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Longitudinal Joints in Asphalt         Pavements    37th Annual Utah Asphalt Conference                   March 27, 2012  ...
Acknowledgements• FHWA and Asphalt Institute Partner to  Identity Best Practices for Longitudinal  Joints. Training Class,...
Best Practices forSpecifying and Constructing HMA Longitudinal JointsA Cooperative Effort between  Asphalt Institute & FHWA
Definitions• Longitudinal Joint – HMA placed adjacent  to existing lane, Interface between two  existing HMA mats.• Hot Jo...
Is It a Problem?
An Agency and                        Industry ConcernLongevity matters, it impacts:         LCC         Alternate Bid Co...
Project Team– Asphalt Institute   • Mark Buncher   • Carlos Rosenberger   • AI Regional Engineers– FHWA   • Thomas Harman ...
How many State Agencies havea longitudinal joint specification?  A •About third  B •About half  C •About two-thirds
Takeaways from FHWA Survey to        52 Division Offices• ½ States are not satisfied with  overall performance of L-Joints...
GETTING STARTED OFF RIGHT     Plant           Paving                                      3                               ...
Managing Material in the HopperConveyor area is exposed and augers are starved!
Tack CoatFull width of mat tominimize movement ofunsupported edge
Dump Person
First Pass Must Be Straight!Unanimous that a string-line should be used to assure first                     pass is straig...
Great Results
Paver operator usingthe curb as his reference
Tough to get proper overlap (1”)        with next pass
Use Automatic                          Control                         SystemsContact Grade Sensor                       U...
Vibratory Screed Should Always Be On
Achieving Pre-Compaction                     Screed Weight                                       Forward Motion        Vib...
END GATESeated on the ExistingSurface
Auger                        Uniform Head of Material                        Across the Entire ScreedCarry Material Within...
Another example ofuniform head ofmaterial
Hydraulic Extending Tunnels     Controlling material flow at     outer edges of screed and    delivering homogenous HMA   ...
Result of uniform head of HMAand auger/tunnel within 12 to18-inches of end gate: non-segregated HMA at the joint
Auger Overload…these areunacceptable
Auger not extended towithin 12 to 18-inchesof the end gate.The result -SEGREGATION at joint
Rollers Need to Be Kept Close to the Paver     Critical in cool and cold weather!
Our Recommendation:1st Roller Pass Hangs Over 4-6 inches
Alternative: Stay Back 4-6 incheson 1st pass, then roll 2nd pass w/         slight overhang                    • Concern: ...
What We Don’t Want         Rolling Unsupported Edge            (First Paver Pass) Edge of drum inside unsupported edge   c...
Compacting Notched Wedgeadd-on vibratory compactor                             plate compactor
Quality Control, Monitor Joint Density
Tack the Joint! (Butt or Wedge)      Emulsion, orGood, Better, Best         PG asphalt or                           Propri...
Paver Automation Using Joint Matcher(versus Ski) to Always Achieve Exact      Thickness of Mat NeededIf the joint (hot-sid...
Destined for               Hot side of jointFailure        starved of material.               Bridging?
Types of Joint Matchers             Non-contact sensorG. Bridenbaugh photo                                  Contact sensor...
ArmSki best for smoothnessAverages optimum HMA thicknessover entire length of ski.
Proper Overlap:1.0 + 0.5 inches.Exception: Milledor sawed jointshould be 0.5inches
Top Photos Show Voids at Bottom of Lift (no overlap)                                    Bridenbaugh & Colella
Bumping the joint?
Don’t broadcast material across the mat
Lute the Longitudinal Joint  This lute person is  doing a great job
No lute person
Rolling the Supported Edge      Our Recommendation:1st pass off the joint   2nd pass overlapapprox 6-8 inches        onto ...
versus an Alternate Method of1st Pass over the Supported Edge                  Roller Make a roller pass in the vibratory ...
Contractor Prior          PlanningConsideration given to mix selectionPlan joint offsets when multiple liftsOn this day go...
Tack Full Width to Minimize Lateral Movement
Paver on Automatic
Vibratory Screed “ON”
End Gate Tightto the ExistingSurface
First Pass Must be Straight
Uniform head of material                     across entire screed to                     joint…Do Not Overload AugerExtend...
Rolling UnsupportedEdge: Overlap 6-incheson the First Pass
Tack / Paint the                    Vertical Face1. Joint Adhesive2. PG Binder3. Double Tack   with Emulsion
Overlap the cold lane by1-inch +/-(unless milled or cutbackjoint, then 0.5-inch)       Use a Joint Matcher
Do Not Push Overlap Back
Rolling Supported Edge: Stay off the Joint6 to 12 inches on the first pass
Attention to Detail                       Making sure                       everything                       is just right...
