STP ShaliGrout PU 2K FS
A low-viscosity, two-component polyurethane injection grout that stops water in live cracks and cures to a permanent, flexible seal.
What is it?
A solvent- and phthalate-free, two-component low-viscosity polyurethane injection resin from STP that reacts with water to form an expanding flexible foam, and cures to an elastic resin where no water is present.
Where is it used?
Leaking cracks and construction joints in concrete and masonry, water-retaining structures, sewage treatment plants and below-grade substructures.
Why use it?
It does two jobs with one material: an immediate foam plug stops the active leak, and a follow-up injection with the same pump and packer converts it into a durable, elastic, permanent seal.
How is it applied?
Premixed 100:60 by weight and pressure-injected through packers at up to 200 bar, with a second pass through the same packers within 20-25 minutes to build the elastic seal.
About STP ShaliGrout PU 2K FS
STP ShaliGrout PU 2K FS is a two-component, low-viscosity polyurethane injection system built for one of the most stubborn problems on a construction site: water moving through a live crack. Because it is solvent-free and phthalate-free, it is comfortable to use in confined below-grade spaces like basements, lift pits and sewage works, and it is rated safe in contact with potable water. The chemistry is deliberately dual-natured. When the resin meets water inside a crack it reacts quickly and expands into a flexible foam that physically blocks the flow. Where there is no water, the same material cures instead to a tough elastic resin. That combination is what lets a single product both arrest an emergency leak and, on a second pass, leave behind a long-term seal.
What makes it practical for Indian sites is how forgiving the working window is. The long pot life (35-45 minutes before water contact) means it can be mixed and pumped as a single-component premix through an ordinary one-part injection machine, so no expensive two-line metering rig is needed. The mixed viscosity of just 150-200 mPa.s lets it travel deep into hairline cracks from 0.1 mm upwards, and it bonds to dry, damp and actively wet substrates alike. It handles the temperature swing from a cold basement to a summer terrace, working anywhere from 5°C to 45°C, and the cured resin is impermeable, so it holds up under high hydrostatic head rather than simply masking the symptom.
The technical insight
The clever part is that reaction speed is governed by water, not by a hardener. Mixed and kept dry, the resin has a leisurely 35-45 minute pot life and an 60-80 minute gel time, so it stays liquid inside the packer long enough to be re-injected. But the instant it contacts water in the crack, the isocyanate reacts with that water, releasing gas that drives more than 1500% free-foam expansion, with a cream time of just 50-70 seconds and a gel time of 200-300 seconds. That is why the first injection can chase and plug gushing water in minutes. Once the leak is choked and the surrounding concrete is no longer feeding water, a second injection of the same premix within 20-25 minutes finds dry conditions and cures instead to an elastic resin at roughly 85-95% elongation at break. The result is a two-stage seal from one drum: a foam barrier that stops the flow, then a flexible resin core that stays watertight while accommodating slight crack movement and resisting high back-pressure.
