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Got Density?

Got Density?. Asphalt Pavement Assn. of Indiana Winter Conference December 2010. Why measure density?. Surrogate for other properties Strength Durability Permeability Easy and fast. Rutting vs. Air Voids. Ref: WesTrack. Rutting vs. Air Voids. 1/2” Rutting in One Year. Ref: Mn/ROAD.

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Got Density?

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  1. Got Density? Asphalt Pavement Assn. of Indiana Winter Conference December 2010

  2. Why measure density? • Surrogate for other properties • Strength • Durability • Permeability • Easy and fast

  3. Rutting vs. Air Voids Ref: WesTrack

  4. Rutting vs. Air Voids 1/2” Rutting in One Year Ref: Mn/ROAD

  5. Fatigue vs. Air Voids Ref: WesTrack

  6. Permeability

  7. Permeability

  8. Retained Penetration vs Air Voids Ref: NCAT Text Book

  9. Pavement Life vs. Air Voids

  10. Getting Density • Lift Thickness • Temperature • Compaction Support • Equipment

  11. NCHRP Report 531 • Relationships of HMA In-Place Air Voids, Lift Thickness, and Permeability (NCHRP 9- 27) • Recommended minimum lift thicknesses: • 3 X NMAS for fine-graded mixes • 4 X NMAS for coarse-graded mixes • Thin lifts cool faster • less time available for compaction

  12. MultiCool • FREE Software for Computing Compaction Window • Base Temp • Weather Conditions • Lift Thickness • Mix Temp • Latitude • Available at www.hotmix.org

  13. MultiCool

  14. Temperature 80OF Surface & Air Temperature, 5 mph wind

  15. Temperature 50OF Surface & Air Temperature, 5 mph wind

  16. Temperature 30OF Surface, 40OF Air Temperature, 15 mph wind

  17. Compaction Support Weak Support Leads to Poor Compaction! Weak!!!

  18. Compaction Support Strong Support Helps Compaction! Strong!!!

  19. Balancing Production • Balance of plant production, trucking, paver speed and rollers • Slow and steady wins the race • Speeding up to get rid of trucks not recommended. • Hurts ride • Non-uniform compaction

  20. Joint Density • Controlling segregation important • Proper joint construction important • Sealers • Echelon paving • Joint density specification

  21. Longitudinal Butt Joint

  22. 1” minimum 12” Max Agg. Size Notched Wedge Joint

  23. Notched Wedge Joint Attachment

  24. First Pass - Steel Wheel Rollers Inside of edge ~ 6” Second Pass - Steel Wheel Rollers Overhang edge 3-6” Joint Rolling - Unconfined Edge

  25. Longitudinal Joint 3” - 6” off joint 3” - 6” on joint Hot Mat Cold Mat

  26. 1/2 - 3/4 “ overlap Longitudinal Joint

  27. Longitudinal Joint Unrolled Rolled

  28. Minimizing Joint Problems • Minimize Joints • Pave in Tandem! • May Require More Lane Closures • But, It Minimizes Return Trips!

  29. 5 6 Final Quiz Q - What is the maximum number of rollers needed on a paving project? A - Whatever it takes to get density. 1 3 4 2

  30. The Future is Bright! • Better Tools to Help Us! • Oscillatory Compaction • Intelligent Compaction • GPS Location • Mat Stiffness

  31. Don’t Forget Quality • Diamond Achievement Commendation • Diamond Quality Commendation • Diamond Paving Commendation

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