High Performance Racetracks
Brian D. Prowell, Ph.D., P.E.
Good for a Racetrack, Good for a Highway?
38th Annual Rocky Mountain Asphalt Conference and Equipment Show
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Advanced Materials ServicesCollective Experience
• Road Courses– Daytona International*– Portland International
Raceway
– Lime Rock Park
– Palm Beach International
– Circuit Gilles Villeneuve
• Repair– Watkins Glen*
– Phoenix International
– Chicagoland– Summit Point
• OvalsMiami-Homestead*Richmond International*
Martinsville Speedway*
Talladega Superspeedway*
Darlington RacewayDaytona International Speedway
*While working for NCAT
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Design Concerns• Racetracks are about entertainment. What
might be a small problem on a highway would be a disaster if it delayed a race
• Smoothness• Durability
– Resistance to raveling
– Resistance to shoving
– Resistance to cracking
• Uniformity (texture etc.)
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Fan Excitement
• A performance specification for a racetrack would provide for “fan excitement or driver entertainment”
• Side-by-side racing, a function of:– Geometry– Surface friction (including rubber laydown)
• The racing surface should not dictate the outcome of the race
Brian Prowell 12/4/08Removed NASCAR, added last bullet, edited surface friction sub bullet
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Thoughts About Forces on a Racetrack Pavement
• Not concerned about rutting like on a highway, port, or possibly an airport taxiway
• Main concern is raveling• Lateral forces are greater on a road course or
flat oval with less banking, like Indianapolis, than on a steeply banked oval, like Talladega
• Down draft on cars produces suction under cars which can pull out loose chunks of pavement or manholes covers.
Brian Prowell 12/4/08Good to add a race car picture to this slide
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Raveling
C/o A. Wilson
Brian Prowell 12/4/08Switched pictures upper left
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Transverse Joints
Joint
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Slippage
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Typical Demolition• Take down all SAFERTM wall
• Take down catch fence if banking exceeds 24 degrees
• Light poles?• Remove asphalt and base if
reconstructing
• Mill
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What is SAFERTM Wall?
Courtesy of Elrod Corporation – Developed by University of Nebraska - Lincoln
Demolition
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Grade and Compact
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MillingBrian Prowell 12/4/08Do you have a better milling picture from Miller?
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Scabs
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Assess the milled surface
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Weak Spots
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Drainage, Drainage, Drainage• Drainage is important to the long-term
performance of a track or any pavement• Some tracks are built in natural bowls, most
tracks have paving behind the crash wall• Edge drains used to intercept water at the
edge of the pavement, behind walls and at the toe of slopes
• Drainage layer can be used to keep water from percolating through the surface of the
Brian Prowell 12/4/08Modified thrid bullet
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Poor Drainage?
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Deterioration Due to WaterBrian Prowell 12/4/08new slide
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Drainage Layer
HMA Wearing CourseHMA Leveling Course
HMA Base Course
Drainage Layer (optional)
Aggregate Subbase
Subgrade or embankment soil
1.5 in.
1.5 in.
2.0 in.
Typical Track Section
Separation geotextile (?)
Brian Prowell 12/4/08Added separation geotextile
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Typical Surface Mix Design• Stiff Binder
– PG 82-XX – XX depends on climate– 180 °F Softening Point– Elastic Recovery – ensure polymer modification
• 9.5 mm (3/8 inch) NMAS Surface– Polish resistant aggregate– 75-Blow Marshall – Gradation close to maximum density line– Good in-place density!
Brian Prowell 12/4/08Added 3/8 inch to second major bullet
Plant on Site or Close By (Ideally)
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Test Sections Required
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Calibrate Nuclear Gauge
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Bad Habits in the Test Section – Bad Habits on the Track
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Begin Paving• Each lift is a dress rehearsal for the surface• Number of passes depends on geometry
– Want to minimize longitudinal joints
– Road courses can be paved in echelon – might not be best choice
– More passes may be needed to minimize grade change at hinge points on ovals
• Check smoothness after each lift• Grind or precision mill as necessary• Goal is a perfect surface!
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Mix Generally Has to be Hauled Through Tunnel as Paving Progresses
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Getting Mix to the Paver – A Challenge on Ovals
SlatConveyor
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Tamping Bar Screed Paver• Can obtain up to
90% Gmm directly behind screed
• Minimizes roll down – 1/8 inch per inch instead of typical ¼ inch per inch
• Less roll down = smoother pavement
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Smoothness
• Grade Control – 3 dimensions in curves
• String lines sometimes used
• Surface placed with paver on automatic– Uniform thickness– Ski with bridge to new mat– Tamping bar screed – minimizes roll down– Stable mix
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Cut/fill every 10Feet in curves
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Tack
Pave to String Line
Precision Mill Leveling
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Come off Shims
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Ski with Reference to New Mat
Typical Paving Train
Brian Prowell 12/4/08Added title
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You can’t pave 40 feet wide in a single pass!
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Longitudinal Joints• A weak point in a racetrack pavement as
well as a highway pavement
• Options– Paving in echelon - generally not possible
on ovals– Stagger joints between lifts– Cut back joints
• Saw• Cutting wheel
– Joint sealant
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Longitudinal Joints• A weak point in a racetrack pavement as
well as a highway pavement
• Options– Paving in echelon - generally not possible
on ovals– Stagger joints between lifts– Cut back joints
• Saw• Cutting wheel
– Joint sealant
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Paving in Echelon
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Cut Back Joint
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Rolling 6 in. off the joint –
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Bad Joint after a few months
Good Joint after 3 years
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Proper Compaction is a Must!
“The best designed mix in the world, poorly constructed, will not perform as well as a
lower quality mix constructed well.”
Brian Prowell 12/4/08Added quote about best designed mix
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18 – 24 degrees – Support from below
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> 24 degrees, suspend from above
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Improper support
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Compaction Against Wall
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Courtesy of Danny James
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Seal Joint with Crash Wall
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Like on a highway, you need
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Density on BaseAnd LevelingMonitored with gauge, accepted with cores
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QA Density
TalladegaNuclear GaugeAvg. Mat = 94.2% Gmm
Avg. Joint = 92.1% Gmm
Darlington January 12, 2008Avg. Density: Cores 93.9% Gmm
Gauge 93.7% Gmm
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Put Curbs in After AsphaltFinished Asphalt higher thancurb
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Attention to Detail
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Attention to Detail
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Attention to Detail
Immediately after rolling Different track after one year
Brian Prowell 12/5/08Fly in picture with foot and oval
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Attention to Detail
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Testing
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What Do You Need to Pave a Racetrack?
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Thanks!
Brian ProwellAdvanced Materials Services, LLC2515 E. Glenn Ave., Suite 107Auburn, AL 36830(334) [email protected]