Fosroc Supercast Acrylate 300
Low-viscosity, three-component methacrylate (acrylate) injection gel for waterstopping concrete joints, cracks and membrane compartments — supplied and applied across Delhi NCR and Pan-India by Space Arc Engineering.
What is it?
A methacrylate-based, three-component (A1 resin, A2 catalyst, B1 water-diluted initiator) low-viscosity injection resin that reacts in-situ to form a flexible, hydrophilic elastic gel. It is part of Fosroc’s Supercast Acrylate injection range (100 / 200 / 300), not a gun-grade or pouring joint sealant.
Where is it used?
Pressure-injected into leaking construction and movement joints, cracks, segment/tubbing interfaces, and into the compartments behind sheet membranes such as Proofex Alkorplan in tunnels, basements, water-retaining structures and underground works.
Why use it?
Its water-like viscosity penetrates fine cracks and saturated ground that paste sealants cannot reach, while the cured gel swells reversibly on contact with water to maintain a watertight seal and can be re-injected through hose systems if leakage recurs.
How is it applied?
The three components are metered, mixed and pumped through a single- or two-component injection pump via packers, lances or pre-installed injection hoses (Supercast Predimax). Curing speed is adjustable; the gel forms in-situ within the joint, crack or membrane void.
About Fosroc Supercast Acrylate 300
Fosroc Supercast Acrylate 300 is a specialist waterproofing injection material rather than a conventional jointing sealant. It belongs to the Supercast Acrylate family — a range of methacrylate (acrylate) based hydrophilic injection gels that Fosroc supplies for sealing water ingress through concrete. The product is delivered as three separate components: an A1 resin, an A2 catalyst and a B1 initiator that is diluted with water on site. When these are combined in the pump line, an in-situ chemical reaction converts the thin, watery liquid into a soft, rubber-like elastic gel that fills and seals the void it has been injected into.
What sets the Acrylate 300 grade apart from a typical polyurethane, polysulphide or silicone sealant is how and where it works. It is not gunned into an open joint or poured into a horizontal slab gap. Instead, it is pumped under pressure into places that are already saturated or actively leaking — hairline cracks, honeycombed concrete, construction joints, segment and tubbing interfaces, and the narrow compartments that sit behind loose-laid sheet membranes. Because the un-reacted resin has a viscosity close to that of water, it travels into fissures and damp ground that paste-grade products simply cannot enter, then gels to block the flow path.
The cured gel is hydrophilic and dimensionally responsive: it absorbs water and swells, and the official Fosroc data notes the gel can absorb up to roughly twice its own weight when immersed. This swelling is reversible — the gel takes up water when wet conditions return and slowly contracts when the surrounding environment dries, while broadly retaining its volume under sustained humid conditions. In practice this means the seal “self-heals” against renewed water pressure rather than shrinking back and re-opening a leak path. For Indian projects — basements, metro and road tunnels, lift pits, STP/WTP tanks and water-retaining structures — this makes Acrylate 300 a remedial and pre-emptive curtain/permeation grout, complementing rather than replacing the gun-grade joint sealants in Fosroc’s Nitoseal and Thioflex ranges.
Space Arc Engineering, as an authorised Fosroc distributor and applicator, supplies Supercast Acrylate 300 along with the matching Supercast Predimax injection hose, packers and pumping equipment, and can advise on whether injection grouting or an open-joint sealant is the right specification for a given detail.
The technical insight
The defining technical property of Supercast Acrylate 300 is its near-water viscosity in the un-reacted state, which gives it a permeation and penetration capacity that paste sealants and even most polyurethane resins cannot match — it can travel through micro-cracks and into saturated sand or silt before it gels. The reaction chemistry is controllable: by adjusting the proportion and dilution of the B1 initiator and the A2 catalyst, the gel (cure) time can be tuned from very fast to slow to suit the leak rate and the distance the resin must travel. Unlike rigid PU foams, the product cures to a soft, highly elastic gel that tolerates minor ongoing movement and, critically, is hydrophilic — it swells reversibly on water contact (absorbing up to about twice its weight) so that the seal re-pressurises itself against returning groundwater instead of debonding. Within the range, the 100/200/300 grades share this methacrylate gel platform but differ in component formulation and intended duty; the 300 grade is specifically positioned by Fosroc for injection into membrane compartments (e.g. Proofex Alkorplan tunnel waterproofing systems) and for re-injectable joint sealing via the Supercast Predimax hose, where long-term re-treatment capability matters.
