How Asphalt Paving Works: Why Sandy Springs Pavement Cracks First
Asphalt is only the top layer. Under a typical home driveway sits an asphalt layer 3 to 5 inches thick on a stone bed 4 to 8 inches deep, and the stone does most of the carrying. Once water softens that bed, tires make the asphalt flex, then crack, then break. Poor drainage, a thin base and weak compaction do the most harm.
The ground in Sandy Springs makes this worse. Soil surveys list Cecil, Pacolet and Appling soils here, with subsoil that runs 30 to 47 percent clay, and wet clay has little strength. A base built too thin over it sags in the wheel paths, and cracks follow.
Weather adds the last piece. Atlanta collects about 50 inches of rain a year with no real dry season, and around 36 nights a year fall to freezing or lower. Water sits in every open crack, freezes and widens it, and the next thaw sends more in. Good paving is mostly base, drainage and compaction below the surface. A cheap bid that skips the base tends to cost more within a few winters, once the first potholes open. The asphalt is what you see, yet the work underneath decides if the pavement still rides smooth a decade from now. Ask any bidder what goes below the surface, how deep the stone will be and how it will be packed.