Posted by M Bedolla | Posted in environment | Posted on 15-01-2012
Tags: environment, environmentally friendly, maintenance, organic volatile compounds, VOC's
If you have an asphalt based driveway sealer than it is important to seal it every three or four years. If you don’t you run the risk of water seeping into cracks and causing damage. When you see a pot hole in an asphalt roadway this is exactly what has occurred. Water seeped into the asphalt layer and caused failure.
This can happen in two ways, first, if you live in a northern climate where it freezes the water can actually turn into ice and expand. When this happens it forces the crack open even wider. This starts a domino effect where by the crack gets wider so more water enters and freezes making the crack wider again.
The second problem can occur whether you ever have freezing weather or not. When the water seeps through the crack is will liquefy the substrate under the asphalt layer. This removes the benefit that this hard packed layer of gravel provides to keep the asphalt firm. As cars drive over this spot they cause the asphalt cement bond with the aggregate (gravel in the mixture) to fail and thus you have a pot hole again.
Driveway Sealer Choices
For years, the best driveway sealer was coal tar. This is a by product of the manufacture of coke which is used for making steel. Coal, under heat and pressure, is converted to a more dense energy source and a liquefied hydrocarbon is left as a waste product. This is coal tar.
Coal tar works very well as a sealer because it is sticky and bonds with the existing surface. The problem is, coal tar has a very high VOC (volatile Organic compound) rating. These are the gases that are given off when the tar cures. These are very dangerous and have been linked to cancer and respiratory problems. Consequently, this product has been banned in many municipalities.
The next best driveway sealer is an asphalt emulsion. It is much safer than coal tar but it does not last as long when applied. Since the asphalt is emulsified in water, the water is what evaporates which means there are no VOC’s to gas off. Since coal tar is no longer available this will probably be what you will need to use.
There is a third option that is just now coming on the market. Latex based sealers are now being sold in many big box home improvement stores. These products seem promising but they haven’t really been around long enough to really determine their longevity.