CHEMRIGID is a moisture activated polyurethane chemical grout sealant containing prepolymer isocyanates (MDI). CHEMRIGID is a single component, solvent free, non toxic product which reacts with water to create a hydrophobic, rigid and chemically resistant foam. Once the chemical reaction is complete, the foam becomes a completely inert material. This polyurethane reacts with water rapidly and can expand up to 30 times its volume to stop large volume and high pressure water infiltrations. It can be used to fill large voids either in or behind concrete or masonry structures.