1. Research Implementation WHRP Flexible Group
Barry Paye, PE
Chief Materials Engineer
2016 Mid-Continent Symposium

2. Factors Affecting Asphalt Mixture Durability (WHRP 14-06)
General Category
Specific Factors
Environment
Temperature
Moisture
Drainage
Surface
Subsurface
Construction
Weather Conditions
Segregation
Compaction
Joints
Layer Bond
Mixture Composition
Aggregate Properties
Binder Properties
Gradation
Volumetric Properties

3. Volumetric Properties
In-Place Air Voids
Permeability
Strength and resistance to rutting
Stiffness
Resistance to cracking
Effective Volume of Binder
VBE = VMA-Air voids
Durability and resistance to cracking improves with increasing VBE

4. Other Durability Changes
VMA
Increased to 14.5 for 12.5mm LT, MT Mixes in 2015

5. Design VBE NMAS, mm Minimum Design VMA, vol % Design Air Voids,
Minimum Design VBE,
37.5 11 4 7
25.0 12 8
19.0 13 9
12.5 14 10
9.5 15
4.75 16
All SMA 17

6. Cracking Resistance: Effect of VBE

7. Other Durability Changes
VMA
Increased to 14.5 for 12.5mm LT, MT Mixes in 2015
Moisture Sensitivity
Moving the TSR from 70/75 to 75/80 in 2017
Cold Weather Paving
WMA Additive Required below 40F in 2016

8. Air Void Regression Design Mix to standard 4.0% Air Void
Adding AC to get to a 3.0% Air Void
0.2 to 0.3% increase in AC content in a mix
Increase in density targets to 93% in the field
Should yield greater than 10% increase in pavement life
Note: Percent Within Limits Specifications also add to these enhancements (Pilot Stage)

9. Increasing VMA 0.5 Percent Southern Asphalt Zone
Effective Recycled Binder Ratio
Estimated STOA Flexibility Index
12.5 mm
VBE 11.0
PG S
VBE 11.5
9.5 mm
VBE 12.0
VBE12.5
8.0
8.7
9.4
10.1
0.1
7.0
7.7
8.4
9.0
0.2
6.0
6.7
7.3
0.3
5.0
5.6
6.3
0.4
3.9
4.6
5.3

10. Improving Durability Increase Effective Binder Content
Increase design VMA
Decrease design air voids
Decrease design gyrations
Smaller NMAS mixtures
SMA
Polymer modified binder
High effective binder content
Maryland’s high durability mixture

11. Cracking Resistance: Effect of Recycle Content

12. Performance Testing Move to Performance instead of recipe specs
Hamburg Wheel – Moisture & Rutting
I-FIT – Fatigue Cracking
DCT – Low Temperature Cracking
Several WHRP Research Projects Looking at Specification Development of these
Also doing research to validate Asphalt Content via Ignition oven

13. Laboratory Equipment Hamburg Wheel Ignition Oven
Equipment we have or are in the process of acquiring to improve our mixture testing.
Ignition Oven
DCT (photo courtesy of STATE Testing)

14. WHRP Research Asphalt Binder Extraction – NCAT 16-02
Performance Testing – UW-Madison 15-04
Joints and Density – Behnke Materials 15-09
Moisture Sensitivity – UW-Madison (starting)
Balanced Mix Design – NCAT (starting)

15. Binder Spec Changes Prior to 2016
New construction, reconstruction or pavement replacement
PG 58-28
Overlays PG 64-22

16. Wisconsin Climate Zones

17. Binder Grades Southern Zone Northern Zone
New construction, reconstruction or pavement replacement
Upper Layers: PG 58-34
Lower Layers: PG 58-28
Other projects (Overlay, etc.)
All Layers: PG 58-28
Southern Zone

18. Cracking Resistance: Effect of Virgin Binder Low Grade

19. PG 58-28S Versus PG 64-22S Effective Recycled Binder Ratio
Estimated STOA Flexibility Index
12.5 mm
PG S
PG S
19 mm
19 mm
8.0
5.7
6.6
4.3
0.1
7.0
4.6
5.6
3.3
0.2
6.0
3.6
2.3
0.3
5.0
2.6
1.2
0.4
3.9
1.6

20. Cracking Resistance: Effect of Modification

21. 2015 Updates - Tack Coat
Increased application rate from to gal/sy
Unify layers – increased bond strength
“Tack is cheap insurance – Use it!”

22. Tack Application Rates

23. Factors Affecting Asphalt Mixture Durability
General Category
Specific Factors
Environment
Temperature
Moisture
Drainage
Surface
Subsurface
Construction
Weather Conditions
Segregation
Compaction
Joints
Layer Bond
Mixture Composition
Aggregate Properties
Binder Properties
Gradation
Volumetric Properties

24. Questions/Contact
Barry Paye Materials Management Section Phone: