Crack Sealing - For Over 35 Years
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Crack sealing prevents the first small cracks that form in an asphalt pavement from spreading across the surface and deepening to the lower levels of asphalt. When the cracks deepen, water gets into these lower levels and structurally undermines the base and subbase, creating a much larger and more expensive problem than the small cracks posed initially. Crack sealing keeps the small cracks from creating these big problems. It also keeps dirt, stones and other particles from getting into the cracks and causing compressive stress. As with all asphalt maintenance procedures, crack sealing will save you money in the long run. When you crack seal your pavement, you extend its life for 3 to 5 years and delay an expensive resurfacing or overlay, procedure.
There is a difference between crack sealing and crack filling. Crack sealing is less expensive and longer lasting than filling. Filling can't expand and contract with the pavement during freezes and thaws the way a rubberized asphalt sealer can. A rubberized sealer will adhere to the sides of the cracks and move with the pavement's expansions and contractions, preventing re-cracking and consequent water infiltration.
If you plan to sealcoat your asphalt pavement, which is another highly recommended maintenance procedure that significantly extends the life of your asphalt pavement and saves you money (see our page on sealcoating,) you must repair any cracks or potholes in the road first, so crack sealing will be a must.
There are seven different kinds of cracks that can appear in your asphalt pavement, some of which can be repaired with crack sealing and some of which cannot. The cracks for which sealing is an effective repair are: block cracks, longitudinal or joint cracks and transverse cracks. Cracks that can sometimes, but not always, be repaired by crack sealing include edge cracks and reflective cracks. The cracks that cannot be repaired by crack sealing are fatigue or alligator cracks and slippage cracks. See below for more information.
Block cracks roughly form the shape of blocks on the pavement surface. These cracks are usually caused by contractions of the asphalt during cold weather combined with hardening of the asphalt due to old age. They can also be caused by low-flow traffic, because regular traffic flow produces even, regular pressure on the asphalt that keeps it relatively elastic rather than stiff, brittle and susceptible to cracking. Block cracks can be caused by other factors as well, including an excessively high temperature for the asphalt mix, too many cavities caused by air pockets, or low-penetration asphalt. Crack sealing is an effective repair for block cracks.
Longitudinal or Joint Cracks
Longitudinal or joint cracks run roughly parallel to the pavement edge, and they often form where two slabs of pavement meet each other, at the joints connecting them. The cracks tend to form here because the joints between the two pavements are usually made of lower density asphalt than the pavements themselves. Longitudinal cracks can occur when the two pavements don't join like they're supposed to. They can also be caused by traffic loadings or thermal stress. Crack sealing is an effective repair for longitudinal or joint cracks.
Transverse cracks run perpendicular to the edge of the pavement. They are caused when the asphalt contracts in cold weather. Crack sealing is an effective repair for transverse cracks.
These cracks occur within 2 feet of the edge of a paved road that runs along an unpaved shoulder. The cracks look like crescents or form continuous lines parallel to the edge of the pavement. Edge cracking includes longitudinal cracks (see below) that are also within 2 feet of the pavement edge, outside the wheel path. Causes of edge cracks include lack of shoulder support, overloading on the pavement edge, frost, erosion of the shoulder, insufficient drainage and a deficient asphalt base. Crack sealing cannot always repair edge cracks.
Reflective cracks may look like any of the other types of cracks listed here. They usually occur during or after asphalt resurfacing, or overlay. In resurfaced asphalt, reflective cracks are caused by existing cracks in the underlying asphalt surface that cause new cracks to form upwards through the overlay. This happens due to movement of the asphalt at the crack. The result is cracks in the overlay that are like reflections of those below in the old asphalt. Reflective cracks sometimes occur in new pavement, too. A crack in the base below the new asphalt will cause the same kind of reflective cracking as in the case of overlay. The proper repair for reflective cracks depends on the initial cause of stress.
Fatigue or Alligator Cracks
Fatigue or alligator cracks are more serious than the other types listed here and may require removal and replacement rather than crack sealing. Fatigue cracks are often referred to as alligator cracks because their intersecting lines form a pattern of small blocks on the asphalt surface that look like an alligator's skin. Fatigue or alligator cracks are primarily caused when an asphalt pavement ages, the asphalt binder breaks down and the asphalt itself becomes less flexible and more brittle, making it susceptible to this type of cracking. They can also be caused by oxidation or structural defects. Sometimes fatigue cracks develop from longitudinal cracking in the wheel paths of a road. Left untreated, fatigue cracks can turn into pavement disintegration and potholes.
Slippage cracks result from strains on the asphalt caused by high-flow traffic. These strains weaken the bond between the upper and lower layers of asphalt. This causes the top layer of asphalt to shear, and the resulting cracks look like crescents. The open end of the crescent points in the direction in which the force of the vehicles is applied to the asphalt. Slippage cracks cannot be repaired with crack sealing.
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Thank you for an excellent job.