Shrinkage Cracks
As concrete cures it loses moisture and shrinks slightly. Fine hairline cracks that appear within the first weeks are usually shrinkage cracks and are largely cosmetic when they are narrow and shallow.
Control-Joint Behavior
Control joints are cut or tooled into the slab so that inevitable shrinkage cracks form in a straight, controlled line. Cracks along joints are working as intended. Cracks that ignore the joints usually indicate spacing or timing issues in the original pour.
Settlement
If the base under the driveway compresses or shifts, the slab loses support and cracks. Common causes include poor initial compaction, erosion, plumbing leaks and loose fill.
Weather Cycles
Repeated heating, cooling and moisture changes expand and contract concrete over time. Slabs without properly spaced expansion joints can crack at the weakest point.
Tree Roots and Loads
Roots growing under the slab can push it upward and crack it. Regularly parking vehicles heavier than a residential driveway was designed for can also produce cracks.
When to Take Action
Cracks that grow, widen or show vertical displacement warrant a professional evaluation. Request an evaluation or read about repair vs. replacement.