Washington County

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Washington County

• Chip Seal Program Review
• Fall, 2011

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• Meeting Format 11/17/11
• Office (1000 to 1100)
• Problem Description
• Chip Seal Program
• Suspected Problem Causes
• Field Trip (1100 to 230)
• Dorland/Moreland/Solberger Rds.
• Lunch
• Reiling/Chalmers/Wilkesboro Rds.
• Riedweg/Dober Rds.
• Wrap up discussion

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• Problem Description
• Possible premature alligatoring on chip seals
  constructed since 2008 (3 years).
• Apparent premature raveling (loss of top course)
  in these chip seals.
• In limited areas, but these problems appear to be
  more prevalent on relatively new projects.

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Moreland Road
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Moreland Road
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• Chip Seal Program
• Single Shot Bituminous surface treatments over
  paved or chip seal roads (1x BST) about 30
  miles per year (1x BSTs are not a problem).
• Three Shot Bituminous Surface Treatments over
  prepared aggregate base (3x BST) about four miles
  per year. Also called gravel road upgrades or
  GRUs.
• 33 miles (40 roads) have been upgraded, mostly
  with 3x BSTs since 2004.

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• Chip Seal Information
• Oil furnished by Albina Oil.
• Base and Chip Seal Aggregate furnished by Baker
  Rock and Westside Rock (2011 only).
• Construction by Washington County Department of
  Land Use and Transportation, Operations and
  Maintenance Division --- Road Crew.
• No formal thickness design. We look for a
  minimum of 6 base rock. Most projects are
  successful.

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• Chip Seal Components
• First shot 0.5 gal/sy prime coat. HFMS or MC-250
  (prior to 2008). ½-1/4 crushed agg. at 35
  lb/sy.
• Second Shot HFE 901s at 0.55 gal/sy. ½-1/4 at
  28 lb/sy.
• Third Shot HFE 901s at 0.45 gal/sy. 3/8-10 at
  28 lb/sy.

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• Possible Causes
• Change from MC-250 to HFMS
• Base rock too clean.
• Base rock too dirty.
• Too much traffic.
• Too little base thickness.
• Isolated drainage issues.
• Top course of chip seal rock dirty?
• Improper mix design same size agg. in layers 1
  and 2?
• Combinations?
• Other issues?

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Roads completed since 2004. Roads to be visited
on field trip are shaded and bolded.
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• Testing Program
• Duval Engineering
• Lab tests by Carlson Testing
• Eight roads, four tests per road. Two from good
  areas, two from distressed areas. 34 total
  testing locations.
• Sand patch test to check surface texture. Rut
  depth measured.
• --- Continued ---

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• Testing Program
• Photo log.
• 8 core taken, plug retrieved and measured.
• Extraction test to determine ac and rock
  gradation.
• Thickness measured.
• Prime coat penetration observed.
• --- Continued ---

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• Testing Program
• Base rock depth measured. Sample retrieved
  (gradation).
• Visual characterization of sugrade observed.
• Subgrade DCP test.
• Subgrade Atterberg Limits test.

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Field Trip Sites