If you have a concrete driveway, patio, walkway or any other concrete structure with minor surface cracks, one of the best ways to repair these cracks is to fill them in with concrete repair caulk. Although this will repair the crack, the caulk will not match the color of the concrete and will be visible when cured. However, there is a little trick that can be done to completely hide the repair once the crack has been filled.
Clean the crack in the concrete using a soft wire or nylon brush. Brush out all the loose concrete, dirt and dust inside of the crack.
Snip the opening of the concrete caulk tube at a 30-degree angle and try to keep the opening in the tube the same width as your crack. Concrete caulk is available at any hardware store. Fill the crack with caulk until it is flush with the surface. Take an old spoon, and smooth the caulk bead. Wipe the spoon clean as needed with a rag and mineral spirits.
Sweep the concrete around the crack with a broom to collect dust. Sweep this dust onto the caulk that is in the crack. The concrete dust will cover the caulk and make the repair look exactly like concrete. Once dry, you won't be able to see the crack.