curing duration and equipment, limiting weather factors) • Perform full-scale laboratory testing as necessary • Report findings and disseminate results

21. NDE Methods for Detecting Voids in Post-Tensioning Ducts • Strand Deterioration Resulting from Voids • Detailing and construction practices can lead to voids in tendon ducts • Voids already exist due to past practices • Future voids are likely even with better detailing and better construction practices • Locating voids can allow for remediation prior to strand deterioration

22. NDE Methods for Detecting Voids in Post-Tensioning Ducts • Research Plan • Synthesize existing practice and recent research regarding void and deteriorated strand detection • Compile a state-of-the-research report • Develop experimental research plan based on synthesis results and availability of funds