As a property manager, you have a responsibility to not only maintain the infrastructure of your buildings, but their parking lots as well. However, without any construction experience, you're wondering why your asphalt lot seems to require seal coating or crack sealing much more often than it should. Instead of continuing to pay hundreds of dollars every few years, take a moment to learn how these three problems damage your lot.
Although your asphalt may have a sealed surface, rainwater and other forms of moisture (such as dew and gutter runoff) will seep into the tiny indentations throughout your asphalt surface. Although water doesn't initially cause any damage, it becomes problematic once it manages to force its way through the top seal of your asphalt surface.
The most common way for water to seep through your top layer of asphalt is by freezing. When water freezes, it expands. The water that settles in the top layer of your asphalt lot will place pressure on the rocks in your asphalt and tear apart the oil compounds that act as glue.
As this process repeats itself all winter long (or all year depending on your local climate), it gradually increases the size of the indentations in your lot. As gaps and holes in your top layer of asphalt grow in size, more water is able to enter them—which will only compound the damage to your lot. Over the course of a few months, water damage can turn a barely-visible indentation into a wide crack or pothole.
There are several ways to prevent water from excessively damaging your lot. However, timing is key. Walk throughout your lot once a month to identify any newly-formed cracks. Either physically mark the cracks with spray paint or mark them in a diagram of your lot. Perform or arrange for crack sealing to prevent water from gradually ruining your lot. Crack sealants are made of a rubber compound that expands as it dries, which allows it to completely fill your lot's cracks.
Those signs lining the sides of your city roads that indicate the maximum vehicle weight for the specified road are there for a reason. Similarly to your city streets, your asphalt lot was only designed to withstand a limited amount of weight.
If vehicles such as semis or large trucks with heavy trailers frequently use your lot, then their weight can easily overpower the strength of the oil compounds that hold your lot together. If this is happening with your lot, then you'll see grooves running throughout your lot's main lanes and intersections.
The best way to prevent overweight vehicles from damaging your lot is to install signs that notify drivers of the maximum vehicle load for your lot. Weight limit signs should be posted at all entrances to your lot to allow the drivers of overweight vehicles to find an alternate parking spot or route. To ensure these signs are followed, consider hiring a lot attendant if you don't already have one.
Both water damage and overweight vehicles can wreak havoc on your lot's lower layers.
Beneath your lot's surface and base are two additional layers called the aggregate and subgrade. Your lot's aggregate consists of loose stones that are readily capable of draining water that leaks beneath your lot's surface layers. Your subgrade consists of organic matter, clay, silt, sand, or gravel and bears the weight of all other surface layers.
Although these lower layers of your lot aren't visible, they can still cause visible problems. If your aggregate layer becomes compacted (which will happen when overweight vehicles drive through your lot), then water can become trapped inside your layers and seep into your subgrade. If your lot's subgrade consists of a soil type that cannot remain thoroughly compacted while wet or under heavy load, then it will become displaced.
When these two layers experience these two problems, the upper layers of your lot will sustain heavy damage. When a vehicle drives over an area of your lot where your subgrade layer has been partially displaced, then your upper layers will collapse.
If your lot's lower layers are compromised, then the best way to minimize future damage is to replace your subgrade layer with gravel or sand—the two soil types with the highest CBR ratings. Once your subgrade is replaced, your other layers will be able to withstand greater wear and tear with ease.
Now that you understand how these three problems affect your asphalt lot, you can take the necessary precautions to reduce future damage. However, if you're unable to seal your lot's cracks or determine the weight limit of your lot, then hire a professional asphalt maintenance contractor to do the job for you.