Performance of

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Performance of Stone Matrix Asphalt Pavements
in Maryland
L. Michael G. Burke C. Schwartz AAPT
2003 Lexington, KY
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Marylands First SMA 1992 First Superpave 1995
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Since 1996 Maryland has been designing SMA with
SGC
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Since 1997 Maryland has been using PG Binders...
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GRADATION SPECIFICATION
19.0 mm 100 82-88 -60 20-28 14-20 9-11
12.5 mm 100 90-99 70-85 30-50 20-33 8-11
9.5 mm 100 100 70-90 30-50 20-30 8-13
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The Gap-Graded Specimen shall conform to the
following
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CHARACTERISTICS
Superpave SMA
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DECISION POINTS FOR USING SMA

• 2000 ESALs per day
• 55 mph

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MD SMA LANE MILES
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NUMBER OF PROJECTS BY MIX TYPE
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12.5 mm
19 mm
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12.5 mm
19 mm
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12.5 mm
19 mm
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12.5 mm
19 mm
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RUTTING PERFORMANCE
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ROUGHNESS (IRI)
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FRICTION
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CORRELATIONS

• SMALL RANGE OF PERFORMANCE
• SMALL RANGE OF MIX PROPERTIES

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SUMMARY

• Performance and material property data for 85 SMA
  projects
• 1300 lane miles
• Up to 10 years service life
• Primarily 19 and 12.5 mm SMA mixes
• Excellent performance
• Rutting 0.04 inches/year (avg)
• Roughness (IRI) 3.2 in/mile-year (avg)
• Friction (FN) 1.3/year (avg)

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SUMMARY

• Inconclusive correlations between performance and
  mix properties
• Too little variation/deterioration of performance
• Too little variation in mix properties

Many of the Maryland SMA sections look better
today than when first opened to traffic!
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THE END