1. VDOT’S PREVENTIVE MAINTENANCE TECHNIQUES & EXPECTATIONS
Todd Rorrer
Regional Field Engineer
CO Asphalt Programs
2017 Asphalt Regional Seminars

2. VDOT’S PREVENTIVE MAINTENANCE TECHNIQUES & EXPECTATIONS
Thin Hot Mix Asphalt Concrete Overlay (THMACO)
Surface Treatments/ Seal Coats
Slurry Surfacing and Micro Surfacing
Cape Seal (Surface Treatment and Slurry Combined)
SM-4.75
Introduction, Project Communication, & Safety

3. Thin Hot Mix Asphalt Concrete Overlay

4. THMACO Thin Hot Mix Asphalt Concrete Overlay
Preventative Maintenance Overlay and Bonding Agent for Composite Pavement Rehab
Requires a specialized spray-bar paver or hot applied polymer modified tack
Tack application rate is .25 +/- (0.03) Gal/sq yd
Delivery temperature is 315oF +/- 15oF measured in the paver hopper
Base Temperature 50oF or higher
Accepted based on Visual Inspection
Rejection requires remove and replace
No Price Adjustments
New for 2017 PG Binder has been corrected to PG 64V-28
One year warranty against raveling and delamination
By Special provisions – Not in Standard Specification at this time
Introduction, Project Communication, & Safety

5. THMACO Laydown and Paver
Introduction, Project Communication, & Safety

6. THMACO Laydown and Paver
Introduction, Project Communication, & Safety

7. THMACO Laydown and Paver
The most essential part of project planning and organization is communication.
Effective communication is vital to all elements of project organization
Discuss project documents versus contract documents.
Technicians must know which materials supersede others.
Introduction, Project Communication, & Safety

8. THMACO: Proper mat with proper overspray
Introduction, Project Communication, & Safety

9. Potential Issues THMACO Introduction, Project Communication, & Safety
The most essential part of project planning and organization is communication.
Effective communication is vital to all elements of project organization
Discuss project documents versus contract documents.
Technicians must know which materials supersede others.
Introduction, Project Communication, & Safety

10. Bleed off: High tack application and overspray can bleed with heavy rains following laydown
Introduction, Project Communication, & Safety

11. Delamination: Delamination can occur with stuck nozzles on paver Patching or milling may be appropriate
Introduction, Project Communication, & Safety

12. Raveling and Segregation Delivery Temperature is critical Raveling and segregation will occur
Introduction, Project Communication, & Safety

13. Reflective crack and spall, with 2 weeks of traffic
Pavement cracks or joints ¼ inch or more in width shall be cleaned and filled with a sealant material conforming to the Special Provision For Sealing Cracks in Asphalt Concrete Pavements or Hydraulic Cement Concrete Pavement. Quantities and payment will be according to the Special Provision For Sealing Cracks in Asphalt Concrete Pavements or Hydraulic Cement Concrete Pavement.
Introduction, Project Communication, & Safety

14. VDOT Surface Treatments
Generically known as Chip Seals
The most essential part of project planning and organization is communication.
Effective communication is vital to all elements of project organization
Discuss project documents versus contract documents.
Technicians must know which materials supersede others.
Introduction, Project Communication, & Safety

15. VDOT Surface Treatments
Seal Treatment: One Application of liquid asphalt and one application of cover aggregate Modified Single Seal: Two applications of liquid asphalt one application of cover and one application of blot fine aggregate Modified Double Seal: Three applications of liquid asphalt, two applications of cover and one application of blot fine aggregate
Introduction, Project Communication, & Safety

16. Surface Treatments Appropriate uniformity No streaks
Appropriate amount of cover loss with traffic
Introduction, Project Communication, & Safety

17. Proper Surface Texture After Traffic
Introduction, Project Communication, & Safety

18. Potential Issues Surface Treatment
Introduction, Project Communication, & Safety

19. Emulsion Application Rate
Delamination:
Surface preparation
Emulsion Application Rate
Ensure aggregate compatibility
Introduction, Project Communication, & Safety

