Mechanistic and Volumetric Properties of Asphalt Mixtures with RAP

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Mechanistic and Volumetric Properties of Asphalt
Mixtures with RAP

• Jo Sias Daniel
• Aaron Lachance

Transportation Research Board Annual
Meeting January 12, 2005
RMRC
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Purpose of Research

• Determine effect on asphalt concrete from
  substitution of RAP for virgin aggregate and
  binder
• Achieve through evaluation of changes in
  volumetric and mechanistic properties of mixtures
  as RAP percentages are increased

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Using RAP in New Mixtures

• Replacement for some of virgin aggregate and
  binder
• Gradation and ac in RAP must be considered
• Black rock condition when RAP is used at low
  percentages
• Blending of ac is more influential to properties
  at higher RAP percentages

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Test Specimens

• Mixes tested at following conditions
• 0 RAP (Control)
• 15 RAP
• 25 RAP
• 40 RAP
• Two RAP sources
• Processed RAP 3.6 ac
• Grindings 4.9 ac

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Mix Design

• Existing NHDOT 19 mm 15 RAP mix design
• Target same gradation while keeping relative
  proportions of virgin blast rock and natural sand
  the same
• Designs follow Superpave procedure

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Processed RAP Gradations
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Grindings RAP Gradations
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RAP Binder Properties

• Processed RAP PG 94-14
• RAP Grindings PG 82-22
• High temp. grades much higher than PG 58-28
  virgin binder
• Based on research by Daniel Kim, expect RAP
  mixtures to be stiffer

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Laboratory Aged Mixtures
(From Daniel and Kim, TRB 1998)
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Processed RAP Mixtures
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Mixture Volumetrics
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Specimen Fabrication

• Mixing
• Compaction
• 4 air voids

COMPACTION MOLD
SUPERPAVE GYRATORY COMPACTOR
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Specimen Fabrication

• Coring
• Cutting

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Test Setup Overview
SPECIMEN
LAPTOP
ENVIRONMENTAL CHAMBER
INSTRON LOAD FRAME
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Test Specimen (Compression)
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Test Specimen (Tension)
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Material Property Tests

• Complex Modulus
• Tension
• Compression
• Creep Compliance in Compression
• Static Creep in Compression (flow time)
• Why These Tests?
• Mechanistic-Empirical Design Guide
• Simple Performance Test

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15 Processed RAP
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Dynamic Modulus (Compression)
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Dynamic Modulus (Compression)
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Dynamic Modulus (Tension)
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Creep Compliance (Compression)
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Static Creep (Flow Time)
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Differences

• Higher asphalt content for 25 RAP
• Finer gradation for 25 and 40 RAP
• Angularity of RAP aggregate
• Higher VMA and VFA for 25 and 40 RAP

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Fine Aggregate Angularity
Comparison Between Aggregates
All void testing was performed in accordance
with ASTM 1252-98, Method A (Standard Graded
Sample Method)
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Fine Aggregate Angularity
Total Values for Each Blended Mixture
All void testing was performed in accordance
with ASTM 1252-98, Method A (Standard Graded
Sample Method)
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RAP Heating vs. Volumetrics
Examine 40 Processed RAP Mixture using same
compaction effort
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Mixture Volumetrics
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Future Work

• Complex modulus testing on grindings mixtures
• Testing of other RAP sources
• Simulate plant mixtures RMRC project

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Acknowledgements

• Recycled Materials Resource Center
• University of New Hampshire
• NH Department of Transportation
• Kim Zienkiewicz, Rebekah Briggs, Felix Rivera,
  Nick Pulire, Nick Flagg

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Questions?