About MC-Bauchemie MC-Inject 1K

MC-Inject 1K is MC-Bauchemie’s single-component polyurethane grout for one of the most stubborn problems on any waterproofing site: a crack or joint that is already leaking. Most repair resins want a dry substrate. This one wants the opposite. It is an isocyanate-based prepolymer supplied ready for use, and it stays inert in the container until it meets moisture. The instant it contacts water inside the crack, it reacts, releases gas and foams, expanding several times its liquid volume to fill the void and choke off the flow. Because there is no second component to measure, the common failure mode of two-part systems, an incorrect mix ratio, simply does not exist here.

For engineers and applicators working across Delhi NCR and pan-India, that single-component nature is the practical draw. A crew can arrive at a live seepage, set packers, and pump straight from the container with a 1K injection unit. The cured foam is flexible rather than brittle, so it tolerates the small seasonal and thermal movements that reopen rigid repairs. MC-Inject 1K is frequently used as a fast first line of defence to arrest heavy inflow, after which a permanent elastic resin can be injected into the same crack under controlled, now-drier conditions. Space Arc Engineering supplies and applies it as an authorised MC-Bauchemie channel partner, with technical support on packer layout and injection sequencing.

The technical insight

The chemistry is deliberately water-triggered. MC-Inject 1K is a moisture-reactive isocyanate prepolymer: on contact with water the isocyanate groups react, evolving carbon dioxide that blows the resin into a cellular foam. That reaction does two useful things at once. First, the gas expansion drives the resin outward into hairline branches and honeycombed concrete that a non-foaming grout would never reach, so the seal follows the water rather than stopping at the packer. Second, the volume increase generates pressure inside the crack, pressing the curing foam tight against the crack walls. The result is a flexible, closed-cell polyurethane that keys mechanically into the substrate. Expansion is governed by how much water is present, which is why the same resin can be tuned from a modest gap-filling swell to an aggressive high-volume foam simply by the wetness of the crack; a genuinely dry crack must be pre-wetted with water for the resin to react at all. The low viscosity lets it travel into tight cracks before it foams, and because a moisture skin forms on any exposed resin surface, the material below stays protected and continues to cure in depth.

Where it is used

• Sealing actively leaking cracks in basement and retaining walls where water is already seeping
• Stopping strong water inflow through construction joints in water-retaining structures
• Emergency water stop in tunnels, shafts and lift pits ahead of permanent injection
• Waterproofing cracks in below-ground concrete and masonry under damp or running conditions
• Sealing annular gaps around pipe and service penetrations through walls and slabs
• Curtain and void filling behind leaking masonry and rubble walls
• First-stage arrest of heavy seepage before a permanent elastic resin is injected
• Crack and joint injection in water tanks, sumps and STP structures

Key advantages

• Single-component and ready to use, so there is no mix ratio to measure or get wrong on site
• Cures with water instead of against it, sealing live leaks that epoxy resins cannot handle
• Foams and expands several times its volume to chase water into fine and branching cracks
• Flexible closed-cell foam tolerates minor thermal and structural movement without cracking
• Low viscosity penetrates tight cracks before the foaming reaction begins
• Works from a standard single-component injection pump with common drill-in packers
• Long, stable shelf life while the container stays sealed and dry
• Fast reaction gives a rapid, visible water stop during emergency works

Limitations & considerations

• The crack must contain water; genuinely dry cracks have to be pre-injected with water to trigger the reaction
• Foam expansion is moisture-dependent, so results vary with how wet the crack actually is
• Often a temporary or first-stage water stop; permanent sealing against pressurised water may need follow-up injection with an elastic resin
• Not a structural crack-bonding resin, so it does not restore load transfer the way a rigid epoxy grout does
• Requires a single-component injection pump, packers and trained operators, not a brush-and-go product
• Any water or aqueous cleaner ruins uncured resin and equipment; only PU thinner should be used for cleaning

Selection & best practice

Specifications

Industry use cases

How we position MC-Bauchemie MC-Inject 1K

MC-Inject 1K sits at the single-component, get-it-stopped-fast end of MC-Bauchemie’s injection range. When the priority shifts from arresting inflow to a durable elastic seal against pressurised water, pair it with an elastic follow-up resin from the MC-Injekt 2300 family, the standard permanent partner for this kind of two-stage water stop. For structural, non-moving cracks that need load transfer rather than a flexible foam, an epoxy injection grout is the right tool instead. Buyers who prefer to stay within the Fosroc ecosystem, or who need a comparable two-component water-reactive PU, should look at Fosroc Nitofill UR63, which we also supply and apply. Space Arc stocks MC-Bauchemie alongside Fosroc, Sika, Dr. Fixit and other leading brands, so we can match the resin to the leak rather than to a single catalogue.

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