Undersealing is the injection of material, today polyurethane foam, into voids beneath pavement or slabs to restore uniform support and eliminate movement without raising the surface.
In depth
Undersealing is widely used on highways, tollways, and industrial floors where slabs have lost contact with the soil but are still at the correct elevation. Filling the gap prevents the slab from deflecting under traffic or loads, which is what leads to cracking, pumping, and joint failure. The foam is engineered to travel far and fill thoroughly so support is continuous.
It is closely related to void filling and joint stabilization, and is often specified by transportation departments as a maintenance step to extend pavement life.
How Acme applies it. Acme’s RR-401 commercial foam exceeds typical specifications for DOT undersealing projects, and RR-501 is formulated to spread far for undersealing and stabilizing joints on rocking slabs.
Related terms: Void Filling, Concrete Stabilization, Rocking Slab, Compressive Strength
Frequently asked questions
Does undersealing lift the slab?
No. Its purpose is to fill voids and restore support while keeping the slab at its existing elevation. Foams with slower reaction times are used so the material spreads instead of lifting.
Why do highways need undersealing?
When voids form under pavement, slabs flex under traffic and begin to crack and fail at the joints. Undersealing restores continuous support and extends the life of the pavement.