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Concrete Overlays: A Proven Resurfacing Strategy

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Gordon Smith, PE

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Concrete Overlays: A Proven Resurfacing Strategy

  1. 1. CONCRETE OVERLAYS A PROVEN RESURFACING STRATEGY Gordon Smith, P.E., Associate Director National CP Tech Center
  2. 2. 40th Annual Concrete Paving Workshop January 22, 2019 Lincoln, Nebraska
  3. 3. Highway agencies and industry are responding with new ideas about building and modernizing today’s pavement networks. CHANGE IS ALL AROUND US
  4. 4. NEW LIFE FOR AGING PAVEMENTS
  5. 5. Preservation Resurfacing Overlays Reconstruction Preservation Mode!Preservation Mode! $ $
  6. 6. SO, WHAT ARE WE DOING ABOUT IT? WE’RE WORKING IN PARTNERSHIP TO DEVELOP STRATEGIES AND GUIDELINES FOR PROJECT SPECIFIC, COST EFFECTIVE CONCRETE SOLUTIONS.
  7. 7. CONCRETE OVERLAYS FOR EVERY NEED! .. ...... .. ...... .... .. .. .... .. .... .... .... .. .. .. ...... .. ..
  8. 8. WT BOL UBOL Secondary 1177.6 88.4 490.5 1756.5 Primary 81.8 52.7 160.7 295.2 1259.4 141.1 651.2 2051.7 miles Municipal 300,000 SY (approximate) Airport 739,840 SY (24 Runways)
  9. 9. CONTENTS 1. Overview of Overlay Families 2. Overlay Types and Uses 3. Evaluations & Selections 4. Six Overlay Summaries (11”x17 “sheets) 5. Design Section 6. Miscellaneous Design Details 7. Overlay Materials Section 8. Work Zones Under Traffic 9. Key Points for Overlay Construction 10. Accelerated Construction 11. Specification Considerations 12. Repairs of Overlays
  10. 10. CONCRETE OVERLAYS Bonded Concrete Overlay of Concrete Pavements Bonded Concrete Overlay of Asphalt Pavements Bonded Concrete Overlay of Composite Pavements Bonded Overlay System Unbonded Concrete Overlay of Concrete Pavements Unbonded Concrete Overlay of Asphalt Pavements Unbonded Concrete Overlay of Composite Pavements Unbonded Overlay System Thinner Thicker BOND IS INTEGRAL TO DESIGN OLD PAVEMENT IS BASE
  11. 11.  Not a new design procedure!  Background of recommended overlay design techniques  Detailed examples of how to use the existing design methodology  Learn by example – then apply for your situation!  http://www.cptechcenter.org
  12. 12. Check Out PavementDesigner Pavement Design Simplified for:• Streets and Roads • JPCP • RCC • CRCP • Overlays • Parking Facilities • Intermodal Yards FREE Pavement Design Program
  13. 13. NATIONWIDE CONCRETE OVERLAYS GROWTH As of: November 2017
  14. 14. CONCRETE OVERLAYS IN THE USA  National perspective  ACPA overlay project explorer:
  15. 15. IOWA’S HISTORY OF CONCRETE OVERLAY PERFORMANCE
  16. 16. ACKNOWLEDGEMENTS  Full Report: Performance of Concrete Overlays in Iowa  Phase I of Iowa Highway Research Board TR-689  Project Team:  CP Tech Center: Jerod Gross, Dale Harrington, Dr. Peter Taylor  Iowa State University: Yu-An Chen, Dr. Halil Ceylan, Inya Nnelanya, Dr. Omar Smadi
  17. 17. CONCRETE OVERLAYS IN IOWA  Iowa: over 2,000 centerline miles of concrete overlays have been constructed since the late ‘70s  Over half constructed since 2005  Mostly on county highway system
  18. 18. PROJECT BACKGROUND  How well have Iowa’s overlays performed? (How long do they last?)  Approximately 470/506 overlay projects are still in service today  Includes 68/96 constructed before 1990  Compare to older sources that indicate expected service life for a concrete overlay is only about 20 years Dallas County, IA, Constructed 1977
