VDOT S PREVENTIVE MAINTENANCE TECHNIQUES & EXPECTATIONS

Transcription

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

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

3 Thin Hot Mix Asphalt Concrete Overlay 3

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 315 o F +/- 15 o F measured in the paver hopper Base Temperature 50 o F 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 4

5 THMACO Laydown and Paver 5

6 THMACO Laydown and Paver 6

7 THMACO Laydown and Paver 7

8 THMACO: Proper mat with proper overspray 8

9 THMACO Potential Issues 9

10 Bleed off: High tack application and overspray can bleed with heavy rains following laydown 10

11 Delamination: Delamination can occur with stuck nozzles on paver Patching or milling may be appropriate 11

12 Raveling and Segregation Delivery Temperature is critical Raveling and segregation will occur 12

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. 13

14 VDOT Surface Treatments Generically known as Chip Seals 14

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 15

16 Surface Treatments Appropriate uniformity No streaks Appropriate amount of cover loss with traffic 16

17 Proper Surface Texture After Traffic 17

18 Surface Treatment Potential Issues 18

19 Delamination: Surface preparation Emulsion Application Rate Ensure aggregate compatibility 19

20 Streaking Emulsion application rate Calibrate the Distributor Calibrate the chip spreader Ensure aggregate compatibility 20

21 Distributor Calibration Emulsion application rate Spray bar height Speed Required by specification to be performed in front of the Engineer per project 21

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 22

23 Surface Treatments Bond breakers 23

24 Slurry Seals and Micro Surfacing 24

25 Slurry Seals and Micro Surfacing 25

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 26

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

28 Slurry Seals and Micro Surfacing Delamination: Poor surface preparation Gradation and AC content too tight 28

29 Surface Preparation and / or Gradation Control 29

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 30

31 Cape Seals Combination of a Surface Treatment and Slurry Seal Suburban Secondary in Chesterfield County, VA Completed Summer of 2016 Current Condition: February

32 Cape Seals Suburban Secondary in Chesterfield County, VA Completed Summer of 2016 Current Condition: February

33 Cape Seals Suburban Secondary in Chesterfield County, VA Completed Summer of 2016 Current Condition: February

34 SM-4.75 Preventative Maintenance Overlay 34

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 35

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. 36

37 Smooth uniform surface that protects the underlying pavement 37

38 SM-4.75 Platform is critical: Curb and gutter sections need full width milling 38

39 Edge Milling, can lead to issues Curb and gutter sections need full width milling 39

40 Edge Milling, can lead to issues 40

41 SM-4.75 It is much better to plane the entire platform. 41

42 Patch out weak spots 42

43 Patch out weak spots 43

44 SM-4.75 Watch out for overruns Get a feel for quantities 44

45 45

46 Thank You