High Performance Racetracks Good for a Racetrack, Good for a Highway? 38 th Annual Rocky Mountain Asphalt Conference and Equipment Show Brian D. Prowell, Ph.D., P.E.
Road Courses Advanced Materials Services Daytona International* Portland International Raceway Lime Rock Park Palm Beach International Circuit Gilles Villeneuve Repair Watkins Glen* Phoenix International Chicagoland Summit Point Collective Experience Ovals Miami-Homestead* Richmond International* Martinsville Speedway* Talladega Superspeedway* Darlington Raceway Daytona 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.)
Brian Prowell 12/4/08 Removed NASCAR, added last bullet, edited surface friction sub bullet 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 12/4/08 Good to add a race car picture to this slide 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 12/4/08 Switched pictures upper left Raveling C/o A. Wilson
Transverse Joints Joint
Slippage
Typical Demolition Take down all SAFER TM wall Take down catch fence if banking exceeds 24 degrees Light poles? Remove asphalt and base if reconstructing Mill
What is SAFER TM Wall? Courtesy of Elrod Corporation Developed by University of Nebraska - Lincoln
Demolition
Grade and Compact
Brian Prowell 12/4/08 Do you have a better milling picture from Miller? Milling
Scabs
Assess the milled surface
Weak Spots
Brian Prowell 12/4/08 Modified thrid bullet 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
Poor Drainage?
Brian Prowell 12/4/08 new slide Deterioration Due to Water
Drainage Layer
Brian Prowell 12/4/08 Added separation geotextile 1.5 in. 1.5 in. 2.0 in. Typical Track Section HMA Wearing Course HMA Leveling Course HMA Base Course Drainage Layer (optional) Aggregate Subbase Separation geotextile (?) Subgrade or embankment soil
Brian Prowell 12/4/08 Added 3/8 inch to second major bullet 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!
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 Slat Conveyor
Tamping Bar Screed Paver Can obtain up to 90% G mm 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 10 Feet in curves
Tack
Pave to String Line
Precision Mill Leveling
Come off Shims
Ski with Reference to New Mat
Brian Prowell 12/4/08 Added title Typical Paving Train
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
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
Brian Prowell 12/4/08 Added quote about best designed mix 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.
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 Base And Leveling Monitored with gauge, accepted with cores
QA Density Talladega Nuclear Gauge Avg. Mat = 94.2% G mm Avg. Joint = 92.1% G mm Darlington January 12, 2008 Avg. Density: Cores 93.9% G mm Gauge 93.7% G mm
Put Curbs in After Asphalt Finished Asphalt higher than curb
Attention to Detail
Attention to Detail
Brian Prowell 12/5/08 Fly in picture with foot and oval Attention to Detail Immediately after rolling Different track after one year
Attention to Detail
Testing
What Do You Need to Pave a Racetrack?
Thanks! Brian Prowell Advanced Materials Services, LLC 2515 E. Glenn Ave., Suite 107 Auburn, AL 36830 (334) 246-4428 Brian@AMSLLC.US