Maintaining your asphalt is a necessity if you want to keep it aesthetically pleasing and well-preserved. A proper maintenance program includes crack filling, pothole repair, sealcoating, and a multitude of other surface applications. What your asphalt receives will be dependent on it’s existing condition. While maintenance plans may vary the goal never changes: to increase pavement life.
In order to fully comprehend how sealcoating benefits asphalt you are going to have to understand exactly how asphalt works. The reason it has been used extensively for paving and road construction is due to its waterproofing, flexibility, and adhesive properties. Prior to using asphalt as a paving material, roads were mainly made up of graded aggregates over a roadbed. Not only did this method require constant repair, but the stone would shift under traffic and its carrying capacity was severely damaged after it rained. Water would absorb into the stone causing it to swell and lose its strength. The problem was somewhat overcome by spraying asphalt on top of the surface.
You may be asking, “So why seal asphalt?” Well, because despite the several positive qualities that asphalt contains there are some serious drawbacks. Said drawbacks relate to its chemical makeup. This chemical makeup allows easy access to weather, salts, and substances to attack and disintegrate the molecules. As the molecules began to break the asphalt starts to lose many of its desirable properties, such as waterproofing and binding. The first sign of this process will began with the rich black changing colors to brown to gray.
Benefits of Sealcoating: I guarantee you that the benefits of sealcaoting will greatly outweigh whatever doubts you may have.
Appealing: When applying fresh sealcoat it will bring a dark black color to the pavement, when doing so it will look and wear just as it would if it were brand new. This will present a positive image of the company, facility, or residential complex.
Reduction of Water and Oxygen Exposure: Another thing to keep in mind is that when asphalt is exposed to oxygen it will harden its binders and cause it to become brittle that cracks easily. Water can leak into said cracks and penetrate into the sub base, weakening it and reducing pavement strength. The cracks that once seemed small and insignificant will eventually expand and turn into potholes. By sealcoating you will be prolonging your pavement life by filling the surface voids, reducing exposure to oxygen and water.
Less Gas and Oil Damage: When gasoline or oil comes into contact with asphalt it will penetrate and soften it. Coal tar sealers will prevent this damage because coal tars aren’t soluble in gas or oil.
Easier to Clean and Maintain: When sealcoating the surface voids that cover the pavement surface will be filled resulting in a smooth more even surface texture. This smooth surface will ensure that you are able to maintain your pavement year-round. For example, snow is easier to remove and sweeping is more effective.
Pavement Flexibility Increases: Due to the black color that sealcoat gives your pavement it will absorb a significantly more heat then if no sealcoat was applied. The more heat it draws, the more pliable it is, the more able it is to withstand traffic volume changes without cracking.
Cost-Effective In The Long Run: It’s less expensive to sealcoat a parking lot every couple of years using a coal tar or asphalt emulsion than it is to overlay or place a new lot.
However, there are preparations that need to be made before asphalt can receive a sealcoating treatment. There must be at least a 30 day gap from when new pavement is laid down to when sealcoat is applied. When applied too soon the sealer may trap asphalt volatile at the asphalt/coal tar interface, softening the surface below the sealcoat. This might result in flaky or peeling sealcoat.
When dealing with old asphalt small cracks must be cleaned and the larger ones should be filled with crack sealant. Oil spots are to be removed or treated with oil spot primer to increase adhesion. If there are patches of asphalt that contain alligator crackling they may need to be removed or replaced. If any depressions are present they will have to be brought up to grade with hot mix asphalt and allowed to cure. Once all repairs are completed all dirt and debris need to be cleared from all areas that will receive sealcoat. The reason for this is because dirt reduces the bond between sealcoat and pavement. The sealer will adhere to the dirt but the dirt won’t adhere to the pavement. On top of all this pavement that is overly dried out, it will be light gray in color, may require primer to improve sealcoat adhesion. The primer should be diluted with five parts water to one part emulsion. It should then be applied with brush or spray at a rate of approximately 1 gallon per 100 sq. ft.
Weather plays an important part in when sealcoat can and can not be applied. If the air temperature is above 90 degrees Fahrenheit then the asphalt surface should be sprayed with a fine mist of water. There should be puddles or visible water. Not only that, but sealcoating should only be performed under proper conditions. 50 degrees Fahrenheit is the recommended temperature for the time sealcoat is being applied and at least eight hours afterwards.
There is a system to applying sealcoat. More often then not two coats will be put down. All air pockets and ridges should be gone after the first coat is applied. When that drys and is thoroughly cleaned the second coat will be put on at right angles to the first. The reason for this is to enhance bonding between both coats.