Polyurethane injection is a concrete repair method used to seal leaking or active cracks by injecting flexible polyurethane (PU) resin to prevent water ingress.
Explanation
Polyurethane resin reacts with moisture and expands, forming a flexible foam or gel that fills cracks and voids within concrete. Unlike epoxy, polyurethane remains flexible after curing, allowing it to accommodate minor movement.
Polyurethane injection is typically used where:
- Cracks are actively leaking
- Water ingress must be stopped
- Structural bonding is not the primary objective
- Movement may still occur
It is widely used in basements, retaining walls, lift pits, tunnels, and underground structures across the UK where hydrostatic pressure is present.
Why It Matters
Water ingress accelerates reinforcement corrosion and structural deterioration. Polyurethane injection provides a targeted and cost-effective waterproofing solution without the need for extensive breakout.
Correct assessment is essential to determine whether polyurethane (flexible sealing) or epoxy (structural bonding) is the appropriate repair system.