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

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

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) 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 45 years life with 5% discount rate Concluded that there was a LCCA advantage for SMA on low volume asphalt roads (< 300,000 ESALs) 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 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 Small sample of relatively young overlays pavements Substrate pavement with SMA overlay were rougher and more deteriorated than those with dense graded mixes Substrate pavement with SMA overlay were rougher and more deteriorated than those with dense graded mixes

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

Virginia Transportation Research Council 2007 study on the cost of SMA vs. other HMA choices for surface course 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 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 Saving to Virginia based on exclusive use of SMA estimated to be $25 million net present value

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

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