Interlayer Materials

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Interlayer Materials Benefits

• Scott Dmytrow
• PPTG Interlayer Co-Chair

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What are Interlayers?

• Pavement interlayers are materials, or
  combinations of materials, which can be placed
  within a pavement during
• new construction,
• rehabilitation or
• preservation
• in conjunction with an overlay or surface
  treatment

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Why Use Interlayers?

• To provide an extension of pavement overlay or
  surface treatment life and thereby lower overall
  life cycle costs.

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How do interlayers do it?

• Moisture barrier
• Reduces crack reflection
• Offers stress relief
• Increased fatigue life

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Types of Interlayers (Based on Maintenance
Technical Advisory Guide or MTAG)
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Paving Fabric Specifications

• Installation with a PG grade asphalt binder
  PG-70-xx or 64-xx
• Binder application shall be 0.25 0.03
  Gal/sq.yd.
• Milled areas require and increase of .05-.10
  Gal/sq.yd

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Paving Mat

• Installation with a PG grade asphalt binder
  PG-70-xx or 64-xx
• Binder application shall be 0.15-.20 0.03
  Gal/sq.yd.
• Milled areas require and increase of .05-.10
  Gal/sq.yd

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Paving Grids (Non Composite)
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Paving Grid (Non Composite)

• Grids with a scrim backing require a tack
  application
• Self Adhesive may require a tack application
• Requires leveling course if milled surface

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Composite Grid
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Composite Grid(s)
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Composite Grid Specifications

• Installation with a PG grade asphalt binder
  PG-70-xx or 64-xx
• Binder application shall be 0.25 0.03
  Gal/sq.yd.
• Milled areas require and increase of .05-.10
  Gal/sq.yd

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Composite Strip Membrane
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Composite Strip Membranes
Primer Placement-The purpose of a primer is to
improve adhesion of the strip membrane under
"marginal" conditions that tend to reduce
bonding.
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Chip or Cape Seals (ARCS, MB (PG-TR, PG-PM), PMRE)
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ARCS Asphalt Rubber Chip Seal

• Specifications are in Chip Seal Chapter of MTAG

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Modified Binder (PG-TR or PG-PM)

• Specifications also in chip seal chapter

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Scrub Seal using PMRE Emulsion
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Scrub Seal using PMRE Emulsion
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Scrub Seal using PMRE Emulsion
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Cape Seal
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Chip over Paving Fabric (aka Geosynthetic
Reinforced Seals)

• Paving Fabric followed by Chip Seal
• Can be covered with Slurry or Overlay

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So why use interlayers?

• Extend Life of Expensive Overlay
• Lower Overall Life Cycle Cost
• Reduce Maintenance

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For Overlay Program Why use an interlayer?
NO INTERLAYER after 2 years
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• Interlayer after 4 years

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Asphalt Overlay Life Expectancy
Pavement Condition Index Serviceability
performance measured by pavement evaluation
methods
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Texas Study
Comparison of reflective cracks in 1.25 and 2.5
asphalt overlay verses 1.25 with paving
fabric TRB, January 1989
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Longitudinal Transverse
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Moving Wheel Load Testing
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A Cautionary Tale about Interlayer Installation

• Surface Prep
• Install Quality Control
• Without these, you could be in jeopardy.
• Look.

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Q Do we really have to crack seal first?
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Structure Considerations

• Remove and Replace Areas which
• Deflect under load
• Have loose pavement chunks
• Show extensive pumping

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Unsuitable for Installation
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Proper Sweeping No water
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Proper Sweeping No water
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Proper Sweeping No water
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Grinding/Milling Quality Counts
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Quality Longitudinal Joint Construction
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Poor Transverse Joint Construction
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Questions?

• MTAG Chapter 12 To be released shortly
• Asphalt Interlayer Association Contact us at
• www.aia-us.org
• California Chip Seal Association
• www.chipseal.org
• You may also contact me at
• scott.dmytrow_at_telferoil.com