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SMA South of the Border

SMA South of the Border. Alexander (Sandy) Brown, P.Eng. Technical Director, Ontario Hot Mix Producers Association Canadian Regional Engineer, Asphalt Institute. We’re Driven www.asphaltinstitute.org. www.ohmpa.org. Use of SMA in the United States.

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SMA South of the Border

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  1. SMA South of the Border Alexander (Sandy) Brown, P.Eng. Technical Director, Ontario Hot Mix Producers Association Canadian Regional Engineer, Asphalt Institute We’re Driven www.asphaltinstitute.org www.ohmpa.org

  2. Use of SMA in the United States • Used routinely as surface by 28 states in 2007 and a few more since • Used primarily in states where there is a ready source of good aggregate • SMA requires higher quality aggregate to resist polishing and resist crushing from stone on stone contact • Haul distance is critical to the use • States without adequate local aggregate have tried SMA with limited success • Some use of slag aggregates

  3. Wisconsin Highway Research Program • Study concluded in early 2007 on HMA surface types to look at SMA vs. dense graded mixes using FHWA RealCost 2.1 (Harold Von Quintas) • 45 years life with 5% discount rate • Concluded that there was a LCCA advantage for SMA on low volume asphalt roads (< 300,000 ESALs) • On moderate to high volume route there was no LCCA advantage for SMA overlay on JRC pavements, however • Small sample of relatively young overlays pavements • Substrate pavement with SMA overlay were rougher and more deteriorated than those with dense graded mixes

  4. NCAT Work with Georgia Aggregate • All granite aggregate from Georgia • 16% to 44% LA loss • Trials on the test track using various compaction • 50, 75 and 100 gyrations • 50 blow Marshall • Regression analysis on Gmb • 35 gyrations  50 blow Marshall • Attributed to high LA loss on course aggregate • Georgia uses 50 gyrations for SMA

  5. Virginia Transportation Research Council • 2007 study on the cost of SMA vs. other HMA choices for surface course • Concluded that SMA has a cost advantage in excess of $7,500 per lane-mile in net present value costs • Saving to Virginia based on exclusive use of SMA estimated to be $25 million net present value

  6. Testing for Durability • Looking for a procedure to evaluate the durability of HMA mixes including SMA and porous asphalt mixes by FHWA • Asphalt Mixture Performance Tester • Formerly the Simple Performance Tester

  7. Thank you Any questions

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