When we talk about asphalt paint we can be discussing three distinct possibilities. The first of these are called asphalt waterproofing paints and are used for sealing against moisture as the name implies. The second class is asphalt coloring paint which is most noticeably used for striping on roadways and parking areas. And lastly, asphalt sealer paint is not really a paint at all but instead is intended to be placed on the surface of a road, driveway, or parking area which is constructed of asphalt as it is designed to seal surface against water.
Asphalt was originally harvested out of vast lakes such as the Le Brea Tar Pits in Southern California. It is a very viscous, which means thick, liquid at normal temperatures and it is very sticky which is why it is used as a material for constructing roads and as a sealer. When used in the construction of roadways the asphalt is used as a cement to bind the aggregate (gravel) together to form one long monolith. The strength of the driving surface comes from the interlocking of the gravel when it is compacted but the asphalt is important to keep the gravel pieces in place.
Now most asphalt is obtained by the “cracking” of crude oil. This is an action by which the raw crude oil is heated and placed under a vacuum in a tall refining vessel. Different products are removed at different levels of the vessels. These include such things as diesel, gasoline, propane, and chemical feed stocks. The asphalt component is removed near the very bottom because it does not vaporize like the others. You can think of it as the gooey mess that is left over from process. Although a technically a liquid, it is not very easy to pour at room temperature.
Asphalt Waterproofing Paint
Asphalt Striping Paint
Since asphalt is a petroleum product it is very difficult to find a colored paint for asphalt that will stay on the surface for any length of time. Any water based paint such as latex will tend to peel up quite quickly. Federal and State highway departments are constantly on the look out for new mixtures to use for the stripes that are added as traffic control on roads and highways. It must be a material the will adhere to the surface but also be able to stand up the constant abuse of thousands of car and truck tires crossing it. A relatively new ingredient in striping paints is reflective materials that make the lines easier to see no matter what the weather.
A new polymer product has been used successfully on areas such as play grounds that are constructed of asphalt if a large area is to be painted. This paint will adhere and can come in a wide array of colors.
Asphalt Sealer Paint
While not technically a paint this product is very important for sealing the top surface of asphalt from water which can seep in through small cracks in the surface to cause damage. Water expands when it freezes and thus if it gets into the structure of the roadway and then turns to ice due to cold temperatures it will slowly cause the aggregate to break apart and eventually a pot hole is exposed.
There are two main products which are used for this application. The first is asphalt emulsion which is asphalt that has been dispersed in a water base. It is rolled onto the flat surface and then as the water evaporates it adheres to the original roadway or other asphalt surface forming a waterproof barrier. Since asphalt is petroleum you wouldn’t think you would be able to mix this oil product and water but it is done with a special process that causes the asphalt particles to stay suspended which allows for the equal distribution over the surface. There are no harmful gasses as the sealer cures because the evaporating water is what is gassed off leaving the asphalt to bond to itself and the surface that is being protected.
If you are needing a driveway sealer then an asphalt emulsion can be a very effective product for the home owner. It does not require special equipment such as heating like you find in road building.
The second product comes from the manufacture of coke for the steel making industry. This coal tar as it is called is very sticky and works well as a sealer. The main problem is the amount of Volatile Organic Compounds that are found in this product which must be gassed off as it cures. These are known pollutants and have been linked to the green house effect.
As you can see there are many different meanings for the term asphalt paint. All of them are legitimate but you need to be sure you are exploring the one you want when buying a product. For example, if you were looking for asphalt striping paint and instead bought asphalt waterproofing paint, you wouldn’t be very happy with the results.
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