There are a series of procedures that must be completed before sealer can be applied to the asphalt surface. We must first check the condition of the asphalt. Depending on its condition we may need to fill cracks, replace asphalt due to pot holes and alligatoring, treat oil spots and clean the pavement with a push brush, sweeper, or pressure washer. Remember a good sealcoating job is 95% surface preparation.
CURING OF ASPHALT PAVEMENTS
The asphalt pavement must be cured, firm, and sound, prior to sealing. There are some simple tests which can be used to determine whether the pavement is cured and firm. Pour some clean water on the surface of the asphalt; if an oily film appears in the water, the pavement is not sufficiently cured. For firmness, press a screwdriver onto the asphalt surface; if the screwdriver easily makes a depression, then the surface is not set firm enough.
The length of time for curing of an asphalt pavement will vary according to the mixes used and the compaction of the asphalt. This can vary from 30 to 60 days. It will be necessary for the applicator to learn what types of mixes and meth- ods of compaction were used on new pavements. From this, a proper judgment can be made as to how long to wait before sealing a new pavement. If the size of the stone increases and heavier, compaction is employed, the pavement will be ready for sealing sooner.
This general rule applies to a plant mix type asphalt pavement. A pavement which is made of cold mix, or by shooting and chipping, will take one to two years before it is cured sufficiently to seal with a coal tar emulsion.
Blocking off of pavement should be accomplished with as many bulky items as possible. Then twine should be stretched between the barricades at a height of 28 to 32 inches from the ground. Flags can be tied to the twine to make it more visible. Blocking cones can be used, but are not as effective unless a great number of the large variety are used. People generally know they can drive over them or between them.
CLEANING THE ASPHALT PAVEMENT
The cleaning and preparation of the pavement is a most important function for getting good applications. When
the repairs are complete, the pavement must be cleaned of all oily substances and all dirt. The oil and grease spots must be cleaned and scraped to remove as much of this material as possible. These spots should be then treated with oil spot primer and brushed into the effected area and allowed to dry. Then the entire area must be clean of all dirt. This can be accomplished by the use of the air broom. The air broom should be operated to blow dirt from the wind; however, try to blow the dirt away from the buildings, traffic, and pedestrians. On large jobs, start in the area where you plan to seal first and continue in a systematic manner across the pavement. Areas will be encountered where dirt and silt are stuck tight to the surface. These will be around the perimeter of the pavement and in areas where water stands. Use the wire broom to brush away these areas while the air broom blows away the dirt. If the loose material begins to build up, remove this with a scoop shovel and the cleaning will go along more quickly. If any areas appear to have silt embedded in the pavement that cannot be blown and brushed off, these should be cleaned with water pressure. All growth dug loose from the edges of the pavement (dirt and stone) should be hauled away or deposited in the owner’s trash container (with the owners permission of course). Wet spots can be dried with the help of the air broom, or by brushing the water around with a street broom. By spreading the water around in this manner, it will dry more quickly.