Sealing and Patching an Asphalt Driveway
Brother Morris’ son Morris III helps to run our remodeling company along with Morris’ wife Carol. Recently they asked about the most cost effective surface for a driveway – for a bid they were making. They wanted to know if asphaltic concrete (asphalt) would be less expensive and as durable as concrete for a really large driveway. The answer took about ten minutes. Are you ready?
Asphalt (also known as blacktop) is definitely more flexible than concrete, but its surface is not as durable as concrete. Therefore, we feel the best use for asphalt is where the ground is expansive (soil that expands and contracts as its moisture content changes). Concrete is stronger, and has a more resilient surface, than asphalt but it cracks plenty when poured in place over expansive soil.
Large, heavy pieces of equipment are predominantly used to install asphalt. Therefore it is easier to install, and it’s more cost effective to install, when asphalt is laid in large open areas (parking lots, large driveways, roads, etc. On the other hand, concrete easily can be installed in small, enclosed places. Both asphalt and concrete are easily patched by hand.
Actually, asphalt is very similar in makeup to concrete. Both contain an aggregate (gravel or rock) mixed into a binder. With asphalt the binder is a crude tar-like petroleum product. In concrete the binder is Portland cement. The petroleum binder in asphalt softens considerably in warm weather increasing its exposure to damage. Don’t poke at asphalt on a hot day. You’ll end up with a hole. Because asphalt is porous water and freezing conditions can take their toll. That’s why it is important to know how to care for it. By the way, knowing how to properly care for asphalt may have some bearing on which one to go with…concrete or asphalt.
Maintaining asphalt can be done professionally, but it really is easy to do and makes a great do-it-yourself project for a weekend. There are four areas of maintenance:
- Small crack repairs
- Large crack repairs
- Pothole repairs
Although sealing doesn’t have to be done each time a crack or pothole is repaired, it is a good idea to combine all of the tasks into a single project.
Before beginning the process you must fire completely clean the entire area to be sealed. A garden hose and a bristle brush and a bucket of soapy water will be needed. Mix a cup of powdered laundry detergent in a gallon of hot water and spread it over the area to be cleaned. Make sure the surface has been wet down with the hose first. Use the bristle broom to scrub the surface clean. If you were us you would be using a pressure washer instead of a broom – less work. By the way, our formula works really well on preparing grease stains too.
Small cracks (up to about a half-inch wide) can be filled with asphalt sealer. If the crack is deeper than a quarter-inch it should be filled with sand first. For cracks over a half-inch mix fine sand with the sealer. Be prepared to go back – in both instances – to apply a second coat where the crack patch settled.
The most fun repair is fixing a pothole. This is one repair that can be done quickly and that will really change the overall appearance of the surface. Hey, if we were talking about a driveway in the front of the house, we’d be talking major improvements to the home’s appearance and it value!
For the longest lasting repair you should call a professional in who will make a “hot patch”. This is where the asphalt is super heated. When applied it “melt-bonds” with the existing asphalt. Hot asphalt also dries harder and is therefore a more durable repair. However, if the cost of a hot patch isn’t in your budget you can follow these easy steps:
- Dig the area of the pothole to a depth of approximately six-inches.
- Clean all loose material out of the hole.
- Use a tamping tool to compact the sub-surface.
- Add crushed rock to the hole and tamp it leaving at least four-inches to the top.
- Use cold asphalt in a bag to make the rest of the repair tamping in one-inch-thick layers.
- A final layer (about a half-inch thick) should be applied to the patch covered with a layer of sand. Use the wheel of a car driven back and forth over the area until the repair is smooth.
- Brush away excess.
With cracks and potholes repaired the final step is to seal the asphalt. This should be done every three to four years. Use emulsified asphalt or coal-tar sealer. All you have to do is pour it onto the surface and spread it out to an even finish using a rubber squeegee. Some manufacturers recommend a second coat, but you want to be careful here. Applying too much sealer can result in a slick, slippery surface.
Asphalt maintenance and repairs should be done when the temperature is above 60 degrees Fahrenheit. Repairs made in warm weather render materials that are more pliable and that set more rapidly insuring a better bond. And, good luck!