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Asphalt Rubber Research and Development

George B. Way, P.E.Chairman RPA TAB

Retired from ADOT after 35 Years

Ixtapa, MexicoApril 3rd, 2008

Charles McDonaldInventor of

Asphalt Rubber

McDonaldApplying

AR Band AidPatch

Circa 1966

Asphalt Rubber

Band Aid Patch

Circa 1966

Early Development

Phoenix, Arizona failed streets in the 1960’s.McDonalds goal to maintain failed streets until reconstruction.

Early Asphalt RubberSlurry Seal Application

Circa 1970

Early Asphalt RubberChip Seal Circa 1970

Early Chip SealSpray ApplicationOf Asphalt Rubber

Circa 1975

Early Chip SealConveying

Crumb RubberInto Distributor Truck

Circa 1975

By Early 1980’s Numerous Research Reports On Asphalt Rubber Seal Coats, SAM’s & SAMI’s

Documenting Reducing Reflective Cracking

By 1985 AR Mix Design Research & Development, Gap Graded

& Open Graded

• Reduce Reflective Cracking• More Durable Surface• Reduce Raveling • Good Rut Resistance• Good Skid Resistance• Good performance in Hot & Cold Climates

Cracking

Raveling

19901990’’s Development of AR Standards s Development of AR Standards Arizona and ASTMArizona and ASTM

80 percent Asphalt20 percent Ground Tire Rubber

Rubber & Asphalt Mixed together hot to form a binder

Binder pumped into plant and mixed with hot aggregate, hot mix paved as normal

Complies with ASTM 6114 Asphalt-Rubber Spec.

AR Open Graded (ARFC) and Gap Graded (ARAC)Develop Standard Gradations

HMA Dense GradedSurface

Asphalt Rubber Gap Graded Mix

Asphalt RubberOpen Graded Mix

SHRP ResearchI-40 After

Asphalt RubberOverlay of Concrete

Smoothness IRI mm/km Inches/Mile

78

52

26

0

Texas Research on Reduce Splash & Texas Research on Reduce Splash & SpraySpray

Open Graded Concrete

Asphalt Rubber Friction CourseARFC

California & Arizona Research on NoiseAR Open Graded Quietest Surface

Asphalt Rubber Binder Costs & Usage

Year Number of Projects

Total Tons of AR

Average Low Bid $/Ton

1985 3 900 5061990 6 5600 4091992* 9 9700 3511995 41 29000 2552000 54 36000 2752005 47 32000 297

* 1992 Patents on asphalt rubber expire

AR Cost per square meter per one inch (25 mm) thickness

Year HMA AR GapGraded

Open Graded

AR Open Graded

1996 1.60 2.93 1.85 2.72

2000 1.65 2.76 1.86 2.30

2005 1.69 3.05 1.96 2.55

HMA Dense Graded Average Overlay Thickness

140 mm – 5.5 Inches

Asphalt RubberHot Mixes

Average OverlayThickness

45 mm – 1.7 Inches

HMA % of MilesWith Fatigue Cracking

20 %

Asphalt Rubber % Of MilesWith Fatigue Cracking

2 %

Arizona Use of AR Mixes

Arizona DOT Pavements SurfacedWith Asphalt Rubber since 1988

Asphalt RubberPaved Surfaces

1988-200519500 Lane Kilometers

About45 %

Of ADOTSystem Paved

WithAsphaltRubber

Over20

Million Tires

Recycled Since1988

Arizona Asphalt Rubber BenefitsArizona Asphalt Rubber Benefits

Less Reflective CrackingLess Maintenance/More DurableLess RavelingGood Rut ResistanceGood Skid ResistanceSmooth Ride, Less NoiseGood in hot & cold climatesLess Splash & Spray Better DrainageCost Effective, Energy EfficientGood Engineering Use for Old TiresASTM Standard Type Asphalt

Then

NOW

Lawrence of China?Gobi Desert George?

Thank You