Cracks and water leaks often occur in basement cement flooring. Over time, cement has a tendency to wear away and crumble, causing cracks and large chunks of broken concrete. The best way to fill a cement crack to stop water leaks from occurring and spreading through the cement is with polyurethane or epoxy filler. These are low-pressure injection fillers that form to the adhesive put inside the cracks, filling up the space and preventing leaks.
Enlarge very fine cracks with the chisel and mallet. Cracks that are large enough to fit the surface ports into will not need to be enlarged. Smaller, finer cracks need to be slightly enlarged for the base of the surface ports to slip into the crack. It will not be secure until you add the adhesive.
Place the surface ports inside the cracks. For wide cracks, it is best to use a few surface ports, and not just one. Place each port about 1 inch apart from another, and remove the caps.
Fill in the entire crack with epoxy adhesive. Push the adhesive down to the very bottom of the crack, using a trowel or a thin putty knife. Surround the tip of the surface port as well. At this point, the entire crack should be filled with epoxy adhesive except for the inside of the port. This will take between 20 and 45 minutes to cure and dry completely. Use the trowel to smooth the adhesive and make the repair flush with the existing cement.
Inject the polyurethane or epoxy material into the port’s mouth. Make sure the injection tip is all the way inside of the hole. Begin filling with the material, and wait for the compression spring to slowly force the injector tip out of the port hole. It should slightly spill over the opening of the port. Plug each port by placing the cap on it tightly before you move on to the next port. Let the material inside the ports cure for 48 hours.
Remove the ports. The filler inside the ports will have spread throughout the cement, preventing water from penetrating through again.
Remove the surface ports by hitting them sideways with a mallet or trowel. This will loosen them, and then you can pull them out.