The Texas Experience With Crumb Rubber

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The Texas Experience With Crumb Rubber Dale A.
Rand, P.E.
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Texas Strategies

• Rubber Crack Seal
• Hot Asphalt Rubber Seal or Underseal
• Crumb Rubber Modified Permeable Friction Course
• Crumb Rubber Modified HMAC

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Texas Experience With Crumb Rubber
Crack Seal Over 4 million pounds of crack sealant
is used, nearly all of it crumb rubber modified.
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Hot Asphalt Rubber Seal or Underseal

• Low volume, structurally sound but severely
  cracked pavements

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Texas Experience with AR Seal Coat
First use was in 1976 in Bryan and El Paso
districts Between 1976 and 1981, 850 miles of
AR seal coat was placed By 1990, 2,000 lane
miles of AR Seal Coat was placed More than 20
districts have placed AR Seal Coat since 1976 in
70 counties
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Seal Coat - US 90, near Big Bend National Park
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US 90, crack disappearing in 10 year old Seal Coat
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Eight year old Seal Coat
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5 Year Old Seal Coat - IH-10 near Van Horn
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Not all AR Seal Coats Turned out good
Grade 4 Seal Coat
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Another bleeding Seal Coat
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Performance of AR Seal Coat
Experience has mostly been satisfactory Good
construction practices are a must! - Clean or
pre-coated aggregate - Chip spreader staying
close to distributor - Adequate curing of AR -
Correct binder shot rate and aggregate rate
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Crumb Rubber Modified (CRM) Permeable Friction
Course (PFC)

• High volume, structurally sound pavements with
  poor wet weather skid performance

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Porous Friction Course

• PFC Improves Safety By
• Draining water away from the mix
• Reducing Hydroplaning
• Reducing splash and spray
• Improving wet pavement friction
• Improving surface reflectivity
• Reducing traffic noise

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PFC in France
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8 year old PFC in East Texas with Crumb Rubber,
in the rain (no reflective cracking)
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8 year old PFC in East Texas without Crumb
Rubber, in the rain
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6 Yr. Old Crumb Rubber PFC Odessa IH-20 First Job
(Limestone)
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Odessa IH-20 After 6 years
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5 Yr. Old CRM PFC Odessa IH-20, Second job
(rhyolite)
Odessa, 5 years old
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Job 3, Odessa IH-20, Less than 1 year old
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Job 3, Odessa IH-20, Less than 1 year old
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Summary of TxDOT Experience with Crumb Rubber
Modified PFC

• Three jobs in Odessa District (IH 20) with
  excellent performance and no maintenance after
  6,5, 1 year respectively.
• One job in Lufkin District with excellent
  performance after 8 years.
• Improved resistance to reflective cracking.

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Crumb Rubber Modified HMAC(over a Hot Rubber
Underseal)

• High volume, structurally sound, but severely
  cracked pavement

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Texas Experience With CRM Hot Mix

• Before CMHB
• Type F Project in Dalhart Good performance
• Type D project in Amarillo Premature Failure
• Type D project in Tyler Premature Failure
• Intersection in Tyler Good performance
• Type C in Lubbock Raveling
• Type D San Antonio IH 10..Premature Failure

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Texas Experience With CRM Hot Mix

• After CMHB
• CMHB-C in Abilene Good performance
• CMHB- C in Wichita Falls Good performance
• CMHB-C in Beaumont Good performance
• CMHB-C in Lufkin Base Failure
• CMHB-C in Lufkin Recently showed raveling and
  failure
• CMHB-C in Houston . Good performance
• CMHB-C in OdessaGood performance
• CMHB-F in Odessa. Good performance

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Beaumont, US 96 Built in 1994 Excellent
performance, only few cracks in entire project
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It is not all Good! Lufkin US 259 Nacagdoches
County, Premature failure Air voids problems and
possible base failure
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CRM HMAC - US 385Crane County

• Approximately 18 miles of US 385 with reflective
  cracking
• Selected areas milled, Type B HMAC place November
  1997
• Hot Rubber Seal applied
• 2 CRM HMAC laid April 1998

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Benefits

• Resistance to reflective cracking due to
  elasticity of Crumb Rubber Modifier
• Resistance to aging (oxidation) of the asphalt
  film on aggregate particles
• Reduction of Maintenance Costs

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Drawbacks

• Increased initial cost
• Contractor Comfort factor
• Handling difficulties

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