There’s a saying among true professional sealcoating contractors: “Good sealcoating is 95% surface preparation”. Be sure your seal coat contractor is meticulous about surface prep. Here are some examples of important factors:
ASPHALT PAVEMENT CURING
Asphalt must be cured and solid before sealing. There are very simple tests which can determine whether the pavement is sufficiently cured. A contractor can pour clean water on the surface of the asphalt in question. If an oily film appears in the water, it means the pavement isn’t ready due to insufficient curing. To test for firmness, a contractor may push a screwdriver onto the asphalt surface. If it’s easy to make an impression in the surface, this indicates the surface isn’t firm enough and needs additional cure time.
Asphalt pavement cure time varies according to the compaction and mixes of the asphalt. Believe it or not, this can vary greatly–from 30 to 60 days. Your contractor should learn which types of mixes and compaction methods were utilized on new pavement in order to make a correct assessment as to how long to wait before sealing. If stone-size is increased and heavier compaction is used (such as in plant mix type asphalt pavement) this will cause the pavement to be ready for sealing sooner. However, if a pavement is made of cold mix or by “shooting and chipping”, this will take 1-2 years before it’s cured enough to seal with a coal tar emulsion.
It’s important to block off pavement with barricades. Twine should be attached between 28″ and 32″ from the asphalt. Contractors may attach flags or ribbon to make the twine more visible. Cones are often employed and are more effective with increased number and variety so people aren’t tempted to drive over or between them.
It’s utterly important to clean and prepare the pavement to get good applications. After repairs have been completed, the pavement should be cleaned of all the oily substances or dirt present. Oil and grease spots should be scraped and cleaned to remove as much excess material as is practical. Oil spot primer can be used and brushed into these spots and should be allowed to dry. After spot-cleaning, the entire area should be cleared of dirt, often accomplished by use of an air broom (which should be operated to avoid buildings and pedestrians).
On bigger jobs, the contractor should start where he/she plans to begin sealcoating. If dirt or silt is stuck tight to the surface (this especially occurs around the pavement perimeter and in areas where standing water is presnt), a wire broom canb e used to brush away these areas and an air broom may be used to blow away the dirt. In particularly stubborn areas, a scoop shovel and even a pressure washer may be required.
Once all areas are fully cured, barricaded, and cleaned, your asphalt is well on its way to true professional sealcoating.