STP ShaliGrout EI
A moisture-insensitive, two-component epoxy injection grout that penetrates hairline cracks and structurally re-bonds concrete back to a monolithic whole.
What is it?
A 100% reactive, solvent-free two-part epoxy injection grout from STP, engineered at very low viscosity to travel deep into fine structural cracks and cure to a rigid, load-bearing bond.
Where is it used?
Cracked RC beams, columns, slabs and shear walls; bridge decks and piers; foundations; and delaminated or honeycombed concrete needing structural re-bonding.
Why use it?
It restores monolithic strength across a crack rather than merely sealing it, and because it is moisture-insensitive it bonds even to damp concrete where ordinary epoxies fail.
How is it applied?
Ports are fixed along the crack, the surface is sealed, the two components are mixed and the resin is pressure-injected port-to-port until refusal, then left to cure undisturbed.
About STP ShaliGrout EI
ShaliGrout EI is STP’s low-viscosity epoxy resin system for the structural repair of cracked concrete. Unlike a surface sealer or a flexible joint filler, it is designed to be forced into the crack under pressure so that the resin wets both faces and cures into a rigid adhesive that carries load across the fracture. Once cured it develops a compressive strength above 70 MPa, comfortably exceeding the strength of the parent concrete, which is why the repaired section behaves as a single monolithic element again rather than as two pieces held loosely together.
What makes the product genuinely useful on Indian sites is its tolerance of moisture. Cracks in foundations, water tanks, basement rafts and monsoon-exposed structures are rarely bone-dry, and most epoxies refuse to bond to a damp substrate. ShaliGrout EI is formulated to remain effective on damp concrete, so contractors are not forced to wait days for a crack to dry out before they can inject it. The resin is 100% reactive with no solvent and no VOC emission, meaning there is no shrinkage from solvent loss and the injected volume stays put inside the crack as it cures.
The technical insight
The repair works because of capillary action combined with injection pressure. A crack as fine as 0.05 to 0.1 mm has enormous surface tension resisting entry, so the resin has to be both very low in viscosity and pushed under pressure to migrate the full depth of the fracture. ShaliGrout EI is built as a super-low-viscosity, high-modulus system for exactly this: thin enough to wick into hairline cracks, yet rigid enough once cured to transfer stress rather than flex under it. Because the cured resin is stronger than the surrounding concrete, any future overload tends to crack the concrete afresh elsewhere rather than reopen the glued line, which is the defining test of a successful structural injection. The moisture-insensitive chemistry is the other half of the story: the resin displaces or bonds through the thin water film on the crack walls instead of being repelled by it, so adhesion is achieved on substrates that would defeat a standard epoxy.
Where it is used
- Pressure injection of structural cracks in RC beams, columns and slabs
- Re-bonding of cracks in shear walls and load-bearing masonry
- Crack repair in bridge decks, piers and abutments
- Sealing and re-bonding of cracks in foundations and pile caps
- Injection of damp or water-affected cracks in basements and retaining walls
- Filling of honeycombed, voided or delaminated concrete pockets
- Rehabilitation of cracks in water-retaining and marine structures
- Structural repair of cracked concrete in industrial floors and machine bases
Key advantages
- Restores full monolithic structural strength across the crack, not just a surface seal
- Very low viscosity penetrates hairline cracks down to 0.05-0.1 mm
- Moisture-insensitive, so it bonds reliably to damp concrete
- Cured compressive strength above 70 MPa, exceeding typical parent concrete
- 100% reactive with no solvent and no VOC, so there is no shrinkage on cure
- High adhesive strength to both concrete and embedded steel
- Two-component system with a fixed, easy-to-batch mix ratio
- Suitable across a wide range of Indian site and climate conditions
Limitations & considerations
- Designed for dormant cracks; not a substitute for a flexible sealant on live, moving cracks or expansion joints
- Cured resin is rigid and high-modulus, so it will not accommodate ongoing structural movement
- Not intended for injection against actively running water without first arresting the flow
- Requires trained operatives, injection ports and pressure equipment to place correctly
- Two-part epoxy must be mixed at the specified ratio and used within its working time
- Very wide cracks or large voids may be better suited to a gel or thixotropic grade rather than this low-viscosity resin
Selection & best practice
Rout out and clean the crack, then fix injection ports (nipples) along its length at spacings suited to the member thickness, and seal the surface between ports with a fast-setting epoxy paste so the resin cannot bleed out. Mix the resin and hardener thoroughly at the stated ratio, in batches you can inject within the working time, and pump from the lowest port upward (or end to end on horizontal members) until resin appears at the next port, then move on. Keep injection pressure controlled and steady to let the low-viscosity resin migrate to full depth rather than blowing the surface seal. Cap each port as it refuses, leave the repair to cure fully undisturbed before removing ports and grinding the surface seal flush. On damp substrates the product still performs, but free-flowing water must be stopped first. Always confirm mix ratio, working time and cure time against the current STP technical data sheet for the batch supplied.
Specifications
| Product type | Two-component epoxy injection grout |
| Base chemistry | 100% reactive epoxy, solvent-free / no VOC |
| Compressive strength | > 70 MPa |
| Crack penetration | Down to 0.05-0.1 mm |
| Moisture sensitivity | Insensitive; bonds to damp concrete |
| Application method | Low-pressure resin injection |
| Mix ratio (per 2 L pack) | Resin 1.70 kg : Hardener 0.30 kg |
| Pack size | 2 litre can |
Industry use cases
Infrastructure & bridges
Re-bonding flexural and shear cracks in bridge decks, piers and abutments to restore load path and durability.
Commercial & residential buildings
Structural crack injection in RC beams, columns and slabs after overload, settlement or seismic distress.
Water-retaining & basement structures
Sealing and re-bonding cracks in rafts, retaining walls and tanks where the substrate stays damp.
Industrial facilities
Repair of cracked machine bases, industrial floors and voided or honeycombed concrete pockets.
Seismic rehabilitation
Restoring monolithic behaviour to distressed RC frames as part of a strengthening scheme.
Frequently asked questions
Can ShaliGrout EI be injected into damp cracks?
How fine a crack can it penetrate?
Does it actually restore structural strength, or just seal the crack?
Is it suitable for live or moving cracks?
What pack size and mix ratio does it come in?
Do I need special equipment to apply it?
How we position STP ShaliGrout EI
ShaliGrout EI sits in STP’s structural-repair range as the low-viscosity crack-injection resin. Where the crack is too wide or the void too large for a free-flowing resin, step up within the STP family to a thixotropic or higher-build ShaliGrout grade; where the surface first needs an epoxy sealing paste to hold injection ports, pair it with an STP epoxy putty. For strengthening that goes beyond re-bonding a crack, such as section enlargement or overlay, follow up with an STP structural repair mortar. Across our other brands we can also supply carbon-fibre or steel-plate bonding systems where the assessment calls for added structural capacity rather than crack repair alone. Our engineers can help match the right grade to the crack width, substrate condition and structural intent before you order.
Fosroc Nitofill EPLV — A specifier standardised on Fosroc, or working on a hot-climate site where the resin must stay workable at high ambient temperatures, may prefer Nitofill EPLV as the directly equivalent low-viscosity epoxy injection resin.
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