MC-Bauchemie MC-Injekt 1K
Single-component, moisture-triggered polyurethane injection resin that foams on contact with water to shut down active leaks in cracks, cold joints and below-grade concrete.
What is it?
A low-viscosity, single-component polyurethane injection resin from MC-Bauchemie that needs no separate hardener. It reacts with the moisture already present in a leaking crack and expands into a closed-cell foam that physically blocks the water path.
Where is it used?
Actively leaking cracks, cold joints and construction joints in basements, retaining walls, tunnels, lift pits, water tanks, utility ducts and other below-ground concrete structures across Delhi NCR and pan-India projects.
Why use it?
It works in wet, running-water conditions where two-part epoxies cannot cure, and its single-pack format removes the mixing-ratio errors that cause on-site injection failures.
How is it applied?
Injected under pressure through drilled packers spaced along the crack using a single-component pump; the resin travels into the crack, meets moisture, foams and seals from the inside out.
About MC-Bauchemie MC-Injekt 1K
MC-Injekt 1K belongs to MC-Bauchemie’s family of moisture-reactive polyurethane injection resins, engineered for the one job that trips up most repair crews: sealing a crack that is already weeping or gushing water. Conventional structural epoxies need a dry, stable substrate to bond and cure, so on a live leak they simply wash out. This resin flips that logic on its head. It is a ready-to-use, single-pack liquid built around a water-reactive isocyanate prepolymer, and it treats the moisture in the crack not as an enemy but as the trigger for its own chemistry. Pumped into the fissure, it reacts within seconds, expands, and locks the leak path with a tough closed-cell foam.
For contractors and site engineers, the single-component nature is the headline benefit. There is no Part A and Part B to weigh out, no 5:1 or 10:1 ratio to get wrong under pressure on a wet basement wall at the end of a shift. That reliability, combined with a low injection viscosity that lets the resin chase hairline cracks deep into the section, is why moisture-reactive PU has become the default first response for active water ingress. At Space Arc Engineering we supply MC-Injekt 1K alongside the packers, pumps and follow-up elastomer resins needed to turn an emergency leak into a durable, documented repair.
The technical insight
The resin is a pre-polymerised, water-reactive polyurethane. When it contacts free water in the crack, the isocyanate groups react with the water, cross-linking the polymer chains and liberating carbon dioxide gas in the same step. That released gas is what drives the expansion: the liquid froths up into a closed-cell foam, and it is this in-situ volume increase that lets a modest injected quantity fill and pressurise an irregular crack profile, sealing against the flow rather than just coating the walls. Because the reaction is moisture-driven, the wetter and more active the leak, the faster and more vigorously the resin sets. Reaction begins within roughly 10 to 15 seconds of water contact and is essentially complete inside about a minute, so the leak is stopped quickly while the pump still has access. In the sealed can, with no water present, the resin stays stable and ready to use, which is what gives it its long shelf life and forgiving working window on site.
