Stone Matrix Asphalt (SMA) for Airfield Pavements
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Stone Matrix Asphalt (SMA) for Airfield Pavements 2010 FAA Worldwide Airport Technology Transfer Conference . Brian Prowell Don Watson Graham Hurley Ray Brown. Acknowledgements.

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Brian Prowell Don Watson Graham Hurley Ray Brown

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Stone Matrix Asphalt (SMA) for Airfield Pavements2010 FAA Worldwide Airport Technology Transfer Conference

Brian Prowell

Don Watson

Graham Hurley

Ray Brown


Acknowledgements

  • This work was conducted as part of the Airfield Asphalt Pavement Technology Program Project 04-04, Evaluation of Stone Matrix Asphalt for Airfield Pavements.


Background

  • SMA designed in Germany in the 1960’s as mix resistant to studded tires

  • Adopted in US in 1991


Gradation


Aggregate SkeletonStone Matrix Asphalt Mix


Aggregate SkeletonDense-Graded Mix


9.5 mm NMAS SMA Surface Texture


How is SMA Different?

  • Gradation

  • Asphalt Content

  • Dust Content

  • Stabilizing Additives


SMA Performance in the USA

  • Marshall- 50 blow design has been used

  • Improved performance over HMA


Objectives of AAPTP 04-04 Study

The objectives:

  • Evaluate performance of SMA pavements

  • develop technical guidance for the FAA to implement SMA on U.S. airfields


Documented SMA Use on Airfields

  • Australia

  • China

  • Europe

    • Belgium

    • Germany

    • Italy

    • Norway

  • United States


Experimental Design


Mix Combinations


Rutting Susceptibility

  • Laboratory evaluations typically show SMA to have increased rutting susceptibility compared to HMA

  • Experiments to compare SMA and P401

  • Three tests: stability and flow, repeated-load creep, and Hamburg wheel-tracking


Stability and Flow


Repeated Load Permanent Deformation to Asses Rutting Potential

  • 100 mm diameter, 150 mm height

  • 6% air voids

  • 58 C (climatic high temp. - 6 C )

  • 20 psi confinement

  • 0.1 second load; 0.9 second rest

  • 100, 200, 350 psi vertical load

  • Continue for 10,000 cycles or until tertiary flow


With the repeated load test the permanent deformation performance of SMA mixtures and P401 mixtures were not significantly different.


Hamburg Test

Test combines rutting performance with moisture susceptibility

  • Uses a steel wheel 47 mm wide by 204 mm diameter

  • Load = 685 N (154 lb)

  • Full test is 20,000 cycles

  • Temperature - 50 C

  • VTM - 6 + 0.5 %

  • Tested under water


With Hamburg, rutting very similar for P-401 and SMA


Overlay Tester Results


Fuel Resistance

  • China has reported that SMA improves fuel resistance

  • AAPTP 05-02 evaluating fuel resistant sealers and binders

  • Citgo Fuel Resistance Test

    • Soaked in kerosene for 24 hours

    • Mass loss less than 5% good


Fuel Resistance


Deicer ResistanceImmersion Tensile Test


Two Case Studies

  • Aviano AFB, Italy

  • Spangdahlem AFB, Germany


Aviano SMA

Constructed in 1999

Provided good performance up through 2010

Some water issues

More rubber build up

No grooving


Rubber Build Up on SMA Aviano Air Force Base 2000


Aviano Surface Texture in 2000


Seepage of Water from Underneath, Aviano 2000


Draindown, Aviano 2000


Aviano, 2006


Aviano 2008


SMA Aviano

  • Provided good performance to date

  • Good friction

  • Some water issues

  • No grooves


Based on good performance at Aviano, SMA was used at Spangdahlem in 2007


Spangdahlem AFB

  • Milled and overlaid with SMA in 2007

  • High density obtained

  • Some water vapor (blisters) problems


Spangdahlem 2006, patch


Spangdahlem 2006, cracking and condition of grooves


After mixture was milled, approximately 2 weeks of rainfall occurred causing the asphalt mixture to become soaked with moisture


Construction in 2007

  • The contractor used two asphalt plants, two pavers, and up to 8 rollers

  • In place air voids were typically 3 to 4 percent


Spangdahlem, 2007, moisture on surface of SMA


Spangdahlem, 2007, blisters caused by water vapor


Plans are underway to remove and replace the SMA at Spangdahlem


Summary of SMA / P401 Comparison

1Based on laboratory tests performed as part of this study.

2Based on review of the literature or in-service performance.


Recommendations

  • SMA could cost 82 to 94 percent more than dense-graded mixes and still be cost effective on a life-cycle basis.

  • SMA is not typically suited to small quantity production

  • 65 gyrations recommended as alternative to 50-blow Marshall


Questions?

The complete report is available at: www.AAPTP.US

Contact Information for authors:

Ray Brown [email protected]

Brian Prowell [email protected]

Don Watson [email protected]

Graham Hurley [email protected]


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