Asphalt sealer stops cracks in their tracks

Q: Several years ago, maybe three, I had my driveway and parking area covered with new blacktop (asphalt). Because I live on a hillside and the driveway is steep, the contractor compacted it with hand machines, not a “steamroller” as I would have preferred. The parking area is slightly inclined toward the driveway. Now, cracks have appeared – some long, some short – in both areas, the driveway and parking. How do I treat this problem to contain it? Is regular maintenance required on blacktop?

A: The cracks that appeared in your driveway over time are from the earth movement. Since you live in the Oakland (Calif.) Hills, an area where most of the soil is clay and there is quite a bit of earth movement, you can’t stop the cracks from occurring. So, maintenance is the answer. Establishing a regular maintenance program for sealing the cracks will prolong the life of your driveway and save you from a big replacement bill in the future.

The culprit taking advantage of cracks in your asphalt is – water. Normally, asphalt prevents water from penetrating to the underlying earth. That’s why it makes good roadways. If cracks develop, the seal is broken and water can penetrate.

In colder climates where the ground freezes, water penetrates, freezes and thaws, destroying the flatness of the road. This is called “frost heave.” A similar phenomenon occurs in soil that drains poorly, like clay. Water penetrates during the wet months, and the clay absorbs the water and expands, then dries out during the dry months, leaving larger cracks or uneven pavement.

So what to do?

Take a cue from highway departments in colder climates. In Boise, Idaho, where Kevin lives, the highway district has a regular rotation of sealing the roadways during the summer months. Although it’s a royal pain in the you-know-where to navigate around these projects, it would be a bigger pain, not to mention lots of tax dollars out of pocket, to rebuild the roads.

We recommend you establish a regular maintenance schedule to keep your cracks at bay. Here’s how:

There are a number of asphalt sealers on the market. Blackjack is one we’ve used. Essentially, these products are thin, liquidlike emulsions, which, when applied, seep into the cracks, dry and seal the surface. For larger cracks, you may have to apply a thicker sealer made for that purpose.

To investigate these products, check out your local home center, or give a call to a paving and grading contractor. The contractor may want to give you a bid. If so, that’s OK. Depending on the size of the job, it may be best done by the pros.

If you decide to do it yourself, make sure you clean the surface with, yes – water. Allow it to dry and then apply the sealer. A throwaway paint roller with a thick nap or an old broom will allow you to work the sealer into the nooks, cracks and crannies in your driveway. We would most likely approach a project like this toward late summer when the water content of the subsoil is lowest.

Bill and Kevin Burnett will attempt to answer your questions, although the volume of e-mail sometimes makes this impossible. Contact them at sweat-equity@comcast.net.