Fibgrout PU 1K is a hydrophobic grout based on polyurethane. Upon contact with water, Fibgrout PU 1K reacts to closed cell rubber-like foam while expanding its volume up to 27 times. The cured material is of a constant volume. Since water is not a component of the foam structure, the cured material is essentially not affected by water or dryness. The reacted material does not shrink or swell. Depending on the pressure of injection, Fibgrout PU 1K reacts to a very dense material or foam.