Hot In-Place Recycling

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Construction Troubleshooting

Varying dry and wet spots in mix

  • Check rejuvenating agent application systems
  • Adjust application rates if caused by mix gradation changes

Appearance of broken or dragged aggregate in the mix

  • Slow down and allow material to heat properly to the required temperature

Excessive broken aggregate is an indication of insufficient pavement temperature prior to scarification/augering/milling

Oversize materials or chunks in the mix

  • Slow down and allow material to heat properly to the required temperature
  • Check heater/scarification unit for worn or broken tines or milling teeth and replace

Mix segregation

  • If by mechanical separation, check process flow and screed transfer augers
  • Ensure pavement is sufficiently heated prior to scarification/milling
  • Slow down to increase mixing time

Drag marks in uncompacted mix

  • Check for cool material and possibly increase heat
  • Slow down and allow material to heat properly to the required temperature
  • Look for crack sealant or other foreign material

Flushing of asphalt at surface

  • Check for improper mixing
  • If excessive rejuvenating agent, reduce content
  • If Inadequate mixing of materials, check for signs of wear/build up

Loose material

  • Check for improper compaction
  • Increase rejuvenating agent content

Insufficient compaction

  • Check roller pattern and roller type
  • Add an additional roller
  • Increase heat

Rain

  • Stop the process
  • Ensure the roadway is dry before restarting

If an unrolled HIR mix is caught in a heavy rainstorm, it can be compacted to support temporary traffic. However, the mat will probably not achieve the proper density. The mat can be reworked and compacted when dry conditions allow. 

Post-Construction Troubleshooting

Permanent Deformation

  • Investigate pavement structure in conjunction with mix design lab. Depending on investigation, remove tack and replace affected areas with asphalt mixture (cold mix, recycled mix, WMA, or HMA) or re-recycle

Raveling, Scuffing or Tearing

  • Raveling, Scuffing or Tearing: Sweep and monitor. Determine if fog sealing or re-fog sealing is necessary to protect. Remove tack and replace deep damaged areas with asphalt mixture (cold mix, recycled mix, WMA, or HMA) prior to surface course