Fiberglass Supply Depot 4 Lb. Density Expanding Pour Foam, 2 Part Polyurethane Closed Cell Liquid Foam for Boat and Dock Flotation, Soundproofing, Filling Voids, and Insulation (1 Gallon Kit)

Awesome stuff, I used it to fill holes used from animals going under my cement driveway and walkway. Fantastic results and hardens like a rock

Works well. Be quick and ready for it, it expands quickly and will come for you if you're not prepared to control it.

It worked perfectly to replace floatation foam in a boat

Works great , quick set up and easy to use

Being a more dense foam I was hoping for more expansion but it did the job. I used this to repair my pool steps from where improper install caused the dirt to wash out underneath them. This filled the void well.