PU injection, also polyurethane grouting or injection, is a water- proofing technique that uses expanding injected polyurethane to prevent water flowing through and voids or cracks typically in concrete.
Injection grouting is the method of filling the cracks, open joints, voids, or honeycombs, in concrete or masonry structural members. This is done under pressure with a grout material that cures in place to produce the desired results like strengthening a structure and preventing water ingress.