  19. 19. PROJECT BACKGROUND  However, as of 2015, there had been no attempt to characterize performance of overlays to determine expected service life & what made projects successful Dallas County, IA, Constructed 1992
  20. 20. PROJECT OBJECTIVES  Define performance of Iowa’s concrete overlays  Create performance curves  Analyze specific design choices and characteristics and link to performance  Overlay type (thin bonded, unbonded)  Thickness  Joint spacing  Traffic  Incorporate lessons learned to improve overlay design and performance
  21. 21. DATA COMPILATION & COLLECTION  Automated pavement condition data: Iowa Pavement Management Program (IPMP)  Opt-in program for local agencies  Data collection began in early 2000s (opt-in)  Since 2013, all streets & roads are covered every other year  This data then combined with ICPA overlay project records to produce the complete data set
  22. 22. OVERLAY TYPES  Bonded Concrete Overlay of Concrete (BCOC)  Bonded Concrete Overlay of Asphalt (BCOA)  Defined as thickness ≤ 6 inches  Unbonded Concrete Overlay of Concrete (UBCOC)  Unbonded Concrete Overlay of Asphalt (UBCOA)  Defined as thickness > 6 inches
  23. 23. DATA DISTRIBUTION  Typical designs in Iowa  Early on: 6 inches on asphalt (“whitetopping”) or 6+ inches unbonded on concrete  Performance data for projects up to 40 years old Washington County, IA, Constructed 1977
  24. 24. DATA DISTRIBUTION  Typical designs in Iowa  ‘00s: more types of projects, including thinner overlays  Advent of new design procedures, shorter slabs, fiber-reinforcement  About 10 years worth of data, with some exceptions Boone, IA, Constructed 2005
  25. 25. DATA DISTRIBUTION  Full data set contains all overlay types/designs:
  26. 26. 36
  27. 27. DATA DISTRIBUTION  Distribution based on slab thickness:
  28. 28. 38
  29. 29. 39
  30. 30. PERFORMANCE METRICS  Performance characterized by PCI (Pavement Condition Index) & IRI  IPMP PCI equation incorporates:  IRI (accounts for 40% of PCI)  Transverse Cracking  Joint Spalling  D-cracking (no faulting) Le Mars, IA, Constructed 2010
  31. 31. PERFORMANCE METRICS  Performance charts:  PCI scale:  Excellent: 81-100  Good: 61-80  Fair: 41-60  Poor: 21-40  Very Poor: 0-20 Image: Pavement Interactive
  32. 32. RESULTS AND ANALYSIS  PCI vs. Age (data set as a whole): Figures: Chen and Ceylan
  33. 33. PCC OVERLAY PERFORMANCE PCI (Ages 0-37 years)
  34. 34. PCI (Ages 21-30 years) 44
  35. 35. RESULTS AND ANALYSIS  PCI vs. Age - BCOA only (organized by thickness): Figures: Chen and Ceylan
  36. 36. RESULTS AND ANALYSIS  PCI vs. Age - BCOA only (organized by joint spacing): Figures: Chen and Ceylan Short slab designs
  37. 37. RESULTS AND ANALYSIS  PCI vs. Age - UBCOA only (organized by thickness): Figures: Chen and Ceylan
  38. 38. RESULTS AND ANALYSIS  PCI vs. Age - UBCOC only (organized by thickness): Figures: Chen and Ceylan
  39. 39. RESULTS AND ANALYSIS  IRI vs. Age (data set as a whole): Figures: Chen and Ceylan ~40 years to IRI = 170
  40. 40. 50 PCC OVERLAY PERFORMANCE IRI (Ages 0-37 years)
  41. 41. IRI (Ages > 30 years) 51
