Research Implementation WHRP Flexible Group

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

2. Factors Affecting Asphalt Mixture Durability (WHRP 14-06)

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

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

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 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 17-04 (starting) Balanced Mix Design – NCAT 16-06 (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 • 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 • All Layers: PG 58-28

18. Cracking Resistance: Effect of Virgin Binder Low Grade

19. PG 58-28S Versus PG 64-22S

20. Cracking Resistance: Effect of Modification

21. 2015 Updates - Tack Coat Increased application rate from 0.025 to 0.05-0.07 gal/sy Unify layers – increased bond strength “Tack is cheap insurance – Use it!”

22. Tack Application Rates

23. Factors Affecting Asphalt Mixture Durability

24. Questions/Contact Barry Paye Materials Management Section Phone: 608-246-7945 Email: Barry.paye@dot.wi.gov