STP ShaliGrout PU 2K
A two-component, solvent-free polyurethane injection resin from STP that cures to a tough, elastic seal, engineered for cracks that keep moving.
What is it?
A two-component, low-viscosity, solvent-free and phthalate-free polyurethane injection resin from STP Limited that reacts to a tough, flexible rubber-like mass.
Where is it used?
Live or moving cracks in concrete structures, tunnel linings, water-retaining walls, basements, foundations and other elements where slight movement is expected.
Why use it?
Unlike a rigid epoxy, its elastic cure accommodates crack movement without cracking or debonding, so the seal survives thermal and structural cycling.
How is it applied?
Metered, mixed and pressure-injected through packers set into pre-drilled ports along the crack line by trained applicators.
About STP ShaliGrout PU 2K
ShaliGrout PU 2K is STP Limited’s answer to a problem that defeats ordinary crack repair: cracks that refuse to stay still. It is a two-component, low-viscosity polyurethane injection resin that is both solvent-free and phthalate-free. When the two parts are combined in the correct ratio, the chemistry drives a controlled reaction that sets to a tough yet flexible resin. That flexibility is the whole point. Rigid injection resins are excellent where a crack is dead and structurally stable, but on any element that flexes with load, temperature or settlement, a brittle repair simply re-cracks. ShaliGrout PU 2K is formulated to move with the substrate instead of fighting it.
For an engineer or applicator, the two properties that matter most are low viscosity and elastic cure. Low viscosity lets the resin travel deep into fine and hairline cracks under injection pressure, reaching the full depth of the fissure rather than bridging only the surface. The elastic cure then locks in a waterproof seal that behaves more like a rubber gasket than a hard plug. Because the formulation carries no solvents or phthalates, there is no shrinkage from solvent flash-off and it is a cleaner choice for enclosed spaces such as tunnels, tanks and basements. Space Arc Engineering supplies ShaliGrout PU 2K across Delhi NCR and pan-India, and as an applicator we can pair the material with the right packers, pump and injection methodology for the crack in front of you.
The technical insight
The reason ShaliGrout PU 2K works where others fail comes down to how a two-part polyurethane cures compared with an epoxy or a foaming grout. When the base and hardener meet, the isocyanate and polyol react to build a cross-linked polymer that is deliberately kept elastic rather than glassy. The result is a resin with real elongation capacity: it can stretch and recover as the crack opens and closes through daily thermal cycles or under live load, without the internal bond line failing. A rigid resin, by contrast, has almost no strain tolerance, so the first movement cycle after cure concentrates stress at the resin-to-concrete interface and the repair reopens. The second half of the mechanism is penetration. Injection sealing only succeeds if the resin actually fills the crack to its root, and low viscosity is what allows that under the modest pressures a hand or electric injection pump can generate. Thin resin wicks into capillary-scale fissures, displaces air and any standing water, and cures monolithically from face to core. Being solvent-free means the cured volume is essentially the injected volume, so there is no post-cure shrinkage voiding that a solvent-carried system would leave behind.
