high performance racetracks...high performance racetracks brian d. prowell, ph.d., p.e. good for a...

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

ADVANCED MATERIALSSERVICES, LLC

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


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.)


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


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


Raveling

C/o A. Wilson

Brian Prowell 12/4/08Switched pictures upper left


Transverse Joints

Joint


Slippage


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


What is SAFERTM Wall?

Courtesy of Elrod Corporation – Developed by University of Nebraska - Lincoln

Demolition


Grade and Compact


MillingBrian Prowell 12/4/08Do you have a better milling picture from Miller?


Scabs


Assess the milled surface


Weak Spots


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


Poor Drainage?


Deterioration Due to WaterBrian Prowell 12/4/08new slide


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


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)


Test Sections Required


Calibrate Nuclear Gauge


Bad Habits in the Test Section – Bad Habits on the Track


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!


Mix Generally Has to be Hauled Through Tunnel as Paving Progresses


Getting Mix to the Paver – A Challenge on Ovals

SlatConveyor


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


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


Cut/fill every 10Feet in curves


Tack

Pave to String Line

Precision Mill Leveling


Come off Shims


Ski with Reference to New Mat

Typical Paving Train

Brian Prowell 12/4/08Added title



You can’t pave 40 feet wide in a single pass!


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


Paving in Echelon


Cut Back Joint


Rolling 6 in. off the joint –


Bad Joint after a few months

Good Joint after 3 years



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


18 – 24 degrees – Support from below


> 24 degrees, suspend from above


Improper support


Compaction Against Wall


Courtesy of Danny James


Seal Joint with Crash Wall


Like on a highway, you need


Density on BaseAnd LevelingMonitored with gauge, accepted with cores


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


Put Curbs in After AsphaltFinished Asphalt higher thancurb


Attention to Detail


Attention to Detail

Immediately after rolling Different track after one year

Brian Prowell 12/5/08Fly in picture with foot and oval


Attention to Detail


Testing


What Do You Need to Pave a Racetrack?


Thanks!

Brian ProwellAdvanced Materials Services, LLC2515 E. Glenn Ave., Suite 107Auburn, AL 36830(334) [email protected]

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