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Construction of Longitudinal Joints

Construction of Longitudinal Joints . 2014 VDOT/VAA Regional Asphalt Seminars Ken Arthur Quality Control Manager Templeton Paving. Relationship between Density and Pavement Life. Low Density Permeability Segregation Poor adhesion at interface.

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Construction of Longitudinal Joints

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  1. Construction of Longitudinal Joints 2014 VDOT/VAA Regional Asphalt Seminars Ken Arthur Quality Control Manager Templeton Paving

  2. Relationship between Density and Pavement Life • Low Density • Permeability • Segregation • Poor adhesion at interface

  3. “You must plan for the longitudinal joint, it cannot be an afterthought”.. Final Draft Report Best Practices for Constructing and Specifying HMA Longitudinal Joints Buncher and Rosenberger, Asphalt Institute 2012

  4. Longitudinal Joint Density • Layout of the Site • Tack Application • Paver Practices • Proper Depth • Proper Overlap • Handwork • Compaction • Quality Control

  5. Layout – 1st Pull • Mark a consistent, straight line for paver operator • Offset 6” from existing joint New joint offset 6” Existing joint

  6. Tacking the 1st Pull 2’ section along center line is tacked first

  7. Good Paver Practice Paver hopper remains open between dumps Material should not be pushed more than 24” to end gate

  8. Paver Practice – 1st Pull • Vibratory screed ON • End gates set for neat butt joint • Augers within 24” of end gate • Consistent paver speed • Non-contact ski for grade control

  9. Definitions

  10. Compaction – 1st Pull Roll unconfined edges with a 6” overlap We generally roll from centerline to outside edge, sealing off longitudinal joint first

  11. Compaction - 1st Pull Beginning just inside of the unsupported edge can cause cracking late in the roller pattern from lateral mix movement Edge of drum directly on edge of unsupported edge will typically cause lateral movement of mat

  12. Longitudinal Joint Density2nd Pull • Proper tack application • Paving practices • Correct depth and overlap of material • Compaction

  13. Tacking the 2nd Pull • Ensure joint is clean • Tack the vertical face of the joint with 0.20 gal/S.Y. prior to paving • Slight puddling at the base of vertical face is acceptable

  14. Tacking the Vertical Face

  15. Paver Practice - 2nd Pull • Consistent paver speed • Joint matcher for grade control • End gates down and augers within 24”

  16. 2nd Pull – Proper Depth • D2 = D1 + 25% • D2 = Depth of 2nd Pull • D1 = Compacted Depth of 1st Pull DON’T STARVE THE JOINT!

  17. 2nd Pull – Proper Overlap • We overlap the joint ½” – 1” • Do not trust the “toe test” • Handwork?

  18. 2nd Pull – No Handwork Necessary “Bumping the joint..….BAD!”

  19. 2nd Pull - Compaction A visible white line is assurance that you are not “starving” the longitudinal joint.

  20. 2nd Pull - Compaction

  21. 2nd Pull - Compaction 2nd Pass will leave 6” – 36” depending on road width 3rd Pass pinches joint with sufficient material to achieve compaction

  22. Longitudinal Joint Density QC • Utilize the gauge beyond minimum requirements • Prioritize density • Have a plan for corrective action

  23. Common Longitudinal Joint Density Issues • Starving the joint, or “bridging” • Excessive grade changes • Paver speed • Rollers unable to keep up with paving operation • Electronics affected by inconsistent speed • Communication between operators and technicians

  24. Longitudinal Joint Density Summary • Layout for straight lines and offset joints • Quality paving practice with the machine • Tack the clean joint location and vertical face • Proper depth and overlap • Compaction with joint density in mind • Diligent quality control

  25. Questions?

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