Where it is used
- Sealing actively leaking cracks in basement retaining walls and base slabs
- Stopping water ingress at cold joints and construction joints in below-grade concrete
- Crack and joint sealing in tunnel linings and underground structures
- Leak remediation in lift pits, sumps and machine foundations
- Water-stopping in utility tunnels, cable trenches and pipe penetrations
- Emergency curtain injection behind leaking diaphragm and secant pile walls
- First-stage water stopping ahead of permanent flexible resin injection
- Sealing damp construction joints in water tanks and reservoirs (post-cure flushing where potable contact applies)
Key advantages
- Single-component: no mixing ratios, no proportioning errors, minimal on-site waste
- Reacts with the moisture already in the crack, so it seals wet and actively leaking substrates
- Low injection viscosity lets it penetrate fine and hairline cracks deep into the section
- Rapid foaming reaction stops running water within roughly a minute of contact
- Closed-cell foam gives an expanding, self-filling seal across irregular crack profiles
- Long shelf life in the sealed pack, with a forgiving working window before water contact
- Injected with a simple single-component pump, reducing equipment and setup on site
- Backed by MC-Bauchemie’s established injection system of packers, pumps and companion resins
Limitations & considerations
- Primarily a water-stopping resin, not a structural, force-transmitting crack repair — use an epoxy or rigid PU where load transfer is required
- Foam seal is best treated as a first-stage stop; permanently moving or high-pressure joints often need follow-up injection with a flexible elastomer resin
- Reaction depends on available moisture, so very dry cracks may need pre-wetting to trigger foaming
- Must be injected within the application temperature window (approx. +5 to +40 degrees C); work should stop when substrate temperature falls below 5 degrees C
- Cured or skinned material can only be removed mechanically; tools must be cleaned with PU thinner, never with water
- Requires trained operators and correct packer spacing and pressure to avoid incomplete fills or resin escape
Selection & best practice
Start with an injection concept: survey the crack, map the water path and set mechanical packers at roughly 200 to 300 mm centres along its length, staggering them either side on wider or deeper sections. Pump the resin on a single-component basis at a controlled 2 to 6 bar, adjusting for crack width and depth, and inject from the lowest packer upward so foaming resin displaces water as it climbs. Keep the storage container closed during the work to stop humidity skinning the resin, and do not let solid or reacted material enter the pump. On persistent or moving leaks, treat MC-Injekt 1K as the water-stopping first pass and follow up through the same packers with a flexible elastomer injection resin for a durable, movement-tolerant seal. Clean all equipment within the working time using MC-Bauchemie PU thinner — never water — and remove any set resin mechanically. Always work to the current technical data sheet and safety data sheet.
Specifications
| Product type | Single-component (1K), moisture-reactive polyurethane foam injection resin |
| Viscosity | Low viscosity, approx. 100-300 mPa.s at 20 degrees C |
| Density | Approx. 1.13 kg/dm3 |
| Reaction on water contact | Start approx. 10-15 sec; end approx. 60-70 sec |
| Volume expansion | Foams on water contact (high free-foam factor; multiple times injected liquid volume when confined) |
| Application temperature | +5 to +40 degrees C (component and substrate) |
| Colour | Light brown |
| Equipment cleaning | PU thinner / cleaner — do not use water or aqueous cleaners |
| Shelf life / storage | Approx. 18 months in sealed packs, stored dry at 5-35 degrees C |
Industry use cases
Basements & below-grade
Shutting down active leaks through wall cracks, base-slab cracks and construction joints in residential and commercial basements before internal finishing.
Tunnels & metros
Sealing water ingress at segment joints and lining cracks in tunnels, underpasses and metro structures where fast leak control keeps work fronts open.
Water-retaining structures
Stopping seepage through cracks and joints in tanks, reservoirs and STP structures, with post-cure flushing where potable-water contact is involved.
Industrial & infrastructure
Remediating leaks in lift pits, machine foundations, utility tunnels, cable trenches and pipe penetrations at plants and infrastructure sites.
Repair & rehabilitation contractors
A dependable single-pack first response for waterproofing crews handling emergency leak-sealing call-outs across Delhi NCR and pan-India projects.
Frequently asked questions
Can MC-Injekt 1K be injected into a crack that is actively leaking water?
Is it a single-component product, or do I need to mix two parts?
Does MC-Injekt 1K structurally repair the crack?
How is it injected and what packer spacing should I use?
How do I clean my equipment after use?
What pack size does it come in and how long does it keep?
How we position MC-Bauchemie MC-Injekt 1K
MC-Injekt 1K is the fast first-response water-stopper within MC-Bauchemie’s injection system. Once the leak is controlled, most specifiers follow up through the same packers with a flexible MC-Injekt elastomer resin (such as the MC-Injekt 2300 range) for a durable, movement-tolerant permanent seal, and pair it with MC-Bauchemie mechanical packers and a single-component injection pump. Where the crack must transmit load rather than just stop water, move to a rigid, force-transmitting PU or epoxy injection resin instead. Across our other brands, Space Arc also supplies comparable water-reactive PU grouts for teams standardised on Fosroc or Sika, so we can match the resin to the pump, packer and warranty regime the site already runs.
Fosroc Nitofill PU 1R — Choose the Fosroc option when the project or client is standardised on the Fosroc waterproofing system — it is likewise a single-component, water-reactive PU grout that foams to seal active leaks.
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