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Nebraska Precast Concrete Pavement

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A presentation given during the 39th Annual NCPA Concrete Paving Workshop. By Samuel Tyson, P.E., Federal Highway Administration

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Nebraska Precast Concrete Pavement

  1. 1. Precast Concrete for Rapid Repair and Rehabilitation of High Traffic-Volume Concrete and Asphalt Pavements 39th Annual Concrete Paving Workshop January 16-17, 2018 Lincoln, Nebraska Samuel Tyson, P.E. Federal Highway Administration Washington, District of Columbia
  2. 2. Precast Concrete Pavement (PCP) • High Traffic Volumes • Alternate Route Availability • Rapid Renewal • Lane-Closure Times • Work-Zone Safety • Opening to Traffic • Concrete Quality • Long-Life Performance
  3. 3. Highway Agencies in USA Used PCP PCP in Progress
  4. 4. Reinforcement & Prestressing • Nominal reinforcement (0.12-0.15 %) for handling stresses & to control potential cracking. • Pre-tensioning by fabricator allows reduced panel thickness. • Pre-tensioning also for wider and longer panels (e.g., two-lane width). • Post-tensioning applied on site to connect a series of panels.
  5. 5. Bedding Support for PCP Systems Uniform support key to PCP performance • Existing base graded and compacted • New base material • Cement-treated • Rapid-setting lean concrete • Undersealing • Rapid-setting grout • Polyurethane
  6. 6. Base Preparation & Panel Leveling • Trimming of Stabilized Base – Time- consuming activity. • Thin Shims – Typically requires lifting of panels to adjust shims. • Polyurethane Foam Injection – Specialized equipment required. • Fast-Setting Lean Concrete – Partial removal of base and screeding. • Leveling Bolts – Rapid and accurate.
  7. 7. Trimmed base with 0.5-inch (12-mm) bedding layer of cemented fine-grained granular material
  8. 8. Typical Leveling Bolts
  9. 9. Leveling Bolt & Grout Ports During Concrete Placement
  10. 10. Panel-to-Base Contact • Panels Installed Directly on Base –Grout injected through ports to fill any voids. –Panel raised to grade by injection of polyurethane foam. • Panels Installed with Leveling Bolts –Grout fills 0.5-in. (12 mm) gap between bottom of panel and base.
  11. 11. Load Transfer Slots & Dowels for Jointed PCP Systems
  12. 12. • Repair Applications o Nominally reinforced panels routinely used o Pre-tensioned panels if longer/wider dimensions • Continuous Applications o Jointed PCP systems  Nominally reinforced  Pre-tensioned panels o Post-tensioned systems  Nominally reinforced panels  Pre-tensioned panels  Fewer active joints and longer sections PCP Applications
  13. 13. PCP Applications (continued) • Repair Applications –Service-life of 15 to 20 years is predicted for PCP repairs. –Existing pavement may need to be reconstructed prior to 15 years. –Exceeds 8 to 10 years experienced with rapid-hardening concretes.
  14. 14. Single Panel for Full-Depth Repair Dowels for Load Transfer
  15. 15. PCP Applications (continued) • Continuous Applications –Service-life of 40+ years. –No early failures or materials- related distress. –Reduced potential for cracking, faulting & spalling. –Smoothness and surface texture initially good & easily maintained.
  16. 16. Rapid Replacement of Rutted Asphalt Ramp.
  17. 17. Continuous Applications – Dowel slots top/bottom for load transfer Jointed
  18. 18. Continuous Application – Post-tensioned
  19. 19. Typical Uses/Nighttime Work • Principal Uses oHeavily-traveled interstate and primary roadways – Critical need in all States. oInterstate and urban ramps – Often no convenient alternate routes. • Special Uses oIntersections – Traffic delays minimized. oBridge approaches – Smooth transition from pavement to bridge. oBus pads – Avoid disruption of service. oAirfields – A developing application.
  20. 20. Delaware DOT – Outside Lane and Shoulder/Right-Turn Lane Left-Turn Lane
  21. 21. Virginia DOT – 3 Lanes and Outside Shoulder/Rush- Hour Lane
  22. 22. Virginia DOT – Outside Lane of Exit Ramp
  23. 23. Hawaii DOT – Full-Depth Repair of 5 Lanes and Outside Shoulder/Right- Turn Lane
  24. 24. Texas DOT – Reconstruction of Industrial Intersection in Energy Sector
  25. 25. Surface Finishing • Vertical tolerances with routine leveling methods may or may not be satisfactory for high-speed roadways. • Grinding may be needed for smoothness due to vertical differences at transverse joints. • Smoothness and surface texture achieved on-site with grinding.
  26. 26. • Panel fabrication rate – –Inside plant; 10 panels/day. –Pre-stressing bed; 30 panels/day. • Panel installation rate – –Repair; 20 panels/night. –Continuous; 50 panels/night. • Inventory – Several weeks (or months) of panel production is needed before installation on project can begin. Panel Fabrication/Installation Rates
  27. 27. Precast Panel Fabrication Outdoor Prestressing Bed for Multiple Panel Production Typical Reinforced Panel Production
  28. 28. • Experience in the USA with PCP systems is limited to 16 years. • PCP systems are rapidly installed. • PCP systems provide long-term performance following satisfactory design, fabrication and installation. • Fabricators & contractors having no prior experience are producing and installing panels satisfactorily. Summary

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