Minor cracks in concrete flatwork (i.e., driveways and walkways) are expected and considered normal. The inherent characteristics of concrete make cracks impossible to prevent. This happens for a number of reasons, including:

• Concrete shrinks as it dries, causing shrinkage that shows up as cracks
• Temperature changes cause expansion and contraction, that shows up as cracks
• Moisture under concrete can cause it to lift or sink, which causes cracks

If you are considering sealing or repairing a concrete crack, you should consult a professional to make sure the treatment is done correctly.