STP ShaliGrout PU F
Single-component hydrophobic polyurethane injection grout that reacts with water to foam and seal active leaks, cracks and gushing joints in concrete structures.
What is it?
A single-component, hydrophobic polyurethane injection resin from STP that reacts on contact with water to form a semi-flexible, non-toxic foam. It carries a built-in accelerator, so no separate catalyst or second component is needed.
Where is it used?
Leaking basements, retaining walls, tunnels and shield-lining joints, sewer pipes, dam and bank seepage, and construction or expansion joints where water is actively flowing or oozing.
Why use it?
It stops heavy water ingress fast. On contact with water the resin expands more than 8 to 12 times its volume, driving foam into the finest cracks and pores to form a stable, elastic seal that will not degrade.
How is it applied?
Pumped through a single-component high-pressure injection pump into pre-drilled ports or directly into the leaking crack. The resin meets water in the substrate, foams, cures and locks off the flow path.
About STP ShaliGrout PU F
STP ShaliGrout PU F is a single-component polyurethane injection grout built for one job: stopping water that is already moving through a concrete structure. Unlike two-part injection systems that need careful ratio mixing on site, PU F ships ready to pump with an active accelerator already blended in. It stays inert in the drum but reacts the moment it meets water in the crack, so the material does the metering for you and there is far less that can go wrong in a wet, awkward injection position.
The chemistry is hydrophobic and water-triggered. When the resin contacts groundwater, seepage or a deliberately introduced water flush, it foams and expands rapidly, driving itself into hairline cracks, honeycombing and pores that a rigid resin could never reach. The cured product is a tough, semi-flexible, chemically stable foam that resists saline and mineral water and does not break down over time. Space Arc Engineering supplies ShaliGrout PU F across Delhi NCR and pan-India as an authorised STP distributor, and can advise on pump selection and injection sequencing for the specific leak you are chasing.
The technical insight
The performance comes from the water-reactive isocyanate chemistry combined with the built-in accelerator. As soon as the resin meets water, the reaction kicks off and generates carbon dioxide, which foams the material and forces expansion of more than 8 times at 2% water, over 10 times at 5%, and over 12 times at 10% water content. That controlled expansion is what lets the grout chase a live leak upstream into cracks too fine to inject mechanically. The reaction is fast but staged: at 27C and 55% RH the cream (start of foaming) begins in roughly 25 to 45 seconds, the mass rises over the next few minutes, and it becomes tack-free within about 210 to 750 seconds depending on how much water is present. More water means faster reaction and greater expansion, which is why applicators sometimes pre-wet a dry crack. Because the cure is hydrophobic rather than water-absorbing, the resulting foam does not shrink back when the structure later dries out, so the seal stays intact through wet and dry cycles.
Where it is used
- Stopping heavy, fast-flowing water ingress into basements, tanks and below-grade structures
- Sealing water oozing from ground, dam bodies and canal or river banks
- Arresting leaks from large and small-diameter sewer pipes
- Sealing leaking concrete cracks and expansion joints
- Stopping water penetration into tunnels through shield-lining joints
- Back-grouting behind structures to fill voids and gaps and restore stability
- Curtain and contact grouting against active hydrostatic pressure
- Emergency leak-sealing during construction before permanent waterproofing
Key advantages
- Reacts on contact with water and does not depend on ambient temperature to cure
- Single-component and self-metering, so no on-site mixing ratios to get wrong
- Expands more than 8 to 12 times in volume, reaching hairline cracks and pores rigid resins miss
- Short gel time gives a tough, resilient gel quickly so flow is arrested fast
- Forms a strong, elastic, chemically stable foam that is non-degradable for a lasting seal
- Works with saline and mineral water as well as fresh water
- Excellent adhesion to the surrounding concrete and substrate
- Surface-active, so it impregnates even the finest cracks during expansion
Limitations & considerations
- Strictly a water-stopping resin, not a structural or soil-stabilising material and it should not be used to reinforce or stabilise soil
- Needs an active water source to cure, so genuinely dry, static cracks may require pre-wetting
- Do not apply below 10C, as the resin can crystallise and reaction slows
- Requires a dedicated single-component high-pressure injection pump, which must be flushed clean immediately after use
- Once a bucket is opened it must be used up, as exposure to moisture and air starts consuming the material
- Injected resin must be kept from flowing into rivers or the natural environment, so containment planning is needed near watercourses
Selection & best practice
Condition the material to a workable temperature for at least 12 hours before use and never inject below 10C. Roll or shake the drum, then mix briefly with a clean, dry drill and paddle for around 15 seconds to homogenise before loading the pump. Inject with a single-component high-pressure pump through packers set along the leak path; where a crack is dry, introduce a controlled water flush so the resin has moisture to react against. Because more water means faster, larger expansion, stage your injection to chase the flow rather than flooding one port. Keep containers tightly sealed between uses, flush the pump thoroughly with STP-recommended cleaning agent immediately after injecting, and remember that once cured the foam can only be removed mechanically. Use gloves, mask and eye protection throughout.
Specifications
| Chemistry | Single-component hydrophobic polyurethane with active accelerator |
| Appearance | Brown liquid |
| Density | 1.18 ± 0.05 g/cc |
| Viscosity | 250 – 500 mPa.s |
| Flash point | >202 °C |
| Cream time (start of foaming) | 25 – 45 sec (at 2 – 10% water, 27°C) |
| Tack-free time | 210 – 750 sec (depending on water content) |
| Volume expansion | >8x at 2% water, >10x at 5%, >12x at 10% |
| Pack size | 20 kg bucket |
| Shelf life | 1 year, unopened, stored 10°C – 38°C, out of sunlight |
Industry use cases
Metro & Tunnelling
Sealing water ingress at shield-lining segment joints and construction joints in bored and cut-and-cover tunnels during and after excavation.
Water Retaining Structures
Stopping active seepage in basement rafts, retaining walls, sumps and tanks where two-part injection is impractical in wet conditions.
Sewerage & Utilities
Arresting infiltration leaks in large and small-diameter sewer and utility pipelines and their surrounding concrete.
Dams & Hydraulic Works
Curtain and contact grouting to stop water oozing from dam bodies, canal linings and river or canal banks.
Building Repair
Emergency leak-sealing of cracked or honeycombed concrete and expansion joints in occupied buildings before a full waterproofing overlay.
Frequently asked questions
Is ShaliGrout PU F single or two component?
How much does it expand?
Can I use it to fill a dry crack?
What pump do I need?
Will it work in cold weather?
What pack size and shelf life does it come in?
How we position STP ShaliGrout PU F
ShaliGrout PU F is the go-to STP resin when water is actively flowing and you need it stopped now. Where the crack is stable and you want an elastic, controlled cure rather than aggressive foaming, STP’s two-component injection resins are the natural next step: ShaliGrout PU 2K and PU 2K FS are low-viscosity, solvent and phthalate-free systems for elastic sealing of concrete cracks, and PU 2K 20 is a hydrophobic two-part option for larger water flows. Pair the injection work with an STP surface waterproofing membrane or crystalline system for the permanent barrier once the leak is arrested. Space Arc also carries comparable water-stop and crack-injection lines from Fosroc, Sika and Dr. Fixit, and our team can match the right resin, packer and pump to your specific leak. Note that for rigid structural crack bonding, an epoxy injection resin rather than a water-reactive PU is the correct choice.
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Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.