1. 6th China Asphalt Summit
Engineered Ground Tire Rubber (GTR) Modified Binders and GTR Binder Performance Specifications
Presented by:
Gaylon L. Baumgardner
Ergon, Inc.
6th China Asphalt Summit
Shanghai, China
26-28 October 2011

2. 6th China Asphalt Summit GLB 10-18-11
Introduction and Background
Production of Quality GTR Modified Asphalt Binders
Important Parameters
Source Evaluation/Asphalt Binder Selection
Asphalt Binder Compositional Analysis
Ground Tire Rubber Loading
Processing Temperature Optimization
Ground Tire Rubber Particle Size Optimization
Asphalt/Modified Asphalt Specifcations
Summary and Conclusions
6th China Asphalt Summit GLB

3. Introduction and Background

4. 6th China Asphalt Summit GLB 10-18-11
Rubber Reclamation
Today markets exist for approximately 80% of scrap tires generated in areas such as recycling into new tires, tire derived fuel and oil products, civil engineering products, recycling into molded/engineered rubber products, agricultural uses, athletic and recreation applications and rubber modified asphalt among others.
Presently estimates are less that 10% of scrap tires are disposed of in landfills.
6th China Asphalt Summit GLB

5. Rubber Modified Asphalt
Ground Tire Rubber (GTR) is a post consumer polymer fractionally beneficial in modification of asphalt binders.
Benefits of modification of asphalt with GTR are similar to those achieved with virgin synthetic polymers with the exception GTR loadings are typically higher.
Knowledge and technology for processing GTR modified binders are just as critical as with synthetic polymer modified binders e.g. SBS
In the US, Asphalt Rubber or rubber modified bitumen/asphalt is the largest single market for recycled tires and consumes an estimated 12 million tires annually.
6th China Asphalt Summit GLB

6. Rubber Modified Asphalt
In the US Ground Tire Rubber (GTR) is separated into two particle sizes by class “ground” (2000μm and less) and “coarse” (greater that 2000μm)
6th China Asphalt Summit GLB

7. Rubber Modified Asphalt
Rubber produced from ground whole tires contains ~ 30% reactive material for asphalt modification.
Functional yield is dependent of tire composition and asphalt and is directly proportional to rubber particle size and asphalt source.
Terminal blending can be an operations challenge without adequate knowledge of asphalt chemistry, GTR source and processing.
6th China Asphalt Summit GLB

8. Production of Quality GTR Modified Asphalt Binders

9. 6th China Asphalt Summit GLB 10-18-11
Important Parameters
Asphalt Binder Source
Asphalt Binder Composition
GTR Loading/Special Additives
Processing Temperatures
GTR Source/Particle Size
6th China Asphalt Summit GLB

10. Asphalt Binder Selection
Source Evaluation/
Asphalt Binder Selection

11. Binder Compositional Analysis

12. True Grade Range vs. Composition
6th China Asphalt Summit GLB

13. Effect of Ground Tire Rubber Loading

14. Typical GTR Loading for PG76-22 in Respect to Asphalt/Source Chemistry
6th China Asphalt Summit GLB

15. 6th China Asphalt Summit GLB 10-18-11
Effect of GTR Loading on Modified Asphalt Properties
6th China Asphalt Summit GLB

16. Temperature Optimization

17. 6th China Asphalt Summit GLB 10-18-11
Processing Temperature Optimization
– Phase Angle
6th China Asphalt Summit GLB

18. Ground Tire Rubber Particle Size Optimization

19. 6th China Asphalt Summit GLB 10-18-11
GTR Particle Size Optimization – Phase Angle
6th China Asphalt Summit GLB

20. 6th China Asphalt Summit GLB 10-18-11
GTR Particle Size Optimization – Phase Angle
6th China Asphalt Summit GLB

21. Asphalt/Asphalt Specifications

22. Grading of Asphalt Binders
Prior to 1970 asphalts were specified as penetration grades.
5/9, 50/60, 60/70, 85/100,140/160 and >300 pen
Beginning in 1970, asphalts were specified as viscosity grades.
AC-5, AC-10, AC-20, AC-30 and AC-40
6th China Asphalt Summit GLB

23. Grading of Asphalt Binders Continued
In the 1990’s State DOT’s began to specify SHRP or Performance Grades of Asphalts. SuperPave™.
PG 58-28, PG 64-22, PG 70-22, PG 76-22, etc
Though asphalt specifications have been upgraded through time, any of the are previous grading systems are subject to use.
6th China Asphalt Summit GLB