Where it is used
- Curtain/permeation injection to stop active water ingress through leaking concrete construction joints
- Sealing of cracks in concrete foundation piles, diaphragm walls, tubbings and tunnel segments
- Injection into the compartments behind loose-laid sheet membranes such as Proofex Alkorplan in tunnel waterproofing
- Pre-installed re-injectable joint sealing through Supercast Predimax injection hose systems
- Stabilisation and waterproofing of water-bearing sandy or silty soils adjacent to structures
- Large-area soil/ground sealing around tunnels, shafts and trench excavations
- Remedial waterproofing of basements, lift pits, car-park slabs and underground car parks
- Sealing of water-retaining and water-excluding structures such as tanks, reservoirs and STP/WTP elements
Key advantages
- Water-like viscosity gives excellent penetration into fine cracks, joints and saturated ground that paste sealants cannot enter
- Adjustable curing/gel speed allows the reaction to be tuned to leak rate and travel distance on site
- Cures to a flexible, highly elastic hydrophilic gel rather than a rigid mass
- Swells reversibly on contact with water, helping the seal re-pressurise itself against renewed ingress
- Re-injectable when used with Supercast Predimax injection hose for future re-treatment
- Good chemical resistance to most organic and inorganic liquids found in groundwater
- Suited to actively leaking, wet conditions where surface-applied or gun-grade sealants will not bond
- Backed in India by Space Arc Engineering for material supply, equipment and applicator support
Limitations & considerations
- Not a gun-grade or pouring joint sealant — it cannot be applied with a sealant gun into an open, visible joint and is not a like-for-like substitute for Nitoseal, Thioflex or Colpor
- Requires specialist injection equipment (metering pump, packers/lances or pre-laid hose) and trained operatives — not a DIY or simple hand-applied product
- Three-component metering and water dilution must be controlled accurately; incorrect ratios affect gel time and seal quality
- Performance depends on correct packer placement and injection pressure; voids or fast-flowing water can wash out resin before it gels
- As a below-grade injection grout it is not designed for exposed facade movement joints, trafficked floor-joint wear, or UV-exposed weather seals
- Verified published figures are limited to the Fosroc product page; project-specific gel time, pack sizes and dosage should be confirmed against the current local TDS before specification
Selection & best practice
Treat Supercast Acrylate 300 as an injection/grouting system, not an open-joint sealant — the “joint design” that matters here is the injection layout, not a width-to-depth ratio. Survey the leak to locate the water path, then drill and fit packers (or use a pre-installed Supercast Predimax hose) at a spacing close enough that adjacent injection points overlap. Always inject from the lowest point upward and from the downstream side toward the water, so the gel is driven into the flow path. Carry out a trial dosage to calibrate the gel time: it should be slow enough for the resin to travel into the crack or compartment, but fast enough to set before fast-moving water dilutes or washes it out — adjust the B1 initiator/A2 catalyst proportions accordingly. Keep the three components correctly metered and the B1 dilution water clean and at a controlled temperature. Flush the pump and lines with water immediately after use, since the resin will gel inside equipment. For permanent movement or expansion joints that are dry and accessible, specify a gun-grade elastomeric sealant (e.g. Fosroc Nitoseal or Thioflex with the correct backer rod, primer and movement accommodation factor) instead of, or in combination with, injection. Always confirm components, gel time and pack sizes against the current Fosroc TDS for your region before ordering.
