Wide concrete cracks should be filled and sealed with a concrete patching material. Concrete caulk or liquid filler can be used to heal little gaps less than 1/4 inch wide. Typically, patching chemicals are combined with water and applied with a trowel. The mixture is then smoothed out with the edge of a tool such as a float or rubber mallet. Cracks that are wider than 1/4 inch should be repaired with a concrete patch that is 2 by 4 inches or larger. Such patches should be smooth on one side only; otherwise, they will not adhere properly to the wet concrete. Smaller concrete cracks may be closed up with the help of a concrete repair kit. These kits usually include items such as plastic or metal strips and mesh, buttons, beads, and other items commonly found in a home improvement store. They are used to patch small holes or tears in concrete caused by broken glass or nails. The strips and mesh are placed over the crack and held in place by pressing them gently into the wet concrete. Then more water is added and the material is pressed into the wet cement to fill in the crack. Concrete repairs should be done before the concrete has time to dry out so that the materials will remain flexible while still sealing the crack effectively.