How Asphalt Paving Works: Why Johns Creek Pavement Cracks First
What you see on a driveway is a skin. Underneath, a bed of crushed rock does the heavy lifting, with asphalt of three to five inches resting on rock four to eight inches deep. If water softens that bed, the skin bends under each tire and splits along the stress lines.
Local ground raises the odds. Soil surveys here list Madison, Cecil, Pacolet and Appling soils, many with a clay-rich subsoil of 30 to 47 percent clay, and several streets pitch at 10 to 25 percent. Wet clay has little strength, and slopes push runoff across driveways at speed. A base built without those facts in mind gives out early.
Climate adds to it. Rain totals about 50 inches a year without a dry season, and nearly 36 nights fall to freezing or lower. Moisture enters every opening, freezes and expands, and the crack grows a little with each cold snap. So a good job puts more care below the surface than on top. Owners who understand this tend to ask better questions of every bidder, and they spend less on repairs later.