A different method and substance are required for repairing thin cracks as opposed to bigger, thicker ones. Select a liquid concrete crack filler or thin caulk that can readily flow into the crack and fill it. When selecting the best concrete crack filler , it is important to consider the crack’s width. A stronger caulk or patching product may be required for cracks between 1/4 and 1/2 inches in width. In the case of larger cracks, a patching compound or fast-setting concrete may be your best alternative. If the crack is small enough, you could try filling it with regular concrete. Using a resurfacer towards the end can assist conceal the repair and provide the surface some strength.