Construction of RCI Reflective Crack Interlayer

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Construction of RCIReflective Crack Interlayer

• Nicola Upright
• February 20, 2009

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• This section of roadway was chosen because of the
  concrete down the center of the roadway - 18
  wide, old Model T roadway

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• 2007 placed 3,831 tons _at_ 127.50/ton
• Project US 34 Kersey East
• Ave. 400 tons/day
• 2008 placed 12,229 tons _at_ 128.00/ton
• Project US 34 Hardin East
• Ave. 1020 tons/day

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• 2007 Haul was about 45 minutes
• 2008 On-site plant

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Mix Design Information

• We used PG 70-28 for the binder
• 2007 target AC was 9.5
• 2008 target AC was 9.0
• This was changed to 9.2

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Mix Design Information

• Gradation of the mixes were similar
• 75 - Concrete Sand
• 14 - Crusher Fines or 3/8 rock
• 10 - 3/8 rock or fines
• 1 - Lime

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Mix Design Information

• Voids Target was 4.5 5.0
• VMA was 23.1 to 23.5
• Angularity was 45.0 min
• This was lowered on the 2008 project to 43.0 min

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Densities

• 2007 Target was 96.0
• Changed to 95.0
• 2008 Target was 95.0
• Changed to 94.5

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Densities

• Density has to be achieved before the mix
  temperature drops below 275 degrees
• No finish roller is required
• Rollers need to be as close to the paver as
  possible

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Densities

• Density is hard to measure with RCI
• Reasons
• Thin lift
• Very flexible material
• Have used thin lift gauge, regular gauge and cores

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Densities

• For future projects, we are evaluating the
  densities that were achieved on these two
  projects what other states are doing

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Construction

• 2007
• Off-site plant, haul was 45 minutes
• Used a Shuttle buggy, and end dumps
• 2008
• On-site plant, haul 5 to 20 minutes
• Used Windrow Pick-up Machine and belly dumps

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Construction

• Weather Limitations
• 2007 work was done in early June
• Temps 50 to 70 degrees
• 2008 work was done in late July/August
• Temps 80 to 105 degrees
• Warmer weather is better
• Gives you more time to achieve density

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Construction

• End of the day clean up is a challenge

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Construction

• There can be NO moisture on the paving surface
  when paving creates blisters in the mat
• The paver can not be stopped for more than 15
  minutes at any one time

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Construction

• Dont walk in it
• It is sticky
• Hard to do hand work with

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Construction

• RCI is to be covered with the next lift within 5
  days of placement.
• 2007 one stretch was open close to a month no
  problems
• 2008 most was covered within 5 days one area
  was up to two weeks no problems
• Did not appear to be slick in the rain

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Construction

• RCI was topped with PG 64-28
• 2007 3.5
• 2008 2.5 to 3.5

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Performance

• RCI seems to be performing as it is designed to
  do.
• US 85 No cracks coming through where the RCI
  has been placed and cracks are stopping at the
  edge of the RCI

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Future

• Region 4 is looking at another project near the
  Morgan County line on SH 6. The section of road
  has similar structure as US 34.

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Questions???