Cracks in concrete patios and walkways can occur when the ground below shifts. Not only is the result unsightly, but it can lead to chip outs and crumbling concrete. It's important to repair such cracks before winter, when frozen water can get inside, expand, and make things worse. To fix the concrete, take a chisel to the crack and break away any loose debris. Clean the area, then apply a concrete repair mix, following the manufacturer's instructions.