24. Grading of GTR Modified Asphalt Binders
Due to inherent difficulties of testing GTR modified asphalt binders with, penetration, viscosity and performance grading methods, GTR modified binders have been mostly tested with rotational or vane shear viscosity measurements
6th China Asphalt Summit GLB

25. 6th China Asphalt Summit GLB 10-18-11
Modified Bitumen Binder Testing
Source:Baumgardner/Anderson-Trans-Polyoctenamer Reactive Polymer/Recycled Tire Rubber Modified Asphalt: Processing, Compatibility and Binder Properties 5th Internatioinal Transporttion Conference Wuppertal DE 2008
6th China Asphalt Summit GLB

26. 6th China Asphalt Summit GLB 10-18-11
Parallel Plate
6th China Asphalt Summit GLB

27. How to Handle Larger GTR Particle Size?
60 mesh and smaller material is easily handled with 1mm gap
30 to 60 mesh material would require larger, 2mm gap
20 mesh and larger may require larger gaps
What is the limit to gap size?
Are other geometries available to test larger particles?
6th China Asphalt Summit GLB

28. Comparison of Measurments at 1 and 2 mm gaps
6th China Asphalt Summit GLB

29. Parallel Plate DSR Testing
6th China Asphalt Summit GLB

30. 6th China Asphalt Summit GLB 10-18-11
Concerns
Large gap requirements due to larger particles
Trimming of parallel plates
Sedimentation of particulates
Deformation of asphalt at geometry surface, rather than entire volume of GTR sample
6th China Asphalt Summit GLB

31. 6th China Asphalt Summit GLB 10-18-11
Cup & Bob
Top View
6th China Asphalt Summit GLB

32. 6th China Asphalt Summit GLB 10-18-11
Conventional DSRs
Malvern Instruments
Kinexus Pro Rheometer
Active Heated Chamber
Used with 25mm parallel plates
Peltier Cylinder Cartridge
Used with Cup & Bob and Cup & Vane
6th China Asphalt Summit GLB

33. New Geometry Evaluation
Preliminary testing indicates that new geometry may give similar results
Plate/Plate provides similar results to cup and bob
Trimming of samples is not required when using cup and bob geometries
Accurate measurements can be generated if sedimentation of particulates occurs during the tests using cup and bog geometry
6th China Asphalt Summit GLB

34. PG Continuous grading for blends using different Geometries
BBR
PP1
PP2
C&B
PAV DSR
6th China Asphalt Summit GLB

35. MSCR Jnr 0.1kPa Data for various blends
6th China Asphalt Summit GLB

36. MSCR Jnr 3.2kPa Data for various blends
6th China Asphalt Summit GLB

37. New CRM spec to match MSCR Binder Spec
Original
DSR G*/sinδ Min 1.0 64
RTFOT
64 Standard
MSCR3.2 <4.0
64 Heavy
MSCR 3.2<2.0
64 Very heavy
MSCR3.2 <1.0
PAV
S grade
DSR G*sinδ
Max 5000 28 25 22 19 16
H & V grade DSR G*sinδ Max 6000
[(MSCR3.2 – MSCR 0.1)/ MSCR 0.1] < .75
Low temp BBR and DTT remain unchanged

38. 6th China Asphalt Summit GLB 10-18-11
Summary
Rubber produced from ground whole tires contains ~ 30% reactive material for asphalt modification.
There is nothing to GTR modified asphalt production, that makes it any better or worse than other modifiers, 100% – improved performance modified asphalt can be produced with most all modifiers as long as proper engineering and evaluation is performed.
Careful formulation is needed to meet all specifications.
Asphalt source and chemistry directly effect rubber loading and the end properties of GTR modified asphalt.
Processing parameters Time/Temperature/Processing are important factors.
GTR particle size and source greatly effects the efficiency of modification as well as long term performance.
6th China Asphalt Summit GLB

39. 6th China Asphalt Summit GLB 10-18-11
Summary
Testing of GTR binders is difficult with standard and perfomance grade methods.
Geometries are available for testing of GTR modified binders for performance grade specifications, cup and bob.
There may be some differences for GTR modified binders vs. PMA binder specifications.
Continued evaluation is underway to evaluate new geometry and develop performance grade specifications for GTR modified asphalt binders.
6th China Asphalt Summit GLB

40. Thank You!