Mix Selection and Design Considerations Less permeable mixes  • Smallest NMAS that will do the job  • Consider using a “f...
Offsetlongitudinaljoints betweenlayers by at least6-inches
Innovative Techniques /             Materials• Infrared Joint Heaters  – In cold weather• Evaluate Project and Traffic Con...
GOALI-68 project 5+ years old
I-68 project 5+ years old( same project, same location as previous slide )
Industry Help Needed HMA• Concrete getting more competitive due to  HMA cost increase.• Concrete has worked out many of it...
We Know Unsupported Edge Will     Have Lower Density    Proper Overlap   Sufficient Material                        for Ro...
Long Joint Presentation -- Short Version
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Long Joint Presentation -- Short Version

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Long Joint Presentation -- Short Version

  1. 1. Longitudinal Joints in Asphalt Pavements 37th Annual Utah Asphalt Conference March 27, 2012 Howard Anderson, PE. UDOT Central Materials
  2. 2. Acknowledgements• FHWA and Asphalt Institute Partner to Identity Best Practices for Longitudinal Joints. Training Class, February 23, 2012. Mark Buncher, Ph.D., P.E.• NCAT Report No. 97-4 Longitudinal Joint Construction Techniques for Asphalt Pavements.
  3. 3. Best Practices forSpecifying and Constructing HMA Longitudinal JointsA Cooperative Effort between Asphalt Institute & FHWA
  4. 4. Definitions• Longitudinal Joint – HMA placed adjacent to existing lane, Interface between two existing HMA mats.• Hot Joint – Adjacent lanes paved in echelon.• Cold Joint – first pass cooled to ambient temperature with next HMA pass.
  5. 5. Is It a Problem?
  6. 6. An Agency and Industry ConcernLongevity matters, it impacts:  LCC  Alternate Bid Competitiveness  DOT Program Costs  HMA Industry’s Livelihood  the Travelling Public
  7. 7. Project Team– Asphalt Institute • Mark Buncher • Carlos Rosenberger • AI Regional Engineers– FHWA • Thomas Harman • Michael Arasteh • Stephen Cooper– PA State Asphalt Paving Association • Gary Hoffman National Asphalt Pavement Association • David Newcomb
  8. 8. How many State Agencies havea longitudinal joint specification? A •About third B •About half C •About two-thirds
  9. 9. Takeaways from FHWA Survey to 52 Division Offices• ½ States are not satisfied with overall performance of L-Joints• 2/3rds of States have a “L-Joint spec” – Half of those (17) require a minimum density • Range from 89% - 92% min Gmm (Rice) – Other half are method specs • From Joint Adhesive to very prescriptive
  10. 10. GETTING STARTED OFF RIGHT Plant Paving 3 2 1Trucking Compaction Dump Person MTV
  11. 11. Managing Material in the HopperConveyor area is exposed and augers are starved!
  12. 12. Tack CoatFull width of mat tominimize movement ofunsupported edge
  13. 13. Dump Person
  14. 14. First Pass Must Be Straight!Unanimous that a string-line should be used to assure first pass is straight String-line Skip Paint Reference
  15. 15. Great Results
  16. 16. Paver operator usingthe curb as his reference
  17. 17. Tough to get proper overlap (1”) with next pass
  18. 18. Use Automatic Control SystemsContact Grade Sensor Ultrasonic Grade Sensor
  19. 19. Vibratory Screed Should Always Be On
  20. 20. Achieving Pre-Compaction Screed Weight Forward Motion Vibration Screed Heating Angle of AttackDepartment, Name, 23 DateSecurity Class
  21. 21. END GATESeated on the ExistingSurface
  22. 22. Auger Uniform Head of Material Across the Entire ScreedCarry Material Within 12 – 18-inches of the End Gate
  23. 23. Another example ofuniform head ofmaterial
  24. 24. Hydraulic Extending Tunnels Controlling material flow at outer edges of screed and delivering homogenous HMA Tunnels
  25. 25. Result of uniform head of HMAand auger/tunnel within 12 to18-inches of end gate: non-segregated HMA at the joint
  26. 26. Auger Overload…these areunacceptable
  27. 27. Auger not extended towithin 12 to 18-inchesof the end gate.The result -SEGREGATION at joint
  28. 28. Rollers Need to Be Kept Close to the Paver Critical in cool and cold weather!
  29. 29. Our Recommendation:1st Roller Pass Hangs Over 4-6 inches
  30. 30. Alternative: Stay Back 4-6 incheson 1st pass, then roll 2nd pass w/ slight overhang • Concern: –developing stress crack? • Merit: –minimize lateral movement?
