About MC-Bauchemie MC-Injekt 2133

MC-Injekt 2133 is a one-component, low-viscosity polyurethane elastomer resin built for exactly one job: shutting off flowing water fast, so a crew can actually get near the problem. It ships ready to use — no mixing, no pot-life clock ticking the moment you open the drum — and stays workable indefinitely as long as it never touches water. The instant it meets a water-bearing crack, joint, or seepage path, it starts reacting within roughly 10-15 seconds and reaches full reaction in about 60-70 seconds, foaming up to around 3,000% of its original volume under free-foaming conditions. That expansion is what physically chokes off the water path, even against active pressure, buying time for the real repair to happen in a drier, calmer environment.

It’s worth being upfront about what this product is not: MC-Bauchemie itself is explicit that MC-Injekt 2133 is a temporary sealing measure, not a permanent structural waterproofing solution. On any site where we specify it — tunnel linings, sewage structures, basement raft slabs, retaining walls, building-pit shoring — the sequence is always the same: knock down the active flow with 2133, then follow up with a permanent elastomer resin such as MC-Injekt 2300 top or MC-Injekt 2300 flow once the substrate is dry enough to bond properly. Treating 2133 as the finished repair is the single most common misuse we see on Delhi NCR sites, usually from contractors trying to save a mobilisation trip.

The technical insight

The behaviour that matters here is the split between “processing time” and “reaction time” — and they’re governed by two completely different triggers. Processing time (how long the resin stays usable in the pump before you inject it) is effectively unlimited as long as it never contacts water; reaction time (10-15 seconds to start, 60-70 seconds to finish) only begins once it does. That’s a deliberate design choice for emergency work: a crew can prime the pump, walk the line, and hold the resin ready without racing a countdown clock, then get a genuinely fast set the moment it hits the leak. The ~3,000% free-foam expansion figure is measured without backpressure in lab conditions at 21°C ± 2°C — real-world expansion against confined, pressurised water will be lower, which is exactly why a trial injection matters before committing to full-scale pumping on an unfamiliar leak. The MC-KAT 20 catalyst option exists for the same reason contractors reach for accelerators generally: high-pressure or high-flow leaks can wash uncatalysed resin away before it gets the chance to react.

Where it is used

• Emergency shut-off of actively flowing or pressurised water in construction joints, cracks, and cold joints
• Stopping water leakages in water-retaining and sewage/STP structures before permanent repair
• Temporary sealing of heavily water-bearing cracks ahead of permanent injection with MC-Injekt 2300 top or 2300 flow
• Pre-sealing of building-pit closures and shoring walls where groundwater is actively entering the excavation
• Tunnel lining and segment-joint leak arrest during construction and post-construction maintenance
• Foundation-soil consolidation where a running water path needs to be choked before grouting proceeds
• Basement and retaining-wall leak control on occupied buildings where dry working conditions are needed fast
• Lift-pit and sump leak stoppage where water ingress is preventing waterproofing works from starting

Key advantages

• Reacts in seconds on contact with water — genuinely useful when you’re standing in an active leak and need it stopped now, not after a cure cycle
• Unlimited pot life before water contact means the resin can sit primed in the pump and hose for hours without wasting material
• Low viscosity (~400 mPa·s) lets it penetrate fine, hairline water-bearing cracks that thicker grouts can’t reach
• Massive volume expansion (~3,000% free-foam) fills irregular voids and running joints without needing precise dosing
• Phthalate plasticiser-free formulation, which matters for water-contact and sewage-structure specifications
• Works as a genuine 1-component system with standard piston pumps (e.g. MC-I 510) — no metering ratio to get wrong on site
• Reaction speed is tunable with MC-KAT 20 catalyst, useful when water flow is aggressive and you need a faster set
• Backed by an MC-Bauchemie Environmental Product Declaration (EPD), useful for green-building and CPWD documentation asks

Limitations & considerations

• Explicitly a temporary sealing measure — not rated for permanent sealing against pressurised water, so a follow-up injection is always required
• Won’t react at all on dry substrates; the area being injected must contain water, which sometimes means pre-wetting first
• Application must stop below 5°C component/substrate temperature, ruling out early-morning winter work in North India without warming the substrate
• Reacts almost immediately on water contact, which leaves little room for error in packer placement or pump timing on a fast-moving leak
• Light brown colour and foam texture aren’t cosmetically finished — this is a functional shut-off layer, not a visible repair surface
• Equipment must be cleaned with MC-Verdünnung PU thinner, never water — any moisture in the lines during cleaning will set resin inside the pump

Selection & best practice

Specifications

Industry use cases

How we position MC-Bauchemie MC-Injekt 2133

Within Space Arc’s MC-Bauchemie injection range, MC-Injekt 2133 is deliberately positioned as the “stop the bleeding” resin, not the finished repair — it’s designed to be specified alongside MC-Injekt 2300 top or MC-Injekt 2300 flow, MC-Bauchemie’s permanent elastomer sealing resins, which go in once the active flow is arrested and the substrate can be worked properly. On sites also using MC’s acrylate or epoxy injection lines for structural crack bonding, 2133 is purely the emergency-response step before those materials can even be applied. Against the wider market, Fosroc’s Nitofill PU 1R covers similar ground as a single-component hydrophobic PU crack-injection grout, and specifiers occasionally weigh it against Sika’s and BASF Master Builders’ polyurethane injection lines too — the functional category (fast-reacting, water-triggered PU foam) is well established across brands. Space Arc stocks and applies the MC-Bauchemie range as an authorised distributor and applicator, and can quote either the MC or Fosroc route depending on what’s already specified on the project.

Related Waterproofing products

View all Waterproofing products →