Where it is used
- Emergency sealing of gushing or seeping cracks in basements, tunnels and lift pits
- Permanent elastic sealing of leaking construction and cold joints
- Waterproofing of water-retaining structures and reservoirs
- Crack and joint sealing in sewage and effluent treatment plants
- Curtain and crack injection in below-grade substructure concrete
- Sealing fine cracks in masonry walls and retaining structures
- Re-injection of previously grouted cracks to convert a foam plug into a permanent seal
- Injection where potable-water contact requires a non-toxic grout
Key advantages
- Dual action from one material: stops the leak as foam, then seals permanently as elastic resin
- Low 150-200 mPa.s viscosity penetrates fine cracks and voids down to 0.1 mm
- Long 35-45 minute pot life allows pumping through a simple single-component injection machine
- Bonds reliably to dry, moist and actively wet concrete or masonry
- Cures to an elastic resin (85-95% elongation) that tolerates minor ongoing movement
- Impermeable cured resin withstands high hydrostatic pressure
- Solvent- and phthalate-free, low VOC (<50 g/L) and safe for potable-water contact
- Works across a wide 5-45°C application range for hot and cold sites
Limitations & considerations
- This is an injection resin for cracks and joints, not a coating or a general void-filling grout
- Requires an injection pump capable of up to 200 bar plus packers and trained applicators
- Reaction speed depends on temperature and moisture, so on-site trials are advised before large works
- Once a pack is opened it must be used immediately, and any part-pack purged with nitrogen to avoid moisture pickup
- Modest 6-month shelf life and a relatively narrow 5-35°C storage band
- Not a structural crack-bonding grout: where load-transfer and monolithic strength are the goal, a rigid epoxy injection resin is more appropriate
Selection & best practice
Drill and fix packers along the crack, then flush the crack with clean water to gauge the flow and pre-wet the substrate. Pour Part A into a clean, dry plastic bucket, add Part B at the 100:60 ratio by weight, and blend for about half a minute with a slow-speed stirrer until homogeneous, keeping the reservoir covered so ambient moisture cannot start the reaction early. Inject sequentially from the lowest packer upward on a vertical crack, driving the resin in at high pressure so it reaches the finest fissures. Because the premix stays liquid in the packer, return and re-inject the same packers within 20-25 minutes; when clear resin (rather than foam) refuses from the crack face, that length is fully sealed. Open drums only when the material is at or slightly above the working-area temperature to prevent condensation, wear gloves, mask and eye protection throughout, and clean tools before the resin sets, since cured resin can only be removed mechanically.
Specifications
| Composition | Two-component, solvent- and phthalate-free polyurethane injection resin |
| Mixing ratio | 100:60 by weight (2:1 by volume) |
| Mixed viscosity | 150-200 mPa.s at 25°C |
| Pot life (no water contact) | 35-45 minutes |
| Gel time with water contact | 200-300 seconds (cream time 50-70 seconds) |
| Free foam expansion | >1500% |
| Elongation at break | 85-95% |
| Minimum crack width / application temp | 0.1 mm / 5-45°C |
| Packing | 8 kg pack (5 kg Part A + 3 kg Part B); 6 months shelf life at 5-35°C |
Industry use cases
Basements & Below-Grade
Stops active seepage and gushing leaks through cracks and construction joints in raft slabs, retaining walls and lift pits, then leaves a flexible permanent seal.
Water & Sewage Infrastructure
Seals leaking cracks in reservoirs, water tanks and effluent treatment structures, with non-toxic chemistry suitable for potable-water contact.
Tunnels & Metro Works
Rapid foam plugging of water ingress in segmental linings and construction joints under high hydrostatic pressure in confined, poorly ventilated spaces.
Repair & Rehabilitation
Re-injection of old, previously grouted or newly cracked concrete to convert an emergency foam plug into a durable elastic seal using the same pump and packers.
Frequently asked questions
Does ShaliGrout PU 2K FS stop water immediately or only seal cracks later?
Can it be pumped with a single-component injection machine?
What crack widths and moisture conditions can it handle?
Is it safe for water tanks and potable-water structures?
How is it packed and how long does it last?
When should I choose an epoxy injection grout instead?
How we position STP ShaliGrout PU 2K FS
Within the STP ShaliGrout range this is the go-to for live, leaking cracks where a flexible seal is needed; for wider structural gaps and non-shrink anchoring you would instead reach for STP’s cementitious grouts. Across our other brands, the direct alternative is Fosroc’s Nitofill PU family of polyurethane injection resins, while for rigid structural crack bonding on dry concrete an epoxy injection resin like Fosroc Nitofill LV is the right call. For the surface-side of the same waterproofing job, pair it with a coating such as Fosroc Brushbond or an STP ShaliSeal membrane once the cracks are sealed. Space Arc supplies and applies the full STP and Fosroc ranges across Delhi NCR and Pan-India, so we can specify the correct resin for the leak in front of you rather than forcing one product to fit.
Fosroc Nitofill PU25 LV — Choose the Fosroc PU25 LV when a project is already specified on the Fosroc system or the specifier wants a two-component low-viscosity elastic PU injection resin from the same manufacturer as the surrounding repair scheme.
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