The main causes of sealcoating wearing prematurely is vehicular traffic, snow plowing and heavy sanding. If sealcoating is applied properly the sealer will wear gradually. First in the areas of heavy traffic such as travel lanes and then in the rest of the asphalt area such as parking stalls. Premature wearing, flaking or peeling of the sealcoating application may have been caused by several reasons that could have been easily prevented.
The most obvious reason for premature wearing is A lack of proper cleaning. The use of a sweeper or blower alone in most instances will not get the asphalt clean enough to properly apply sealcoating materials. In conjunction with the blowers and sweepers, scraping and heavy brushing with brooms and wire brush machines is needed to get the dirt that is ground into the pavement or in the pores off the pavement. In some instances that is not enough, and the use of a pressure washer will be needed. If the cleaning process is done correctly it may be more difficult and take longer than the actual sealcoating application. The cleaning process is one of the most important elements of sealcoating projects. If the pavement is not cleaned properly the sealcoating will have difficulties.
The second most common reason for sealcoating to prematurely wear is the pavement is too oxidized or polished, for the typical sealcoating application to bond properly. If your asphalt is light gray or you can actually see the aggregate (stone), there will be a bonding problem. This type of asphalt is called polished, which means that with exposed aggregate the pavement is too smooth or slick for the sealcoating materials to bond properly. This kind of situation would be like trying to get paint to stick to a mirror or ice.
The amount and location of the polished asphalt in a parking lot is in direct proportion to the amount of traffic and turning in each area. The more traffic and turning on the pavement surface the more polished the asphalt. The most polished areas in a parking lot typically are the exits, entrances, turning areas and travel lanes.
Sealer in these polished areas will wear off the surface prematurely if the surface is not pre-treated prior to the sealcoating being applied. Specialty primers such as polyprime from Neyra Industries have been designed to penetrate the aggregate and provide a more suitable surface for the sealer to bond to. The entire parking lot does not have to be treated with primer. In most cases just the travel lanes need to be primed prior to the sealcoating. Once the primer is applied and dry, the sealcoating can then be applied. This all can usually all be done on the same day.
Pavement that is heavily shaded by trees is also sometimes a bonding issue for sealcoating. These areas are very frequently common locations for flaking, peeling and premature wearing of sealcoating. During warm weather, sap and fluids drip from the trees onto the pavement. The tree drippings are full of minerals and sugar. The sugar alone is water soluble and if sealed over will come up through the sealcoating causing lifting and flaking of the sealcoating material. The solution is prior to the sealcoating, power wash the areas under trees where there is heavy shade removing sap, and fluids that have accumulated.
You may also notice the sealcoating coming off where white or brown streaks are occurring. These streaks are usually coming out of cracks or alligatored areas. The streaks were there prior to the sealcoating but are typically not visible because they blend in with the oxidized gray color of asphalt. Typically, it is a water problem in the base that causes these streaks. Water with limestone residue is bleeding up through the cracks causing the sealcoating to lift. There is no way to stop this unless the base and water issue is resolved. If lucky, the answer is simply removing and replacing the base and existing asphalt. The solution in some cases; may not be that simple and the water issue may have to be corrected by a drainage system, which is typically expensive. The only actual way to solve this issue is to stop the water from pumping up through the asphalt.
Mold and mildew growing on the pavement is another issue for sealcoating. This gray or green material is often found in the shaded areas close to the building, under trees or other areas that stay damp for long periods of time. There will most often time be green or gray matter growing on the pavement in shaded areas close to the buildings or under trees along with areas that are damp and take a longtime to dry. You cannot just blow this growth off of the asphalt, and in most instances just like when painting your house these areas need to be power washed clean to ensure the mold and mildew is completely removed from the surface and in any pores.
When painting your house, rotted wood is always a problem and paint cannot stick to rotted wood for very long. An oil spot on an asphalt is the rotted wood of a parking lot. If the oil stain is just minor and has not damaged the asphalt the solution is a simple one. The oil spot can be prepared by lightly heating, scraping off the residue, cleaning and applying an oil spot primer. Then an application of sealcoating material can then be applied over it. The oil spot primer can only go so far though and If the area is saturated with oil and the asphalt is unraveling there is no amount of oil spot primer in the world that will fix it. The test to simply tell if an oil spot is too far gone for oil spot primer is a screwdriver. Push the screwdriver into the asphalt. If it sinks into the asphalt or you can loosen the aggregate up, the spot is too far gone for primer. The only solution with this situation is to cut the area out and replace it with new asphalt or to Infra-Rad the location. This tends to be expensive and the decision must be made whether it is worth the money spent. The question is, will the area repaired soon be re-saturated and damaged by the constant dripping of oil?
These are just a few of the most common instances where premature wearing and flaking of sealcoating occurs. In most instances if you have contacted a reputable sealcoating company, they will point out any bonding problems your parking lot may have. They will then recommend solutions how to solve these issues and you have the choice as to what the best course of action is for your pavement.