  42. 42. RESULTS AND ANALYSIS  Key findings and trends:  Overall performance of Iowa’s concrete overlays has been excellent  As a whole: about 35 years to PCI = 60  About 40 years to IRI = 170 in/mi  Good performance from each of BCOA, UBCOA & UBCOC  Overlays of asphalt slightly better than UBCOC  BCOC less successful overall, but performed well in context of design life expectations
  43. 43. RESULTS AND ANALYSIS  Key findings and trends:  Thickness  In general: thicker overlays have performed better for all overlay types (e.g. for BCOA, 6” > 5” > 4”)  Transverse joint spacing  Good early performance from short slab designs (6”) on BCOA/thin overlays  Older designs with 15-20 foot slabs performed well long-term  12 foot slabs—inconclusive  Traffic—inconclusive  Most of these projects are low-volume, <1,000 vpd  Not enough truck traffic data available from local agencies
  44. 44. RESULTS AND ANALYSIS  12 foot transverse joint spacing  Across multiple splits, apparent decline in performance of overlays with 12 foot joint spacing (even compared to longer spacings)  UBCOA (organized by joint spacing): Figures: Chen and Ceylan
  45. 45. FIELD REVIEWS  Field reviews were performed to:  supplement data analysis  verify findings  investigate trends, outliers Pottawattamie County, IA, Constructed 1993
  46. 46. FIELD REVIEWS  Observed distresses:  Materials-related Pottawattamie County, IA, Constructed 1999
  47. 47. FIELD REVIEWS  Observed distresses:  Rough ride—construction or curling/warping  Occasional faulting Buchanan County, IA, Constructed 1996
  48. 48. FIELD REVIEWS  Observed distresses:  Load-related, possibly mis-designed or under-designed Dallas County, IA, Constructed 2006
  49. 49. FIELD REVIEWS  Key takeaways:  Observed performance generally matches data  Poor performing outliers & early failure causes:  Materials-related  Load-related/under-design  Rough ride  In short... mostly the same issues that we run into with conventional PCC pavements  Be aware of increased potential for curling/warping  Beyond above explanations, no direct observations to indicate that there’s a specific problem with 12 ft joint spacing design
  50. 50. CONCLUSIONS  Overall performance of Iowa’s concrete overlays has been excellent  Upwards of 30-40+ year performance life  Overlays are very well-suited to county highways  Good success to date on interstate, state highways, and city streets as well
  51. 51. NEXT STEPS  Move from performance history → survivability, performance models  Continue compiling data, keeping the database updated Le Mars, IA, Constructed 2017
  52. 52. CONCRETE OVERLAY ON AN ASPHALT MUNICIPAL STREET IN LOMBARD, IL (2003)
  53. 53. I-70 @ GRAND JUNCTION, CO.
  54. 54. RURAL ROAD IN MITCHELL COUNTY, IOWA
  55. 55. NORTHBOUND US 81 NEAR STRANG AND BELVEDERE, NE 8” UNBONDED PCC OVERLAY (1982 AND 1984) 65
  56. 56. US 30 BETWEEN LEXINGTON AND COZAD, NE 5” UNBONDED OVERLAY OVER ASPHALT OVER OLD PCC (2015) 66
  57. 57. A 6-INCH UNBONDED OVERLAY OVER FULL-DEPTH HMA PLACED IN 2010 IN PIERCE COUNTY ON 556TH STREET JUST NORTH OF NORFOLK, NEBRASKA 67
  58. 58. CELEBRATING 50 YEARS OF LEADERSHIP AND SERVICECELEBRATING 50 YEARS OF LEADERSHIP AND SERVICE I-70I-70 Western KansasWestern Kansas 6x6x6 Concrete Overlay6x6x6 Concrete Overlay THIS ISTHIS IS RESURFACING!RESURFACING!
  59. 59. Grundy County, IA, Constructed 1978 www.cptechcenter.org

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