PU Grouting
Injection Services
Polyurethane (PU) injection — the gold standard method for permanently halting active water leakage in concrete structures. Fast-reacting, expanding and waterproof. Applied by certified specialists across Sri Lanka for basements, tunnels, pools and infrastructure.
Polyurethane (PU) Injection —
How It Works
Polyurethane (PU) injection is a standard method for halting water leakage that utilizes the hydrophobic properties of polyurethane. This versatile technique is extensively employed to repair cracks in concrete and honeycombed concrete using a PU injection grouting machine.
When PU resin comes into contact with water, it undergoes a chemical reaction — expanding rapidly to fill and seal the crack, void or joint from which water is escaping. The resulting foam is permanently waterproof, flexible and tenaciously bonded to the surrounding concrete. Unlike rigid repair mortars, the flexible cured foam accommodates structural movement without re-cracking.
PU grouting can be applied even when water is actively flowing through the crack — making it the technique of choice for emergency water stop situations in basements, tunnels, retaining walls and below-ground structures. The resin injection is performed under controlled pressure using a specialist grouting pump, forcing the resin deep into the crack and ensuring complete filling across the full depth of the structural element.
What Happens When PU
Meets Water
PU resin is pumped under controlled pressure through injection packers installed along the crack
On contact with water in the crack, PU undergoes a rapid chemical reaction — generating CO₂ gas
The CO₂ causes the resin to foam and expand — filling every void, crack and pore in the surrounding concrete
The cured foam forms a flexible, permanently waterproof seal — stopping the leak completely and accommodating movement
Two Types of PU Resin —
Choosing the Right One
Ideal for Active Water
Leakage Situations
PU grouting is the most effective technique for stopping active water infiltration in concrete structures — particularly in below-ground environments where access to the exterior waterproofing layer is impossible without major excavation.
- Basement walls and floors — water actively entering through cracks, construction joints, pipe penetrations and honeycombed areas
- Underground car parks — leaking walls, floors and slab soffits with active water ingress
- Retaining walls — hydrostatic water pressure forcing water through cracks and joints
- Tunnels and culverts — active leakage through structural cracks and construction joints
- Swimming pools and water tanks — leaking joints, cracks and pipe penetrations
- Bridge piers and abutments — water entering through movement joints and cracks
- Honeycombed concrete — voids and porous patches where full compaction was not achieved
- Lift pits and pump rooms — below-ground water containment structures
Key Advantages of
PU Grouting Injection
The PU Grouting Injection
Process — Step by Step
PU Injection in Practice —
Government & Infrastructure
Hi-Tech Concrete Solutions has carried out PU grouting injection works across a wide range of government, commercial and infrastructure projects in Sri Lanka — from historic heritage buildings to modern hospital complexes and national infrastructure.
- Structural crack injection at the Colombo Municipal Council heritage building
- Below-ground leak stopping in basement and underground structures
- Water ingress repair at government hospital facilities
- Construction joint waterproofing for below-ground concrete structures
- Emergency water stop injection for active infrastructure leaks
When to Choose PU
vs Epoxy Injection
| Criteria | 💉 PU Grouting | 🔵 Epoxy Injection |
|---|---|---|
| Best for | Active water leaks | Dry structural cracks |
| Crack condition | Wet or actively leaking | Dry or damp |
| Cured flexibility | Flexible foam | Rigid bond |
| Structural restoration | No | Yes — full bond |
| Movement joints | ✓ Ideal | ✗ Not suitable |
| Minimum crack width | 0.3mm+ | 0.1mm+ |
Complete Range of
Injection Solutions
PU Grouting Injection FAQs
Is Your Structure Actively Leaking?
Our PU grouting specialists will assess your leak and stop it permanently — free site visit, no obligation.