Where it is used
- Elastic sealing of live or dynamic cracks in structural concrete
- Injection of fine and hairline cracks in water-retaining walls and tanks
- Crack and movement-related injection in tunnel linings and segmental joints
- Sealing cracks in basements, retaining walls and below-grade structures subject to slight movement
- Foundation and raft crack injection where future settlement or flex is anticipated
- Rehabilitation of cracked bridge decks, piers and abutments exposed to traffic-induced vibration
- Restoring water-tightness to cracked concrete in STPs, WTPs and water-handling structures
- Sealing shrinkage and thermal cracks in slabs and walls that continue to breathe
Key advantages
- Elastic cure accommodates ongoing crack movement, so the seal does not re-crack like a rigid resin
- Low viscosity penetrates deep into fine and hairline cracks under injection pressure
- Solvent-free and phthalate-free, giving negligible shrinkage and safer use in enclosed spaces
- Two-component metered system delivers a consistent, controlled reaction on site
- Cures to a tough, waterproof rubber-like mass that resists hydrostatic pressure
- Bonds to the crack walls to restore continuity and block water ingress
- Suited to dynamic structures such as tunnels, tanks and bridges that a brittle repair cannot serve
- Backed by Space Arc as authorised distributor and applicator with pan-India supply and site support
Limitations & considerations
- Not intended for structural strength restoration or force transfer; for load-bearing crack bonding a rigid epoxy is the correct choice
- Requires pressure-injection equipment, packers and trained applicators, so it is not a brush- or trowel-applied product
- Being a reactive two-part system, mixed material has a limited working time and must be injected promptly
- Wider structural cracks or large voids are better treated with a dedicated flexible or foaming grout matched to the flow
- Correct crack preparation, port spacing and injection sequence are essential; poor technique leaves voids
- For active gushing water leaks, a water-reactive foaming PU is often the better first-line stop before elastic sealing
Selection & best practice
Start by mapping the crack and confirming it is a candidate for elastic injection rather than rigid bonding or foam stopping. Clean the crack face of dust, laitance and loose material. Drill injection ports at an angle across the crack line at spacing suited to the element thickness and crack width, and fit mechanical packers. Surface-seal the visible crack between ports so resin builds pressure inside rather than bleeding out. Mix the two components strictly in the specified ratio, using only what can be injected within the working time, and inject with a suitable pump from the lowest port upward, moving to the next port once resin shows. Keep pressure controlled so the resin penetrates without fracturing sound concrete. After cure, remove packers and make good the surface. For active water, consider stopping the flow first with a water-reactive foaming grout, then follow with ShaliGrout PU 2K for the permanent elastic seal. Always follow the current STP technical data sheet for ratio, temperature and handling, and involve Space Arc’s applicators where crack behaviour is uncertain.
Specifications
| Brand | STP Limited |
| Product type | Polyurethane injection resin grout for crack sealing |
| Composition | Two-component polyurethane (base + hardener) |
| Viscosity | Low viscosity for fine-crack penetration |
| Formulation | Solvent-free and phthalate-free |
| Cured character | Tough, flexible, rubber-like elastic resin |
| Function | Elastic waterproof sealing of live and hairline cracks |
| Application method | Pressure injection via packers |
| Pack sizes | 5.5 kg and 8 kg (confirm current packing with Space Arc) |
Industry use cases
Tunnels & Metro
Sealing movement-related and hairline cracks in tunnel linings and segment joints where vibration and slight movement rule out a brittle repair.
Water & Wastewater
Restoring water-tightness to cracked walls of tanks, STPs and WTPs with a flexible seal that tolerates fill-and-empty cycling.
Basements & Below-Grade
Injecting cracks in retaining walls and basement slabs to stop seepage while accommodating minor structural movement.
Bridges & Infrastructure
Elastic crack sealing on decks, piers and abutments subject to traffic-induced vibration and thermal cycling.
Industrial & Commercial
Sealing shrinkage and thermal cracks in slabs and walls of plants and buildings that continue to breathe over time.
Frequently asked questions
Is ShaliGrout PU 2K rigid or flexible?
Can it seal cracks that are leaking water?
How is it applied on site?
Why choose PU 2K over an epoxy injection resin?
Is it safe to use in tunnels, tanks and enclosed spaces?
What pack sizes are available and can Space Arc supply pan-India?
How we position STP ShaliGrout PU 2K
ShaliGrout PU 2K is the flexible member of STP’s crack-injection line: reach for it when the crack moves and you need an elastic seal, and pair it with a water-reactive foaming grout from the same family to first arrest active leaks before the permanent seal goes in. Where the crack is static and the goal is to restore structural continuity, a rigid epoxy injection resin is the better tool. Within the wider Space Arc portfolio, we can cross-specify Fosroc’s crack-injection and Nitofill range, Sika’s injection systems and Dr. Fixit repair products so the resin is matched to the crack behaviour, not just the brand on the tin. Talk to our applicators for a joint crack survey.
Fosroc Nitofill UR63 — A specifier who wants a two-part, solvent-free flexible PU injection resin engineered for hot Indian climates and able to bond to damp crack faces may prefer the Fosroc option.
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