Resfoam HL 35
Resfoam HL 35 is a flexible, hydrophilic polyurethane foam or gel resin. It is a single-component, water-activated system that absorbs water to form a flexible foam or gel, making it ideal for sealing cracks and joints that are subject to movement and continuous moisture.
Applications & Uses
- Sealing cracks and joints in concrete structures subject to movement - Curtain grouting behind tunnel linings - Sealing manholes and utility vaults - Stopping leaks in construction joints
Features & Benefits
- Single-component and easy to use - Hydrophilic nature ensures excellent bond to wet surfaces - Forms a flexible foam that accommodates movement - Can absorb up to 5-10 times its weight in water - Good chemical resistance to sewage and ground water
Technical Specifications
- Chemical Base
- Hydrophilic polyurethane
- Viscosity
- 350 - 450 mPa·s
- Density
- 1.05 g/cm³
- Expansion
- Up to 500%
- Elongation
- > 100%
Frequently Asked Questions
How a Product Like This Gets Specified
Choosing a material is the last step, not the first. On every job the order is the same: establish the defect mechanism, decide which part of BS EN 1504 governs the remedy, then pick a product whose declared performance class satisfies it. Reaching for a product first is how repairs fail a second time.
- Diagnosis. Hammer survey for delamination, cover meter readings, carbonation depth to BS EN 14630, chloride sampling where salt is in play, and water path tracing where something is leaking.
- Standard. BS EN 1504-2 for surface protection and coatings, -3 for repair mortars (class R3 or R4 where the repair carries load), -5 for injection products, -7 for reinforcement protection, and BS 8102:2022 where the structure is below ground.
- Substrate preparation. BS EN 1504-10 governs this, and it decides more repairs than the product does — a sound, correctly profiled, correctly saturated substrate, with the micro-cracked layer left by percussive breakout removed.
- Conditions on the day. Substrate temperature, substrate moisture content and dew point all have to be inside the manufacturer's window before anything is mixed. This is why winter work takes longer, not why it costs more.
- Verification. Pull-off adhesion testing to BS EN 1542 on completed repairs, so the bond is a measured number rather than an assumption.
We are happy to say when a cheaper product does the same job, and when the product named in a specification is the wrong one for the defect in front of us. Background reading: our concrete repair cost guide, the concrete spalling repair guide, and the BS 8102:2022 compliance checklist for below-ground work.
Reviewed by Jerry Blears, Director (LinkedIn), MPS Concrete Solutions. Last reviewed October 2026.
Send photographs of the defect and we will tell you whether Resfoam HL 35 is the right answer — including when it is not. We can also send the technical datasheet and safety data sheet, or book a free site survey with a written diagnosis and a fixed, itemised quotation.
