What is Sealcoat?
Coat is a mixture of emulsified asphalt, water, mineral fillers, and
various other mixtures. Seal coats are applied directly to the surface
of an asphalt pavement. It can be applied by rubber squeegee, broom, or
Seal coat serve to seal the top of the asphalt, preventing water from penetrating the surface of the pavement and protecting the top layer of asphalt from oxidation and wear caused by exposure to the sun and air. Seal coat also beautify the pavement by providing a smooth, black, even surface ideal for painting lines and sweeping.
Seal coat is designed for off highway use where there are low traffic speeds and tight turning radiuses such as parking lots, mobile home parks, schools, shoulders, etc. Seal coats are different from slurry seals which use a much coarser aggregate filler and are designed for use on high speed areas with straight rolling traffic.
What Causes Asphalt Pavement to Fail?
Assuming that the initial asphalt pavement was designed and constructed properly, the primary cause of failure is the penetration of water into the asphalt base.
This process begins with the oxidation of the pavement surface which caused the asphalt to dry and become brittle, this leads to the erosion of the top layer of fine particles and the appearance of larger stones and small cracks on the surface.
If left untreated these cracks grow over time and eventually allow water to penetrate to the base of the pavement. When water enters the base of the pavement the base material moves and settles leading to further cracking and an "alligator appearance."
When the pavement reaches this stage the only option is removal and replacement of the old asphalt.
How does Seal Coating help?
Seal coat seals the asphalt pavement, preventing the oxidation and erosion of the top layer of asphalt. On older pavements seal coating replaces fine particles lost from the asphalt surface due to oxidation. Seal coat seals the small cracks that can turn into large cracks and prevents water from seeping down to the base material.
Seal coat helps protect the asphalt from the sun as well as the harmful effects of chemical spills such as oil and gasoline. Seal coating provides an attractive black surface that is ideal for painting lines and other markers. It also leaves a smooth, clean surface ideal for sweeping, lowering cleaning costs. Seal coat costs pennies per square foot compared to the dollars needed to repair or replace damaged asphalt.
When Should Seal Coating be Done?
Generally you should wait a few months before sealing new pavement to allow it time to cure. CSI recommends waiting 6-12 months before seal coating new pavement.
After a surface has been sealed it should be re-sealed every 3 - 4 years or as necessary.