What Causes Concrete and Asphalt Driveway Cracks?
Proper installation is a critical part of preventing large driveway cracks. (Photo courtesy of Angie’s List member Joe D. of Rosemount, Minnesota)
Given enough time, almost every driveway cracks when the material starts to break down and separate. But while you may find it acceptable to discover cracks in a 20-year-old driveway, cracks in a much newer asphalt or concrete driveway can be frustrating.
By understanding the reasons behind driveway cracks, you can take preventive and corrective measures to ensure your paved surface will look like new for as long as possible.
Concrete vs. asphalt driveways
Asphalt and concrete are used for the vast majority of driveways in the United States, and both can experience cracks from the same set of causes. However, because asphalt driveways are generally set up as one long, unbroken surface, they will often crack more easily than concrete surfaces, which have controlled joints interspersed throughout. Even with this propensity, when properly installed, driveway cracks of significant size should not appear for several years no matter which material you choose.
Poorly installed driveway base
The most common cause of cracks in driveways is improper installation, usually in the form of a poorly constructed base or subbase. That's why it's so important to find a reputable driveway paving company. Good concrete contractors as well as dependable asphalt companies will build a driveway subbase from crushed stone, pack it extremely tight, and then install an aggregate base, before pouring the asphalt or concrete driveway material over it.
Contractors who install an improper base or subbase, usually to save money or time, often use a light material like sand or dirt. When this loose material gets moist, the freeze-thaw cycles cause the material to expand and contract, putting uneven pressure on the driveway and causing the concrete or asphalt to crack.
Don't use salt to melt ice
Salt may be fine for gaining traction on some surfaces, but it's brutal on concrete and asphalt — which already take a beating during harsh winters due to the freeze-thaw cycles of the season. The salt speeds up the thawing process of the snow and the water will seep directly into the paved surface, where it will refreeze and exert pressure on the structure, eventually resulting in a crack.
Use sand instead of salt on concrete in the winter. The snow will stick around, but the sand will provide traction for vehicles without ruining your concrete driveway. Be wary of using any ice-melting products on asphalt, particularly if the driveway isn't properly sealcoated.
Manage tree roots
Just as the freeze-thaw cycle can cause tremendous pressure on your driveway, growing tree roots can do the exact same thing. As the roots grow, they apply uneven pressure on parts of the driveway and its foundation, eventually resulting in a crack in the concrete or asphalt once the pressure builds up past the material's breaking point.
Consider driveway placement in relation to your trees when pouring a new driveway or look into installing a tree root barrier system on the sides of the driveway to prevent those type of cracks in the driveway. But keep in mind, this can make nearby trees slightly unstable as they grow.
Limit excessive weight
Both concrete and asphalt are fairly strong materials, so you may assume they can withstand a lot without breaking. But they are far from indestructible. Just as pressure from below can crack a driveway, pressure from above can fracture the paved surface as well.
The exact amount of weight a driveway can hold without cracking varies based on the type of driveway material, the depth of the material, whether the material is reinforced and the overall makeup of the driveway's foundation or base. You can be fairly certain that anything over a few tons, or 10,000 pounds, will potentially crack a poorly installed residential driveway.
Preventing driveway cracks
Preventing cracks is a much better option than repairing them, for obvious reasons, but true prevention can only happen during the driveway's installation. The driveway's base is the biggest factor when it comes to excessive cracking, so choosing to hire a professional driveway contractor to install the driveway, versus laying the material yourself or getting a friend to do it, will help ensure the material has a stable subsurface.
If the installation is done correctly, the only preventive measures you need to take are the occasional sealing to keep out excess water and to avoid damaging the concrete through salt or heavy weights.
RELATED: Should You Sealcoat Your Driveway?
Editor's note: This is an updated version of an article originally posted on March 5, 2013.