An asphalt driveway needs regular maintenance to protect and preserve it. Cracks invariably develop and must be filled. The entire surface should be sealed every year or two.
Before you patch cracks or holes, it's important to remove loose gravel and bits of asphalt. Clear weeds and dirt with a wire brush or trowel, followed by a shop vacuum or leaf blower. To remove dust, hose down the area. Then let it dry.
You can fill wide cracks and potholes with blacktop patch, a prepared asphalt sold in 60-pound bags. Fill the prepared hole about halfway with blacktop patch and compact it before filling it the rest of the way. Mound the material slightly, then flatten it down hard with a tamper. (You can make your own tamper by fastening a scrap piece of plywood or particleboard to a 2-by-2.) Use a flat shovel to cut away excess so the patch will be level with the surrounding surface. Freshly filled spots should cure for about 90 days before they are sealed. You can patch in the spring and seal in late summer.
As an asphalt driveway ages, narrow cracks develop along the edges. To repair these, clean them with a wire brush and vacuum up the loose material. Then fill with an asphalt crack filler that pours from a bottle. This leaves a patch resembling tar strips on an old highway. You can subdue the effect by brooming a small amount of fine sand into the filler.
There are three types of sealer for a blacktop driveway. An asphalt-base sealer, the most expensive, should be used only on new asphalt or on a surface that has been previously sealed with the same material. Tar emulsion sealers are the least expensive and probably the most popular because they seal against gasoline, oil spills and drips. A third kind is a tar-base sealer, which contains fine black aggregate to give it extra body. This is used to fill large areas of cracking and to provide traction on steep drives. A 5-gallon can of sealer will cover about 350 square feet.
You can mix fine sand with standard tar-base sealer to give it body, but the surface will take on a salt-and-pepper appearance as the sealer wears.
The outside temperature should be about 60 degrees when you apply sealer. The driveway must also be prepared before application. Cut away grass that grows over the edges. Sweep the driveway clean, concentrating on dished areas where rainwater and dirt collect. Then hose down the driveway.
Look for water beads on the surface that indicate oil or gasoline. Remove softened material from these spots and replace it with blacktop patch. You can work around the patch when you apply sealer to give the spots time to cure. If there is no softening, use strong detergent or trisodium phosphate and hot water to scrub away oil or gas residue. Then rinse the area thoroughly.
If you use the more expensive asphalt sealer, make sure the pavement is dry before beginning the application. If you use tar-base sealer, keep the pavement damp. Spread all sealers as thinly as possible, using a squeegee and then a brush. Two thin coats are better than a single heavy one. You should be able to walk on the sealed area after 12 hours and drive on it after 48 hours.