Specifications
| Product type | Methacrylate (acrylate) based three-component injection resin / hydrophilic gel |
| Function | Waterstopping / leak-sealing injection grout for joints, cracks and membrane compartments |
| Components | Three: A1 (resin), A2 (catalyst), B1 (initiator, diluted with water on site) |
| Cured form | Soft, flexible, elastic hydrophilic gel formed by in-situ reaction |
| Viscosity (un-reacted) | Water-like / very low — for high penetration into fine cracks and saturated ground |
| Cure / gel time | Adjustable (controlled via catalyst/initiator dosage) to suit leak rate and travel distance |
| Water absorption | Gel can absorb up to approx. 2x its own weight when immersed in water |
| Swelling behaviour | Reversible swelling on moisture contact; broadly volume-stable under sustained humid conditions, slow contraction when dry |
| Chemical resistance | Resistant to most organic and inorganic liquids |
| Re-injectability | Re-injectable when used with Supercast Predimax injection hose |
| Application method | Pressure injection via metering pump and packers/lances or pre-installed injection hose |
| Product range | Part of Fosroc Supercast Acrylate injection range (Acrylate 100 / 200 / 300) |
| Typical structures | Tunnels, basements, lift pits, water-retaining and below-grade concrete structures |
Industry use cases
Metro & road tunnels
Injection of the acrylate gel into Proofex Alkorplan membrane compartments and into leaking segment/tubbing joints to seal water ingress in driven and cut-and-cover tunnels.
Basements & deep foundations
Remedial curtain and crack injection in diaphragm walls, raft slabs, pile heads and lift pits where the structure is below the water table and surface sealants cannot bond.
Water & wastewater (STP/WTP, tanks, reservoirs)
Sealing of construction joints and cracks in water-retaining and water-excluding concrete, using a flexible gel that re-swells against hydrostatic pressure.
Underground car parks & podiums
Stopping live leaks at construction joints and through-slab cracks where excavation to re-waterproof the deck externally is not feasible.
Ground stabilisation around excavations
Permeation injection to seal and stabilise water-bearing sandy or silty soils next to shafts, trenches and tunnel portals before or during excavation.
Re-injectable joint systems (new build)
Combined with pre-installed Supercast Predimax hose in new construction joints, allowing the joint to be sealed — and later re-sealed — by injection without breaking out concrete.
Frequently asked questions
Is Fosroc Supercast Acrylate 300 a normal joint sealant like silicone or polyurethane?
What chemistry is Supercast Acrylate 300 based on?
How is it applied on site?
How does it actually stop water?
How does Acrylate 300 differ from Acrylate 100 and 200?
Can Space Arc Engineering supply and apply it in India?
How we position Fosroc Supercast Acrylate 300
Fosroc Supercast Acrylate 300 sits firmly in the waterproofing injection / waterstop family rather than the conventional jointing-sealant family, which is the key thing for specifiers to understand. It is the right choice when concrete is already wet or leaking — cracks, construction joints, tubbing interfaces and membrane compartments below grade. It is best paired with related Fosroc products: Supercast Predimax injection hose for re-injectable joints, and the wider Supercast waterstop range (PVC and hydrophilic strips) for new joints. Where the requirement is actually an exposed, dry, movement-accommodating joint seal, the better Fosroc options are the gun-grade elastomerics — Nitoseal (polyurethane/MS), Thioflex 600 (polysulphide) and Colpor 200PF (pavement-grade) — not an injection resin. Among injection products, Fosroc’s own Acrylate 100/200 grades and PU resins (e.g. Conbextra/Nitofill PU systems) are direct relatives. Credible competitor injection systems used in India include the Sika acrylic/PU injection range (e.g. Sika Injection acrylic gels and SikaFix PU), MBCC/Master Builders Solutions MasterInject and MasterSeal injection resins, and Pidilite Dr. Fixit / STP polymer-modified systems for related waterproofing scopes. Choosing between them comes down to leak rate, flexibility, re-injection needs and potable-water contact — areas where Space Arc Engineering can advise on a like-for-like specification.
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