20. Streaking
Emulsion application rate Calibrate the Distributor Calibrate the chip spreader Ensure aggregate compatibility
Introduction, Project Communication, & Safety

21. Distributor Calibration
Emulsion application rate Spray bar height Speed Required by specification to be performed in front of the Engineer per project
Introduction, Project Communication, & Safety

22. Distributor Calibration
Once height is established, verify the application rate with plate test Required by specification to be performed in front of the Engineer per project
Introduction, Project Communication, & Safety

23. Surface Treatments Bond breakers
Introduction, Project Communication, & Safety

24. Slurry Seals and Micro Surfacing
Introduction, Project Communication, & Safety

25. Slurry Seals and Micro Surfacing
Introduction, Project Communication, & Safety

26. Slurry Seals and Micro Surfacing
Mixture of emulsified asphalt and fine aggregate
Placed in thin lifts to protect and seal current riding surface
Micro Surfacing is a slurry seal using Latex Modified emulsions and additional lab design requirements
Introduction, Project Communication, & Safety

27. Placed in thin lifts to protect and seal current riding surface

28. Slurry Seals and Micro Surfacing
Delamination: Poor surface preparation Gradation and AC content too tight
Introduction, Project Communication, & Safety

29. Surface Preparation and / or Gradation Control
Introduction, Project Communication, & Safety

30. Cape Seals Combination of a Surface Treatment and Slurry Seal
Surface treatment is placed first
Allowed to cure for at two weeks by specification
Surface cleaned and Slurry applied
Introduction, Project Communication, & Safety

31. Cape Seals
Combination of a Surface Treatment and Slurry Seal Suburban Secondary in Chesterfield County, VA Completed Summer of 2016 Current Condition: February 2017
Introduction, Project Communication, & Safety

32. Cape Seals
Suburban Secondary in Chesterfield County, VA Completed Summer of 2016 Current Condition: February 2017
Introduction, Project Communication, & Safety

33. Cape Seals
Suburban Secondary in Chesterfield County, VA Completed Summer of 2016 Current Condition: February 2017
Introduction, Project Communication, & Safety

34. SM-4.75 Preventative Maintenance Overlay

35. SM-4.75 Finer Superpave Mix placed at .75 to 1.25 inches
Used with A, D and E mixes
Minimum of three breakdown passes
Density based on roller pattern and control strip, however CS cores are not taken
Material temperatures are critical, best practices are to work hot to warm in the field
May be rejected based on visual inspection
Platform is critical
Introduction, Project Communication, & Safety

36. New for 2017 – SP Dated July 22, 2016 Last Paragraph of Section VII:
The minimum laydown temperatures:
for SM-4.75A and SM-4.75D shall not be less than 270°F.
For SM-4.75E, the minimum laydown temperature shall not be less than 290°F. 
VIII. Weather Restrictions 
SM-4.75 mixture shall be placed only when the ambient and surface temperature are 50 degree F or above. The Contractor shall employ a Material Transfer Vehicle (MTV) during the placement of SM-4.75 mixtures for the ambient and/or surface temperature between degree F.

37. Smooth uniform surface that protects the underlying pavement

38. SM-4.75 Platform is critical:
Curb and gutter sections need full width milling
Introduction, Project Communication, & Safety

39. Edge Milling, can lead to issues…
Curb and gutter sections need full width milling
Introduction, Project Communication, & Safety

40. Edge Milling, can lead to issues…
Introduction, Project Communication, & Safety

41. SM-4.75 It is much better to plane the entire platform….
Introduction, Project Communication, & Safety

42. Patch out weak spots
Introduction, Project Communication, & Safety

43. Patch out weak spots
Introduction, Project Communication, & Safety

44. SM-4.75 Watch out for over-runs Get a feel for quantities
Introduction, Project Communication, & Safety

46. Thank You
Introduction, Project Communication, & Safety