Hairline cracks--Cracks that are 1/8 inches (3 millimeters) or less in width are too small to seal effectively. If there are numerous hairline cracks over a large area, then a surface seal such as fog seal, chip seal, slurry seal or sand seal should be used. The particular surface seal must be fluid enough to flow into the all the hairline cracks.
Small, medium and large cracks---Cracks that are 1/8 inch or slightly larger are usually routed to a width of inch or greater to provide a reservoir for the sealant. The crack is then cleaned and sealed. If the cracks are more than 2 inches deep, a backer rod should be installed to conserve sealant.
Cracks that are ½ inch to ¾ inch wide usually need only cleaning and sealing. Install a backer rod if cracks are more than 2 inches deep. Cracks that are larger than 3/4-inches wide should be filled with an asphalt emulsion slurry seal, a hot mix asphalt sand mix, or a hot-poured sealant.
