When I talk to customers, the question of “what causes the most harm to an asphalt surface?” comes up quite often. While there are several things that can harm asphalt, there are three enemies of asphalt that are the most common: water, overloading, oxidation.
Water itself is not bad, but standing water on an asphalt surface
accelerates the breakdown of the asphalt. The water is absorbed into
the base layer and with cold weather, the water will freeze and thaw
which can causes damage to the asphalt. This problem can be solved by
making sure the asphalt has proper drainage by either pitching the
surface or installing some type of drain to catch the water and run it
Another enemy of asphalt is overloading. Asphalt pavement is
designed to handle a particular amount of weight. There are two
elements to the strength of an asphalt surface: aggregate base and
asphalt. Base usually consists of 6-12” of limestone aggregate and is
the back bone of any asphalt parking lot. The asphalt usually consists
of 2-4” and is the wearing surface. If too much weight is put on the
asphalt, it flexes beyond what it’s capable of and starts to crack and
rut. It’s important to design the asphalt parking area to meet the
traffic flow. A shopping center parking lot will need a heavy duty
specification for the high traffic flow, while a driveway only needs a
basic specification for parked cars. It’s important to talk to your
contractor and decide what is needed for your specific application.
The final enemy of asphalt is oxidation. Oxidation is the process of
the sun “cooking” the asphalt cement (tar) out of the surface. The
asphalt cement is what binds all the aggregate together. Not enough
asphalt cement, the stone and sand start to come apart and you end up
with just gravel. Oxidation will happen no matter what, but you can
slow the process down by seal coating your asphalt surface on a regular
basis, typically every 2-4 years. Seal coating can double the life of
an asphalt drive.
Water, overloading, oxidation are the three big enemies of asphalt.
All three can be overcome with proper planning, design and maintenance
of your asphalt surface.