About MC-Bauchemie MC-Injekt 2300 NV

MC-Injekt 2300 NV is MC-Bauchemie’s standard-pot-life flexible polyurethane gel for injecting cracks that move — the kind of hairline fracture that opens a shade wider every summer and closes again every monsoon, and that a rigid epoxy fill would eventually re-crack. It’s a two-component, solvent-free resin with a genuinely low viscosity (around 100 mPa·s), which is what lets it work its way into cracks as fine as 0.1 mm rather than just sitting in the wider ones. Because it’s part of a wider MC-Bauchemie injection system — usually installed through drilled packers with a calibrated two-part pump — it’s a specialist-applicator product rather than a DIY tube-and-caulk-gun job, which is exactly the segment Space Arc’s site crews are set up to execute.

What sets the NV grade apart on an Indian below-grade waterproofing job is the combination of two things most rigid injection resins can’t offer together: it stays soft and elastic (Shore A around 50, elongation over 100%) long after cure, so it keeps sealing a joint that’s still moving; and it accelerates in contact with water rather than being washed away by it, which matters on a basement or UG sump crack that’s actively weeping during a monsoon site visit. It’s also one of the few resins in this category carrying a German KTW listing for potable-water contact, which specifiers ask for directly on OHT, UG water-tank and WTP structures. The trade-off is that it isn’t a strength-restoring repair — for cracks tied to genuine structural distress, a rigid structural epoxy injection is the correct call, and 2300 NV should be reserved for movement joints and non-structural leak paths.

The technical insight

The chemistry worth understanding before specifying this over a rigid epoxy is the cure mechanism itself. MC-Injekt 2300 NV is a hydrophobic-reactive polyurethane gel: it doesn’t foam aggressively on contact with water the way a fast-reacting PU foam does (volume increase is a modest, controllable 10-20% at 5% water contact) — instead it gels into a dense, closed-cell elastomer that bonds to damp crack faces and simply stays flexible. That’s why MC-Bauchemie sequences it behind a different product, MC-Injekt 2133, on cracks with active flowing or pressurised water: 2133’s job is to foam fast and stop the flow first, and 2300 NV goes in afterward through the same packers to give the crack a permanent, movement-tolerant seal. Treating 2300 NV as a one-shot fix for a running leak, without that pre-injection stage, is a common site mistake that leads to callbacks.

Where it is used

• Sealing moving hairline cracks (0.1 mm and above) in below-grade RCC walls, raft slabs and retaining walls
• Flexible sealing of construction and movement joints subject to thermal or settlement movement
• Water-tightening potable-water structures — underground sumps, OHTs, WTP and STP tanks — where KTW compliance is specified
• Leak sealing in lift pits, tunnels, culverts and diaphragm/shear walls
• Final sealing injection after a pre-injection stage (with a fast-foaming PU such as MC-Injekt 2133) has stopped active water flow
• Non-structural crack repair where restoring load-bearing continuity isn’t the requirement
• Sealing cold/construction joints in basements and water-retaining structures
• Retrofit leak-stopping through drilled packers without breaking open finished slabs or walls

Key advantages

• Elongation over 100% means the seal keeps working through repeated crack movement instead of re-cracking like a rigid fill
• Genuinely low viscosity (about 100 mPa·s) penetrates hairline cracks down to roughly 0.1 mm
• Reacts faster in the presence of water, so active seepage accelerates the seal rather than defeating it
• Controlled, modest expansion (10-20% at 5% water contact) gives predictable results compared with aggressive foaming resins
• Bonds to damp and wet crack faces — doesn’t demand a bone-dry substrate the way many epoxies do
• KTW-listed for drinking-water contact, which simplifies sign-off on OHTs and UG tanks
• About 100 minutes of working time at 20°C gives crews room to re-inject and fully saturate the crack before it gels
• Comes from a manufacturer with a long, specific track record in structural and tunnel injection systems

Limitations & considerations

• Not a structural repair — it won’t restore load-bearing continuity, so genuine structural cracks need a rigid epoxy injection instead
• Working time and gel time shorten sharply in Indian summer site temperatures, so mixed batches and crew pace need planning around ambient heat
• Needs a calibrated two-component pump, packers and a trained crew — it isn’t a pour-and-hope product
• Minimum application temperature is 3°C, which rules out very early-morning winter work at high-altitude sites
• Once cured, the gel can only be removed mechanically, so tools and pump lines must be flushed with the manufacturer’s cleaning solvent before it sets
• Shelf life is 12 months from manufacture stored cool and dry, so it should be bought against a live job rather than held as long-term stock

Selection & best practice

Specifications

Industry use cases

How we position MC-Bauchemie MC-Injekt 2300 NV

MC-Injekt 2300 NV sits alongside MC-Injekt 2133 (the fast-foaming resin used to pre-stop active water flow) and the newer MC-Injekt 2300 top/flow variants in MC-Bauchemie’s injection-systems range — all designed to be run through the same packers as part of one sequenced repair rather than picked in isolation. For rigid, load-bearing crack repair, the correct comparison isn’t within this flexible-gel family at all but a structural epoxy injection resin. On the competitive side, specifiers who’ve standardised on Fosroc’s injection range, or who don’t need the KTW potable-water listing, often reach for Fosroc Nitofill UR63 instead — a genuinely comparable two-part flexible PU resin for moving, wet cracks. Space Arc stocks and applies both brands, so the honest answer on which to use usually comes down to whether the job needs KTW compliance and which brand the rest of the waterproofing package is already specified in.

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