AFK10 April 21, 2005

Structural Study at the NCAT Test Track R. Buzz Powell Dr. David Timm

STRUCTURAL EXPERIMENT 5” 9”7”

Observations 5 inch layers failed about as predicted5 inch layers failed about as predicted Some cracking in 7 inch layersSome cracking in 7 inch layers Modified sections failed first but not by muchModified sections failed first but not by much Less rutting in modified sectionsLess rutting in modified sections

Based on Test Track Work the Following has been Adopted AL, FL, and NC use more fine-graded mixesAL, FL, and NC use more fine-graded mixes FL uses more modified bindersFL uses more modified binders AL, OK, and TN have begun to use SMAAL, OK, and TN have begun to use SMA OK has more confidence in APAOK has more confidence in APA AL, GA and TN have increased AC contentsAL, GA and TN have increased AC contents

Automated QC Testing Utilization of Automation and Real-Time Testing to Improve QC/QA Procedures For Hot Mix Asphalt Dr. Randy West

QC/QA State of Practice Most HMA requirements for QC are quite complex.Most HMA requirements for QC are quite complex. QC focus has shifted to the end product and away from controlling the process.QC focus has shifted to the end product and away from controlling the process. Due to the time lag between production and results, hundreds of tons are likely to have been produced, creating a high risk if mix is out of tolerance.Due to the time lag between production and results, hundreds of tons are likely to have been produced, creating a high risk if mix is out of tolerance.

Automated Asphalt Content Using a Plant’s Controls Use binder flow rate (gal./min. → tons/hr) with a flow meter or non-powered, positive- displacement pump. And feed rates of aggregates and RAP (tons/hr) with belt scales, tachometers and a computer integrator.

AC Content Comparisons Permeable HMA Base Plant Reading 2.1% AC HMA Binder Mix Plant Reading 3.9% AC

Comparison of Binder Viscosity Measurements PG 67-22

Why Warm Asphalt? Research by Stroup-Gardiner and Lange at AU Indicates increased emissions with increased temp.

We Can Reduce Temperatures Today with No Additives Pre-Superpave – typical compaction temperature 275  FPre-Superpave – typical compaction temperature 275  F Place Thicker Lifts – NCHRP 9-27Place Thicker Lifts – NCHRP 9-27 –3 x NMAS for fine graded –4 x NMAS for coarse graded Tarp TrucksTarp Trucks Drier Aggregate – pave under stockpilesDrier Aggregate – pave under stockpiles

What are Warm Asphalt Mixes? Several process have been developed to improve mixture workability allowing lower production and laydown temperatures –WAM Foam – Shell/Kolo Veidekke –Zeolite – Eurovia/Hubbard Construction –Sasobit – Sasol Int./Moore and Munger –New processes

AIRFIELD ASPHALT PAVEMENT TEST PROGRAM (AAPTP)

PROCESS FAA Funded in July 2004FAA Funded in July 2004 Contractor is Auburn UniversityContractor is Auburn University AAPTP Director reports to the College of Engineering not to the Director of NCATAAPTP Director reports to the College of Engineering not to the Director of NCAT Program size $1.6 million per yearProgram size $1.6 million per year WEB Site: Site:

Process Continued Program Coordinating GroupProgram Coordinating Group –14 Members – –Met in October 2004 –Provides overall direction to program –Identifies the projects Project Development PanelProject Development Panel –Project Director –Representative of FAA –Representative of DOD –Two subject area experts

Initial Projects Adjusting PG Binder Grade Selection ProceduresAdjusting PG Binder Grade Selection Procedures Development of Guidelines for RubblizationDevelopment of Guidelines for Rubblization Guidance on the Use of Superpave Mix Design Procedures for Airfield PavementsGuidance on the Use of Superpave Mix Design Procedures for Airfield Pavements Evaluation of SMA for AirfieldsEvaluation of SMA for Airfields

Initial Projects (Cont.) Longitudinal Joint ConstructionLongitudinal Joint Construction Improved OGFCImproved OGFC Evaluate Need and Develop Plan for National Certification of Airport HMA TechniciansEvaluate Need and Develop Plan for National Certification of Airport HMA Technicians

Endurance Limit of Hot Mix Asphalt Mixtures to Prevent Fatigue Cracking in Flexible Pavements Ray Brown Brian Prowell NCHRP 9-38

Flexible (Asphalt) Pavement Fatigue Surface Base Base Base Sub-baseSub-base Subgrade 12” ? Bottom Up Fatigue Surface Top Down Fatigue Surface Long Life Pavement

Tire/Pavement Noise

Pavements tested LocationsLocations –NCAT test track, Michigan, Alabama, New Jersey, Maryland, Colorado, Nevada, California, Arizona, Texas, Florida, Virginia, Minnesota and Colorado Numbers of surfaces testedNumbers of surfaces tested –Total – 244 surfaces –HMA – 201 surfaces –PCCP – 43 surfaces

Average Results Hot Mix AsphaltHot Mix Asphalt –Dense Graded HMA – 97 dB(A) –Stone Matrix Asphalt – 97 dB(A) –New Generation Open Graded Friction Courses Fine Graded – 92 dB(A)Fine Graded – 92 dB(A) Coarse Graded – 95 dB(A)Coarse Graded – 95 dB(A) Portland Cement Concrete PavementPortland Cement Concrete Pavement –Transverse Tined –104 dB(A) –Diamond ground – 99 dB(A) –Longitudinally Tined – 100 dB(A)

QUIET PAVEMENT - Europe Two Layer Porous Asphalt  2.5 cm fine grade (top) 2/6 or 4/8 mm aggregate  4/5 cm course grade 11/16 mm aggregate (lower layer)  8-9 dBA quieter than conventional mixes  4 dBA quieter than single layer (high speed)  Higher cost than single layer mix (25-35 %) 25 mm fine grade 45 mm coarse grade

Bomag’s Asphalt Manager – A First Look Brian D. Prowell

U. S. Demonstration Intelligent compaction forum, sponsored by FHWA, in Auburn, AL December 2004Intelligent compaction forum, sponsored by FHWA, in Auburn, AL December 2004 Testing conducted on BOMAG Asphalt Manager in conjunction with NCHRP 10-65Testing conducted on BOMAG Asphalt Manager in conjunction with NCHRP –Nuclear gage and PQI readings taken after each roller pass –Roller placed in finish position to evaluate use as “testing device”

Example Growth Curve

Evaluation of N Design for Superpave Mixes

Objectives Evaluate performance of Superpave mixesEvaluate performance of Superpave mixes Compare to performance of Marshall mixesCompare to performance of Marshall mixes Find same materials/traffic conditions Find same materials/traffic conditions – PG Binders and same aggregates –Similar traffic/ESAL loading Optimize the Superpave N Design levelsOptimize the Superpave N Design levels

Project Comparisons AgeAge –Marshall years –Superpave years AADTAADT –Marshall - 13,220 –Superpave - 13,971

Thanks