ESSRBOND GS 500 is a polyurethane hydrophobic injection grout. It reacts in contact with water to form a closed-cell 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 not affected by water or dryness. It can also be used as a negative side application. It forms an excellent bond with the contact surfaces. It tends to penetrate deeply into hairline cracks.