Abstract: A closed cell, HFC-245fa blown rigid polyurethane foam system designed for lifting concrete composite slabs back to their original position in either wet or dry site conditions. The blown rigid polyurethane foam includes an isocyanate (A) component and a polyol (B) component. The isocyanate and polyol are fed to a metering system and separately pumped to a two-component mix head. An exit nozzle of the mix head is extended into an injection hole formed in a slab and injected into a void beneath the slab to be lifted causing a reaction. The reaction creates a closed-cell foam that lifts and supports the concrete slab.