  31. 31. What We Don’t Want Rolling Unsupported Edge (First Paver Pass) Edge of drum inside unsupported edge can cause cracking near the edge
  32. 32. Compacting Notched Wedgeadd-on vibratory compactor plate compactor
  33. 33. Quality Control, Monitor Joint Density
  34. 34. Tack the Joint! (Butt or Wedge) Emulsion, orGood, Better, Best PG asphalt or Proprietary Joint Adhesive (JA)
  35. 35. Paver Automation Using Joint Matcher(versus Ski) to Always Achieve Exact Thickness of Mat NeededIf the joint (hot-side) isstarved of material, the rollerdrum will “bridge” onto thecold mat and no furtherdensity will occur at joint. Toensure this never occurs,target height difference aftercompaction is 0.1”
  36. 36. Destined for Hot side of jointFailure starved of material. Bridging?
  37. 37. Types of Joint Matchers Non-contact sensorG. Bridenbaugh photo Contact sensor Frank Colella photo
  38. 38. ArmSki best for smoothnessAverages optimum HMA thicknessover entire length of ski.
  39. 39. Proper Overlap:1.0 + 0.5 inches.Exception: Milledor sawed jointshould be 0.5inches
  40. 40. Top Photos Show Voids at Bottom of Lift (no overlap) Bridenbaugh & Colella
  41. 41. Bumping the joint?
  42. 42. Don’t broadcast material across the mat
  43. 43. Lute the Longitudinal Joint This lute person is doing a great job
  44. 44. No lute person
  45. 45. Rolling the Supported Edge Our Recommendation:1st pass off the joint 2nd pass overlapapprox 6-8 inches onto the cold mat
  46. 46. versus an Alternate Method of1st Pass over the Supported Edge Roller Make a roller pass in the vibratory mode overhanging 2 to 4-inches on the cold side. Concern is bridging (roller being supported by cold mat)
  47. 47. Contractor Prior PlanningConsideration given to mix selectionPlan joint offsets when multiple liftsOn this day goal was 35 ft/min •Plant tons/hour •# of trucks •Plant to project (time) •Type of project (rural/urban) •Ambient / Surface temps •Paver speed •# of rollers
  48. 48. Tack Full Width to Minimize Lateral Movement
  49. 49. Paver on Automatic
  50. 50. Vibratory Screed “ON”
  51. 51. End Gate Tightto the ExistingSurface
  52. 52. First Pass Must be Straight
  53. 53. Uniform head of material across entire screed to joint…Do Not Overload AugerExtend auger andtunnel within 12 to 18-inches of the end gate
  54. 54. Rolling UnsupportedEdge: Overlap 6-incheson the First Pass
  55. 55. Tack / Paint the Vertical Face1. Joint Adhesive2. PG Binder3. Double Tack with Emulsion
  56. 56. Overlap the cold lane by1-inch +/-(unless milled or cutbackjoint, then 0.5-inch) Use a Joint Matcher
  57. 57. Do Not Push Overlap Back
  58. 58. Rolling Supported Edge: Stay off the Joint6 to 12 inches on the first pass
  59. 59. Attention to Detail Making sure everything is just rightMonitor density withgauge, on both sides ofthe joint, as part of QCprogram
  60. 60. Mix Selection and Design Considerations Less permeable mixes • Smallest NMAS that will do the job • Consider using a “fine” gradation • Lower gyration levels Min lift thickness is NMAS x 4, exception: for “fine” gradation NMAS x 3 Warm Mix Asphalt may serve as compaction aid Pay for tack as a separate bid item to facilitate properapplication rate Consider use of the notch wedge joint (versus butt) forlift thicknesses > 1.5 inches and < 3 inches
  61. 61. Offsetlongitudinaljoints betweenlayers by at least6-inches
  62. 62. Innovative Techniques / Materials• Infrared Joint Heaters – In cold weather• Evaluate Project and Traffic Control Requirements for: – Echelon Paving – Mill / Fill One Lane at a Time – Cutting Back the Joint• Consider Joint Enrichment – Overbanding with PG Binder – Use of Surface Sealers
  63. 63. GOALI-68 project 5+ years old
  64. 64. I-68 project 5+ years old( same project, same location as previous slide )
  65. 65. Industry Help Needed HMA• Concrete getting more competitive due to HMA cost increase.• Concrete has worked out many of its problems with smoothness.• HMA problems with Longitudinal Joints, durability, dry mixes.• UAPA can bring one voice to UDOT to represent best interest of the industry, not just one contractor.
  66. 66. We Know Unsupported Edge Will Have Lower Density Proper Overlap Sufficient Material for Roll-Down Low Density Area

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