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

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

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

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

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

Cracking Resistance: Effect of VBE

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

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)

Increasing VMA 0.5 Percent Southern Asphalt Zone Effective Recycled Binder Ratio Estimated STOA Flexibility Index 12.5 mm VBE 11.0 PG 58-28 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

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

Cracking Resistance: Effect of Recycle Content

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

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)

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)

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

Wisconsin Climate Zones

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

Cracking Resistance: Effect of Virgin Binder Low Grade

PG 58-28S Versus PG 64-22S Effective Recycled Binder Ratio Estimated STOA Flexibility Index 12.5 mm PG 58-28 S PG 64-22 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

Cracking Resistance: Effect of Modification

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!”

Tack Application Rates

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

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