Why seal an Asphalt driveway?
It is very important to use an asphalt sealer on your driveway to prevent damage caused by sunlight, rain, and snow. A new, unsealed driveway will be fine for a few years, but neglecting to apply asphalt sealer to the surfaces of your property allows water to sneak beneath the porous surface. When the water freezes, heats up, or saturates the soil underneath the pavement, you will start to see cracks. Your only choice at that point would be relaying the asphalt.
Another reason you might consider it important to use asphalt sealer is to maintain the original, dark color of your driveway. The sealer will keep your asphalt black, rather than letting sun and traffic dull it to a faded gray. Asphalt sealer can also resist spills from car oil and other maintenance fluids that you don't want to stain your driveway.
If you owned a parking lot, you would have another reason to use asphalt sealer. The constant friction of tires will wear away the uppermost layer of asphalt. This layer has a lot of gummy petroleum material and not as many aggregate rocks. Once it wears away, the erosion of the parking lot will speed up. A thinner asphalt is even more likely to crack, buckle, or develop potholes.
What causes Asphalt damage ?
Cracks in asphalt occur when the earth underneath the pavement shifts for some reason. This could be due to seasonal changes in weather and humidity. Asphalt is designed to resist this moisture penetration, since it has glue keeping the aggregate material together. Even still, asphalt is not impermeable to water damage, especially in a driveway.When cold water sinks into or below the asphalt, it will freeze when temperatures drop. Freezing water expands, interfering with the stickiness of the glue. At some point, the water defrosts and shrinks, putting structural strain on the pavement. Pavement may buckle and make small fissures or larger cracks.
How often should I seal my driveway?
After the initial base application, your driveway should be sealed every 2-3 years depending on personal preference.
General rule of thumb is NOT to seal your driveway every year!!! Sealers are coatings, just like paint. You can easily apply too much and the coatings will begin to crack and peel. Only reseal the driveway after you can clearly see that the old sealer is wearing. When the color of the aggregate (rocks) begins to show, it is time to reseal.