SMA South of the BorderSMA South of the Border

Alexander (Sandy) Brown, P.Eng.Technical Director, Ontario Hot Mix Producers Association

Canadian Regional Engineer, Asphalt Institute

www.ohmpa.org We’re Driven www.asphaltinstitute.org

Use of SMA in the United Use of SMA in the United StatesStates

Used routinely as surface by 28 states in Used routinely as surface by 28 states in 2007 and a few more since2007 and a few more since

Used primarily in states where there is a Used primarily in states where there is a ready source of good aggregateready source of good aggregate

SMA requires higher quality aggregate to SMA requires higher quality aggregate to resist polishing and resist crushing from resist polishing and resist crushing from stone on stone contactstone on stone contact Haul distance is critical to the useHaul distance is critical to the use States without adequate local aggregate have States without adequate local aggregate have

tried SMA with limited successtried SMA with limited success Some use of slag aggregates Some use of slag aggregates

Wisconsin Highway Research Wisconsin Highway Research ProgramProgram

Study concluded in early 2007 on HMA surface types Study concluded in early 2007 on HMA surface types to look at SMA vs. dense graded mixes using FHWA to look at SMA vs. dense graded mixes using FHWA RealCost 2.1 (Harold Von Quintas)RealCost 2.1 (Harold Von Quintas) 45 years life with 5% discount rate45 years life with 5% discount rate

Concluded that there was a LCCA advantage for SMA Concluded that there was a LCCA advantage for SMA on low volume asphalt roads (< 300,000 ESALs)on low volume asphalt roads (< 300,000 ESALs)

On moderate to high volume route there was no LCCA On moderate to high volume route there was no LCCA advantage for SMA overlay on JRC pavements, advantage for SMA overlay on JRC pavements, howeverhowever Small sample of relatively young overlays pavementsSmall sample of relatively young overlays pavements Substrate pavement with SMA overlay were rougher and Substrate pavement with SMA overlay were rougher and

more deteriorated than those with dense graded mixes more deteriorated than those with dense graded mixes

NCAT Work with Georgia NCAT Work with Georgia AggregateAggregate

All granite aggregate from GeorgiaAll granite aggregate from Georgia 16% to 44% LA loss16% to 44% LA loss

Trials on the test track using various Trials on the test track using various compactioncompaction 50, 75 and 100 gyrations50, 75 and 100 gyrations 50 blow Marshall50 blow Marshall Regression analysis on GRegression analysis on Gmbmb

35 gyrations 35 gyrations 50 blow Marshall 50 blow Marshall Attributed to high LA loss on course aggregateAttributed to high LA loss on course aggregate Georgia uses 50 gyrations for SMAGeorgia uses 50 gyrations for SMA

Virginia Transportation Research Virginia Transportation Research Council Council

2007 study on the cost of SMA vs. other 2007 study on the cost of SMA vs. other HMA choices for surface courseHMA choices for surface course

Concluded that SMA has a cost advantage Concluded that SMA has a cost advantage in excess of $7,500 per lane-mile in net in excess of $7,500 per lane-mile in net present value costspresent value costs

Saving to Virginia based on exclusive use Saving to Virginia based on exclusive use of SMA estimated to be $25 million net of SMA estimated to be $25 million net present valuepresent value

Testing for DurabilityTesting for Durability

Looking for a procedure to evaluate the Looking for a procedure to evaluate the durability of HMA mixes including SMA and durability of HMA mixes including SMA and porous asphalt mixes by FHWAporous asphalt mixes by FHWA AAsphalt sphalt MMixture ixture PPerformance erformance TTesterester Formerly the Formerly the SSimple imple PPerformance erformance TTester ester

Thank youThank you

Any questionsAny questions