Crack Treatment

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Crack Treatment

• Sponsored by Minnesota LTAP Center
• Presented by Michael Marti, P.E.
• SRF Consulting Group, Inc.
• Dan Wegman, P.E.
• SemMaterials

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Filling vs Sealing

• Sealing involves prepping (creating reservoir,
  cleaning, etc) where filling, at most, includes
  blowing the crack clean.
• Crack filling is most often reserved for more
  worn pavements with wider, more random cracking.
• Crack sealing is normally done on cracks which
  are less than ¾-inch wide, are spaced uniformly
  and have limited edge deterioration.

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Methods of Crack Treatments

• Crack Filling
• Preparation is fairly minimal, generally
  consisting of blowing loose debris from the
  crack with compressed air.
• In some cases, you can uses a hot air lance to
  clean and dry the crack before applying the
  filler material.
• Mn/DOT Specification 3719, Crumb Rubber, is
  recommended.
• The use of AC-3 as a crack filler is discouraged.

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Methods of Crack Treatments

• Clean and Seal (formerly blow and go)
• Make sure that cracks are clean and dry before
  placing sealant
• Perform in late fall or early spring when cracks
  are open
• Take care not to burn pavement with hot air lance
• Follow manufacturers recommendations for
  sealant application

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Methods of Crack Treatments

• Rout and Seal
• Over band should be about 2-1/2 inch (¾ route
  plus ¾ over band.
• Over band thickness should be as thin as
  possible.

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Methods of Crack Treatments

• Full-depth crack repair
• Milling depth varies from 1 ¼ for cracks in good
  condition, to full depth for pavements with
  severe deterioration in the crack vicinity.
• Mill width varies from 10 to 12 for shallow
  milling, to 3 to 4 for deep milling.
• When choosing the configuration of the area to be
  milled, the trench should be wide enough to
  ensure good compaction. It is difficult to
  achieve good compaction in a deep narrow trench.

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Methods of Crack Treatments

• Crack Sealing and Overlays
• Crack sealing is recommended 6 to 12 months prior
  to an overlay.
• To eliminate bumps caused by too much or reactive
  sealant.

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Methods of Crack Treatments

• Saw and Seal
• Place the sealant flush to the pavement surface.
• The strike-off will create a slight over band
  that provides better adhesion of the sealant to
  the pavement surface/reservoir edge corner.

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Recommended Applications
Material Mn/DOT Spec Recommended Application
Low-modulus rubberized asphalt 3720 3725 Initially recommended for rout and seal method, using a ¾ x ¾ reservoir and less over band. Now 3725, which has slightly higher resiliency properties, is the recommended sealant for rout and seal. It is also the recommended sealant for saw and seal.
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Recommended Applications
Material Mn/DOT Spec Recommended Application
Rubberized asphalt 3723 Was the common sealer for rout and seal until recently (Now 3725) Good adhesion qualities Used for rout and seal in situations where wider reservoir widths are needed This product can also be used for the clean and seal method
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Recommended Applications
Material Mn/DOT Spec Recommended Application
Crumb Rubber 3719 Very effective for clean and seal method Works best in the early spring or late fall when the cracks are open Although will crack in the winter, it will re-heal during warmer weather A double jacket melter is needed to maintain proper temperature of the product during application
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Recommended Applications
Material Mn/DOT Spec Recommended Application
Asphalt Emulsion CSS-1 CSS-1H CRS-2P HFMS-2 Used as a crack filler Emulsions are 33 water will shrink with curing Limited to use in warmer seasons
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Recommended Applications
Material Mn/DOT Spec Recommended Application
Asphalt Cement AC-3 Air blown asphalt used as crack filler Will get quite brittle in the winter Will track in warmer weather Discouraged by Mn/DOT
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Recommended Applications
Material Mn/DOT Spec Recommended Application
Cutback Asphalt RC MC SC Crack filler Not as readily available Not as safe as emulsions, but can be used in the winter months