Blessed be the ties that bind. Therein is the key difference between concrete and asphalt: The binder.
Concrete and asphalt are both made with a mixture of aggregate. Concrete is bonded with a mixture of water and portland cement that creates a chemical reaction and hardens. Asphalt is bound with a black, sticky petroleum-based substance. This substance is behind terms like “blacktop” or “tarmac.”
Because of the key differences between the two products, concrete and asphalt contractors will offer different services to match the installation requirements.
Each industry has its own set of certifications and your contractor should be certified in the product being used. For concrete, it’s an American Concrete Industry (ACI) certification. For asphalt, it’s through the National Asphalt Pavement Association. Some contractors may be certified in both, or they have crews dedicated to each material.
Both concrete and asphalt require a smooth, compacted base that allows good drainage. Think of the surface as the roof of your home. If the foundation and walls are sagging and allowing water in, the roof is going to sag and fail. Your contractor should provide a good base for your product.
Water is a common enemy of driveways and parking lots. Once water gets into dips or pits in the material, the freeze-thaw cycle can break up both asphalt and concrete. That’s why it’s critical to have a well-drained base and adequate slopes to your surface to remove surface water and melting ice or snow.
Asphalt will be hot when it’s installed and cannot be placed in excessively cold temperatures. In fact, most asphalt companies in Michigan completely shut down in the coldest winter months, so the product is not even available during cold periods of the year (typically mid-November thru mid-April). With insulating blankets or other materials, the heat created by curing concrete allows it to be placed during all but the most extreme cold temperatures.
Concrete allows many more options for decorative colors and patterns. Because of asphalt’s dark binding materials, it’s much harder to use decorative colors or finishes. Some designs can be stamped into the finish, but because asphalt is more pliable, the longevity of custom designs isn’t strong.
Concrete contractors will have to install forms to contain the material as it’s poured and smoothed. This process adds time to the build, but it also gives clear edges which are often more durable than asphalt. Asphalt is known to crumble at the edges if it’s not bordered by a hard surface. That’s why most curbs and gutters are made of concrete. Even when a large parking area or a street is paved with asphalt, curb and gutter will be made of concrete to give a hard edge to protect the edges of asphalt.
Smoothing concrete can be accomplished with hand tools, usually mounted on long poles. Smoothing asphalt requires a heavy roller and it’s harder to achieve a smooth surface without divots or dips. In a massive concrete project, such as miles of roadway, a machine will be used to level the concrete, but when it comes to residential projects, usually hand tools will do the work.
Concrete will usually need to cure for about a week before it can handle heavy traffic. While asphalt can handle traffic almost immediately, immediate use can contribute to channels, dips, or divots. Your contractor can work with you to do the project in stages to accommodate use.
Another key difference between asphalt and concrete will be in maintenance. In the first year, concrete contractors recommend limited use of or avoiding de-icing products all together. Sealing concrete isn’t required but using a quality surface sealant every five years can prolong the life of your concrete and protect it from excessive cracking and flaking. With asphalt, sealants must be applied six months after installation and every three to five years afterwards.
Because concrete is so hard and durable, it doesn't “flex” with extremely high temperatures or with wear like asphalt will. Your contractor will saw, groove or score large sections of concrete to provide relief cracks as concrete ages and channel water off the surface. This is normal and a best practice.
Nothing beats concrete’s longevity! A concrete driveway or parking lot installed on a solid base with good drainage will last 30-40 years, nearly double the average life span of an asphalt product. While the initial installation cost may be higher and slightly longer for concrete, the easier maintenance, the decorative options, the longevity and the increased property value make concrete a more attractive choice for your driveway or parking areas.