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Washington County Road 4: Overlay with Geotextile Fabric

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A presentation given during the 39th Annual NCPA Concrete Paving Workshop. By Shane Swope, P.E., Project Manager, Schemmer & Associates

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Washington County Road 4: Overlay with Geotextile Fabric

  1. 1. WASHINGTON COUNTY ROAD 4 – OVERLAY WITH GEOTEXTILE FABRIC Shane Swope, PE Project Manager, Schemmer
  2. 2. Project Location Blair Herman Hwy77 7mi. Project Area County Road 4, Herman-Scribner Road
  3. 3. Traffic – Minimum Standards  Traffic Volumes – 2014 Counts  388 vehicles per day with 15% to 20% trucks  Minimum Design Standard  Major Collector  11-ft lanes  2-ft shoulders (3-R Min.)  No as-builts exist  Project built in 1993ish
  4. 4. Typical Section  Existing Typical Section  11-ft lanes, 6-ft Shoulders  Many areas with 2:1 foreslopes
  5. 5. Proposed Typical Section  Proposed Typical Section  New & Reconstructed  Require significant ROW and/or miles of guardrail  3-R  11-ft lanes, 6” grade raise, 2-ft Shoulders  2:1 areas regraded with 3:1 to 12-ft fixed obstacle
  6. 6. Roadway Design  Roadway Design  Existing Roadway was Surveyed  Microstation/Geopak Modeling – NDOR process utilized  As-built alignment was created to < 6” difference from survey  Design profile developed  6” overlay and overlay adjustment tools utilized (5% added to quant)  Adjust cross slope back to 2% proposed  Correct areas of minor settlement noted in foundation report
  7. 7. Roadway Design  Roadway Design  Environmental  Wetland delineation completed, but wanted 100% avoidance.  Proposed Phasing  Project closed to traffic in 3 segments.  Access maintained at all times.  Contractor has option of full width paving, half-half, etc.
  8. 8. Existing Pavement Condition  Existing Pavement Investigation  Schemmer Contacted in 2014  Terracon Completed geotechnical in 2013 for Wash. Co  Pavement constructed approx. 1993  Report indicated 6” +/- PCC on 9” Gran Found. Course  Foundation generally good  Pavement materials failing - ASR  Overall smoothness still good where pavement is existing  Very little faulting
  9. 9. Existing Pavement Condition  Existing Pavement Condition, Continued  Longitudinal Cracking  Durability Cracking – Significant  Ongoing joint failures and patching  Handful of full panel failures every year.  No as-builts
  10. 10. Existing Pavement Pictures
  11. 11. Existing Pavement Pictures
  12. 12. Pavement Determination  Pavement Design Background  Consulted with Bill Cook, NCPA  Federal Highway Resource Center  Iowa State Univ. – Institute for Transportation – Concrete Overlay  Kansas DOT & Oklahoma DOT “White Papers” for best practices on un-bonded concrete overlays  Propex Geotextile Products  Frank Pace – Field Rep
  13. 13. Pavement Determination  Pavement Design  Evaluated various overlay strategies  Traditional asphalt overlay – 4” to 6”  5 to10 years initial life, Ongoing maintenance mill-fill, remaining life?  Guarantee ongoing maint. within a few years  Higher long term cost due to pavement condition
  14. 14. Pavement Determination  Pavement Design  Concrete overlay  Utilized AASHTO method, various strategies to evaluate existing pavement.  N&R 8” Concrete on prepared grade  3-R 5” overlay with asphalt bond breaker  6” overlay with fabric.  FHWA Resource Center  Utilized Iowa DOT pavement design process to support design
  15. 15. Project Summary - Cost  Alternatives Costs vs. Construction Costs Comparison of Alternatives (todays dollars) Alternative Initial Estimate 5 year 10 year 20+ year Total 20 year invest in today’s $’s Reconstruct 8” Concrete $6,800,000 - $70,000 ($500/mi) $210,000 $7,080,000 4” Asphalt Overlay $2,170,000 $1,085,000 $7,800,000 $100,000 $11,155,000 6” Concrete Overlay $4,000,000 $35,000 ($500/mi) $70,000 ($1000/mi) $280,000 ($2000/mi) $4,385,000 Actual bid slightly more than $3M
  16. 16. Pavement Determination  Selected Pavement Design  Unbonded Concrete overlay – 6” with geotextile interlayer fabric  Schemmer had not utilized fabric  Bill Cook and Propex supplied information  Researched other states for results. Iowa, Oklahoma, Kansas, South Dakota, Wisconsin
  17. 17. Interlayer Fabric Benefits  Pavement Design  Bond breaker non woven interlayer fabric  Benefits Observed  Lower Cost and quick to install  Drainage and resists reflective cracking  No need to match existing joints  No grade raise compared to traditional asphalt bond breaker  Reflective properties for heat absorption during paving (white only)  Glued or nailed to existing concrete  Pavement Drainage  Project includes granular subdrains for drainage layer(s)
  18. 18. Project Summary - Construction  Summary  Drawbacks  Minimize time traffic drives on fabric  Fabric is sensitive to ultraviolet light. Can’t be stored on-site for extended period.  Fabric can buckle under traffic and ahead of paving machine
  19. 19. Project Summary - Construction  Quantities  Project quantity for 6” and 8” concrete approx. 100,000 SY  Included 4,500 SY of full depth pavement repair  Actual patches could have been fewer – concrete vs. asphalt
  20. 20. Project Summary - Construction Fabric Buckling during placement –spec allows cutting Fabric Buckling ahead of paver – little too wet Paving Machine caught fabric Trucks turn tight can buckle fabric
  21. 21. Project Summary - Construction
  22. 22. Thank You! Questions? Shane Swope, PE Schemmer Associates sswope@schemmer.com 402-493-4800

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