1. Crack Treatment Sponsored by: Minnesota LTAP Center Presented by: Michael Marti, P.E. SRF Consulting Group, Inc. Dan Wegman, P.E. SemMaterials

2. 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.

3. 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.

4. 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 manufacturer’s recommendations for sealant application

5. 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.

6. 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.

7. 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.

8. 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.

9. 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.

10. Recommended Applications Material Mn/DOT Spec Recommended Application Rubberized asphalt 3723Was 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

11. Recommended Applications Material Mn/DOT Spec Recommended Application Crumb Rubber 3719Very 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

12. 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

13. Recommended Applications Material Mn/DOT Spec Recommended Application Asphalt Cement AC-3Air blown asphalt used as crack filler Will get quite brittle in the winter Will track in warmer weather Discouraged by Mn/DOT

14. 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