If you've been limping along for years with a cracked, crumbling driveway, asphalt may be just the material you need for a flexible, cost-effective—and quick—new driveway. Note that this is not the same as asphalt driveway sealant, which is a coating used to refresh existing asphalt. Asphalt is one of the most popular driveway materials, along with concrete, and it offers reasonable durability at a middle-of-the road price.
What Is Asphalt Paving?
Asphalt driveway material is similar to what you see road crews laying on roads. Also called hot mix or hot mix asphalt, it is an aggregate of stone and sand, along with a slurry of asphalt, a tar-like material made from petroleum. The asphalt is heated to over 300 F to liquefy it. Asphalt contractors have to work with it fast before the mix solidifies.
Hot mix is not driveway sealant or crack sealant. These are merely surface treatments for repairing or renewing worn asphalt driveways. Some asphalt patching materials are similar to hot mix but are not heated prior to application and cure differently from hot mix. While homeowners can repair or reseal an asphalt driveway, installing new asphalt paving is not a do-it-yourself job.
Asphalt vs. Concrete Driveways
There are several factors that make asphalt a desirable option for a new driveway.
- Flexible: Asphalt is more flexible than concrete and thus is less prone to cracking.
- Less expensive: Asphalt paving is typically cheaper than concrete.
- Hardier in winter conditions: It is less prone to damage by rock salt and ice melt.
- Faster-setting: Asphalt sets faster than concrete because it hardens by cooling rather than curing.
- DIY fixes: When you eventually need to resurface your asphalt, you can do it yourself with driveway sealant. Concrete cannot be resurfaced by the do-it-yourselfer.
On the flip side, asphalt has some drawbacks when compared to concrete:
- Lower resale value: Compared to asphalt, concrete typically has a higher perceived value by home buyers.
- Uneven edges: Unless you install concrete edging to hold in the hot mix, the edges of an asphalt driveway tend to be less than perfect.
- Plants: While not a common occurrence, some plants can force up through asphalt. Bamboo is one such plant.
Options for the Asphalt Paving Base
An asphalt driveway is only as good as its base. Asphalt installed on an unstable base can develop problems quickly. There are three main options for base installation:
- Install paving over existing driveway: If your existing driveway is in good condition and is not severely cracked or crumbling, hot mix asphalt can be laid right on top of your driveway. One consideration is height: Make sure that fences, garage floors, and other structures will not be affected by the higher level of the new surface.
- Remove old driveway, pave on soil: The existing driveway is completely removed (or you may not even have an existing driveway) and 4 to 6 inches of hot mix paving is laid directly on the soil.
- Remove old driveway, pave on aggregate base: This is the preferred method. An aggregate stone base partially replaces some of the hot mix asphalt. Typically 6 to 8 inches of aggregate go under 3 inches of asphalt.
Asphalt Paving Installation
Once the base preparation is complete, an average driveway may begin looking like a finished product is as little as 40 minutes. However, more time will be needed to compact the asphalt. After this, the asphalt needs to harden. Under most conditions, you will be able to drive on the driveway within two to three days, but it can take 30 days or more for asphalt to fully cure. During that time, you can use the driveway normal, but you should be careful to avoid scuffing the surface with car tires (by turning too sharply) and other common causes of damage.
The Best Time to Install Asphalt
Hot mix asphalt paving is dependent on warmer temperatures for workable conditions. This means that spring and summer are the best seasons for installing an asphalt driveway.
The colder the air temperature, the less time asphalt paving crews have to work with the asphalt. Crews need time to smooth the asphalt across your driveway. If they do not have enough time, your driveway may be bumpy, uneven, or irregular, or the project may not even get finished. While it depends on where you live, winter is not a good time to install driveway asphalt.
The thickness of the paving is another factor. The more asphalt you are dealing with, the more leeway you have. For instance, at 40 F, crews have only 16 minutes to work with 1 1/2-inch thick asphalt. But as the depth of asphalt grows to 3 inches, so too does the workability time: 46 minutes. Generally, for thin applications of asphalt (around 1 1/2 inches) you will want to wait until the temperatures are at 70 F or better. Between 50 and 60 F, you will need to consult with your contractor. The hot-mix is still workable during this timeframe, but time is limited.