If you need a driveway, parking lot, or road, you have probably considered asphalt paving. Asphalt is a wonderful paving material because it is durable and can be laid smooth. Yet you may not have given thought to what asphalt actually is or where it comes from. Here are some fun facts about asphalt.
Asphalt Is Natural
Asphalt is based on a naturally occurring material called bitumen, which is a tar-like petroleum substance. Natural aggregates such as crushed rock, gravel, or sand are added to the mix.
Asphalt Is Ancient
Ancient peoples first used natural asphalt for waterproofing. It was used for roads by at least 625 BC, and was an important trade good in ancient Egypt, where it played a role in mummification.
Asphalt Is Poured Hot
Asphalt is poured hot because at high temperatures, the bitumen flows like a liquid. This allows it to fully coat the aggregate, and to be spread, rolled, and compacted to a smooth, durable surface.
Asphalt Is Viscoelastic and Flexible
Asphalt is considered a viscoelastic material, as it has properties of both a viscous material and an elastic material. It is flexible and actually moves under heavy loads. Asphalt will generally rebound to its original shape after the load has passed. However, if a very heavy load such as a tractor trailer remains for a long time in high heat, the asphalt could actually become rutted. This means that it is too compacted and can no longer regain its original shape. You can see this sometimes in truck parking lots and near traffic lights that have frequent truck traffic.
Not All Asphalt Is the Same
Asphalt binders are rated on a lab-tested scale known as the PG scale to determine the temperature range in which the binder performs well. The wider the range the better, but also the more expensive. To increase the range, asphalt plants often add polymers that boost strength and flexibility.
Paving Asphalt Must Be Carefully Handled
Paving asphalt is generally made in an asphalt plant, where the precise mix of ingredients can be carefully regulated. It is then delivered from the plant to the job site in special asphalt trucks that keep it at the desired temperature. When the trucks arrive at the job site, the drivers slowly lift their truck beds to pour the asphalt. They must take extreme care to pour at just the right rate or the asphalt could cool before it is spread, rolled, and compacted.
This is a particular concern during cooler weather, so non-emergency asphalt jobs are not typically performed during the winter months. If an emergency arises during wintry weather, cold patches are available. These will last until a proper repair can be made in the spring, but are not designed to permanently replace hot mix asphalt.
Ready to Get Started?
Are you ready to start your next asphalt project with a team you can count on to do the job right, on time, and on budget? Contact TopWest Asphalt today at 1-800-ASPHALT to discuss your project and schedule an estimate.