Repairing horizontal cracks in concrete is the first step in any home repair project. Proper safety gear, such as safety glasses and gloves, should be worn at all times during the crack repair process. Here is a list of everything you'll need: safety glasses, safety gloves, a standard caulk gun, a chisel or grinder (for more advanced repairs), a standard or drilling hammer, a utility knife, and a stiff wire brush. Before starting the repair, make sure that the surface is free of contaminants. Use a chisel and hammer to widen the crack to at least a quarter inch. Clean any loose debris with a wire brush. This step is necessary to allow the sealant to seep into the crack and form a proper bond with the concrete. Next, cut the plastic nozzle of the Sikaflex crack flex cartridge at an angle that matches the size of the crack. Use the seal punch rod attached to your caulk gun to puncture the foil through the nozzle. Insert the cartridge into the caulk gun. Fit the nozzle into the crack and apply the sealant down the length of the crack, ensuring a sufficient bead that is level with the surface. There is no need for tooling as the sealant will gradually self-level. Sikaflex crack flex sealant is a one-component, flexible, self-leveling polyurethane sealant. It is textured to blend with your concrete surface and adds density to prevent the sealant from running into the crack, unlike temporary crack fillers. This sealant utilizes elastic technology, allowing it to be used in cracks up to one inch wide. Once cured, the product remains flexible and durable, allowing for proper crack movement.