1. Mix Design & Rejuvenators
Grant Wollenhaupt & Jennifer Breuer
Mix Design & Rejuvenators
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2. 1 2 Issues with Current Designs Cracking Raveling
How do we fix these issues?

3. 1
Cracking
Fatigue – Block – Reflective - Thermal

4. Cracking Causes Block Cracking - Old and dried out mix
Mix was placed to dry
Fine aggregate with absorption
Fatigue Cracking –
Excessive loading
Weak surface, base, or subgrade
This surface or base
Poor drainage
Any combo from above

5. Cracking Causes Thermal Cracking- Reflective Cracking –
Incorrect binder grade
Severe climatic changes
Reflective Cracking –
Differential movement between asphalt and concrete layers

6. CRACKING Underlying cracking problem? Mix was placed to dry
High absorption on some local aggregates
Weak base mixtures
Poor drainage
Incorrect binder grades
CRACKING

7. 2
Raveling
Causes and Solutions

8. Raveling Causes? Asphalt Binder has hardened excessively
Poor Quality Mixture
Broken Bond between aggregate and asphalt
OXIDATION
Water / Traffic
Raveling

9. ISSUE SUMMARY Dry Mix Poor Base / Subgrade Drainage
Inadequate binder grade
Increased oxidation
Poor construction

10. Environmentally responsible
Recycled Materials
Huge push for recycled pavements in order to preserve the environment as well as reducing waste and aid in producing a cost effective mix to construct your roadways.
Cost Savings
Environmentally responsible

11. BEST PRACTICES WITH RECYCLE
QUESTION: Can recycling can be done responsibly and still provide performance as well as cost effectiveness?
ANSWER: YES with design changes and rejuvenators

12. UNDERSTANDING YOUR INPUTS
The key to effective design is understanding the products you are incorporating
Aggregate
RAP
RAS
Liquid Binder
Additives

13. REJUVENATORS Hot Topic
Rejuvenation – to restore youthful vigor; make young again
Softening Agent – substance added to a textile in finishing to give a softer handle

14. ? Exposure Time Temperature How much time do we have? Oxidation
Asphalts exposure to oxygen begins a molecular process that causes new polar bonding sites. The increase of the polar sites allow molecules to shuffle looking for bonds that bring it to a thermodynamic stable state. “Self-assemblage” makes the bonds tighter resulting in a stiffer and brittle pavement ?
Exposure
Time
Temperature
How much time do we have?

15. Where does oxidation occur?
Asphalt Storage Temperatures
Mixing Temperatures at Plant
Silo Time
UV and Oxygen Exposure

16. OXIDATION EFFECTS Brittle Binder Poor workability POOR PERFORMANCE
Decreased Elasticity
Increased Stiffness/Viscosity
Brittle Binder
Poor workability
POOR PERFORMANCE
Decreased Flexibility

17. REJUVENATOR MARKET Re-Disperse the asphaltenes
Counter the stiffness of RAP/RAS
Help ratio of asphaltenes to resins and aromatics
Improve workability of the mix
Increase low temperature flexibility

18. Results
Virgin Binder PG Grading
Mixture Grading
Hamburg Results
SCB Results
TSRST
Texas Overlay

19. PG64-22 True Grade. 66. 5-24. 9 PG64-22 5% hydrogreen 61. 0-30
PG64-22 True Grade PG % hydrogreen PG % hydrogreen PG % hydrogreen
Base Oil
w/ Hydrogreen

20. T5RC with 30% rap PG78-20 T5RC with 27%RAP/3% RAS PG90-12
Field Data
Add Rejuvenator
T5RC WITH 27%RAP/3% RAS PG75-23 T5RC WITH 25%RAP/5% RAS PG81-22

21. Hamburg Wheel-Tracker
Source: Laboratory Performance of Green Asphalt in Flexible Pavement Systems

22. Hamburg Results
Source: Laboratory Performance of Green Asphalt in Flexible Pavement Systems

23. SCB
Source: Laboratory Performance of Green Asphalt in Flexible Pavement Systems

24. SCB Results
Source: Laboratory Performance of Green Asphalt in Flexible Pavement Systems

25. TSRST
Source: Laboratory Performance of Green Asphalt in Flexible Pavement Systems

26. TRST Results
Source: Laboratory Performance of Green Asphalt in Flexible Pavement Systems

27. Texas Overlay
Source: FHWA/TX-14/

28. $$$$$$$

29. SUMMARY
Recycle is necessary to maintain roads under current budget To uphold quality of the recycled mixes, rejuvenators are a necessity Design changes are necessary to increase effective binder in mix Final product must be fairly evaluated

30. Grant Wollenhaupt gwollen@researchtoroads.com www.researchtoroads.com
Questions
Grant Wollenhaupt