How strong is strong enough? This is a commonly asked question by costumers that are new to jacking with polyfoam. The foam only needs to be as strong as the dirt, but they’re actually stronger than crystalline bedrock.
Today polyurethane lifting foams are used to level airport slabs supporting jumbo jets, equipment and building slabs supporting tremendous loads, and even railway sleepers that support the heaviest freight trains. So don’t let the word “foam” fool you. These resins cure to strengths beyond what is needed to support any structure.