Prime Flex 920 is a single-component polyurethane injection resin used to seal gushing leaks and wide gaps in concrete where the structure is not subject to movement. It is a hydrophobic, low viscosity polyurethane that reacts with water and expands to form a closed-cell, watertight, rigid foam. Its low viscosity also makes it suitable for permeation grouting of loose soils to consolidate them and increase load-bearing capacity. For high strength or large void filling, Prime Flex 985 is recommended. This material requires a catalyst (Prime Kat or Kick Fast Kat) to adjust the reaction time.