What Causes Cracks in Asphalt Paving?

Asphalt paving provides an affordable, safe and attractive surface for your driveway. But cracks and other marring detract from the appearance and cause premature deterioration. Homeowners wonder what causes cracks in asphalt paving and what can be done to avoid this issue?

Three Main Causes

Cracking is most often the fault of one of these three common culprits:

  • Moisture - powerful and persistent, water begins to break down a paved driveway almost immediately. Moisture washes away the gravel and sand base of an asphalt drive, causing the surface layer to shift and break, resulting in cracks of varying sizes. Water also attacks from the top, finding its way into crevices, creases and dents and exerting pressure from above. The weight and movement of rain water and snow will wear at the paved surface over time.
  • Sun - another powerful force of nature, the sun beats down on asphalt, creating heat and breaking down the substances contained in this aggregate material. Sunshine dries up the surface, and although too much moisture causes asphalt to wear down and crack, not enough moisture creates similar results. As the components of asphalt break apart under the heat of the sun, cracking results from normal conditions, such as a parked car, basketball net or even foot traffic.
  • Ground Movements - the ground constantly shifts due to seasonal conditions such as frost and thaw. Disasters like earthquakes and major storms also cause the earth to shift, but it is the annual ground movements that have a greater effect overall. Asphalt driveways are installed on a bed of gravel spread across graded earth. When that earth moves, the gravel naturally moves and puts force on the asphalt, often resulting in cracks and/or potholes.

What About Crocodile Cracking?

Crocodile cracking or alligator cracking is a common problem in driveways and paved areas. According to web sources, the main cause of crocodile cracks is traffic loading, making it more an issue in parking lots and roadways. Keeping your vehicles in the garage helps to reduce the risk of this problem. It is also wise to routinely move heavier vehicles and equipment (such as trailers and RVs), distributing the load to avoid major cracks.

Sealing may protect your paved driveway from this issue. Maintain good drainage and direct run off away from your driveway to maintain a stable base. Strong base layers create a more durable paved surface, even when that surface is subjected to heavy traffic loads.

Flexibility and Durability

As the National Asphalt Paving Association (NAPA) states, hot mix asphalt is designed to be flexible and withstand the pressures of a four-season climate. Concrete and premade paving stones are rigid, while the make up of hot mix asphalt allows a certain amount of give. As noted above, major ground movements will result in cracking, as will gradual, yet noticeable changes to grading of your property. But local hot mix asphalt plants will produce a mixture made to withstand the regional climate, including the shifts associated with frost and thaw.

For more information on the components included in hot mix asphalt and the importance of using a quality mix, click here.

The Age Factor

Cracks most often occur on older asphalt driveways. This can be attributed to the causes mentioned above—more exposure to the sun, greater amounts of moisture and consistent ground movements will take a toll. But aged asphalt is also less able to withstand the pressures of gravity, and it's difficult to protect your paved driveway against that factor.

New asphalt dries hard, but retains a certain amount of flexibility. As the material ages, that flexibility decreases and asphalt becomes more rigid. Gravity then takes a toll, exerting pressure on the entire surface and resulting in cracking. This often happens along the edges of your paved driveway, but can also occur in the middle sections.

Even tiny cracking presents a problem for your driveway. Moisture enters the smallest crevices, pushing down through the material and washing away the base layer, resulting in less support and greater cracking. Once a small crack appears, larger cracks will follow, especially on older driveways.

Maintenance Tips

Asphalt driveways tend to have a lifespan of fifteen to thirty years, depending on your climate, the quality of the hot mix and installation. Maintenance is also a factor. Paved driveways tend to be low maintenance, but with a few simple tasks and a keen eye for problems, your paved drive can last longer than the average driveway.

Tend to cracks as soon as possible. Crack sealants work well for small cracking, and those tiny fissures can soon lead to large gaps when left unattended. Experts recommend using asphalt crack repair products on single cracks; this approach will not work on crocodile cracking. Look for products made to withstand sun and moisture, and follow the directions with care.

Asphalt contractors will patch repair a larger driveway, although this tends to be a temporary solution. The issues that caused the initial cracking are often still present after the repairs are completed. Replacing the entire driveway, along with the base layer, is often the most straightforward and economical way to approach major crack repair.

Driveway sealants may help to protect your paved drive from the effects of sun and rain. However, many of these products simply improve the appearance of your driveway and do little to reduce the risk of cracking. Talk to your friends and neighbors before investing in driveway sealants, and find a product that offers a decent warranty.

Asphalt paving provides excellent value for any home. Inexpensive and attractive, this product creates a safe surface for foot and vehicle traffic, improves your property value and reduces maintenance overall. Various sources cause cracks in asphalt paving, and only a few are avoidable. Optimize the value of your property by taking good care of your paved driveway and attending to cracking as soon as possible.

Posted by: diana
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