About MC-Bauchemie MC-Montan Injekt DR

Most waterproofing conversations start with membranes and coatings, but a good share of real leaks show up where those cannot reach: a hairline fissure behind a tunnel lining, a construction joint below the water table, a manhole ring joint that has quietly opened after a few monsoons of ground movement. MC-Montan Injekt DR belongs to the two-component polyurethane elastomer resins MC-Bauchemie built specifically for injection into rock, soil and structural cavities under wet or pressurised conditions. It does not fight water, it displaces it. At only about 55 mPa·s viscosity and low surface tension, the resin travels into fissures far finer than a cementitious grout can reach, and because it does not foam on contact with moisture, it forms a dense, pore-filling seal rather than a spongy mass full of voids.

For Space Arc’s project base across Delhi NCR and pan-India metro, dam and sewerage work, that distinction matters more than it would in ordinary building waterproofing. Underground structures move: tunnels flex under traffic and seismic load, dam joints breathe with reservoir level, manhole rings settle unevenly in saturated soil. A rigid sealant tends to re-crack at the same spot within a season. Tested to roughly 100% free elongation and 11-17% strain within an active crack, and ductile down to -34°C, MC-Montan Injekt DR is built to move with the structure rather than fight it — the specific gap it is meant to close.

The technical insight

The chemistry is a two-component polyurethane elastomer, not a rigid PU foam and not an epoxy. Components A and B are pumped in equal volumes, roughly 100:111 by weight, through an inline static mixer and injected while still liquid. DR reacts in about 4 minutes while its sibling DS takes roughly 100 minutes, and blending A-components from each lets an applicator dial in the exact working time a given hole spacing, water flow and pump distance calls for — which is why specifiers usually order DR and DS together rather than DR alone. The EN 1504-5 CE marking and the DIBt approval for injection into soil and groundwater are what separate this from a generic hardware-store PU foam: EN 1504-5 covers concrete-repair injection systems specifically, and DIBt is Germany’s own regulatory sign-off for putting a reactive resin directly into ground that may feed drinking-water aquifers — a bar most crack-sealing products never have to clear.

Where it is used

• Sealing water-bearing rock fissures encountered during tunnel drives and drill-and-blast headings
• Subsoil and loose-rock consolidation ahead of shaft sinking, foundation excavation or TBM passage
• Waterproofing dams, weirs and barrages at construction joints and rock contact zones
• Sealing pipe and liner penetrations into manhole and shaft structures in sewerage infrastructure
• Injection sealing of manhole ring joints and socket joints prone to groundwater infiltration
• Running-crack and construction-joint injection in water-retaining concrete under active leakage
• Hybrid cement-PU consolidation grouting where ground permeability varies within one injection zone

Key advantages

• Displaces water rather than foaming against it, staying reactive even in flowing or pressurised water
• Ductile, about 100% free elongation and a glass transition of -34°C, tolerating structural movement instead of re-cracking
• Reaction time is field-tunable by blending fast-reacting DR with slower sibling DS to match hole spacing and water flow
• Tested pressure-water tightness of 7 bar under EN 14068 gives real margin against deep hydrostatic heads
• CE-marked to EN 1504-5 and DIBt-approved for soil and groundwater injection — documentation metro and PWD consultants ask for
• Can be hybridised with cement suspension for combined consolidation and sealing in mixed-permeability ground
• Low viscosity and surface tension give penetration into hairline fissures that thicker cementitious or epoxy grouts cannot reach

Limitations & considerations

• Needs a proper two-component metering pump such as the MC-I 700/710 and a trained packer-setting crew; it is not a hand-mixed product
• Reaction time is temperature sensitive, application must stop below 5°C, and published values are lab-referenced to 21°C ± 2°C
• Tools need solvent-based MC-Verdünnung PU thinner only; water or aqueous cleaners are explicitly ruled out and cured resin must be removed mechanically
• An elastomeric sealing and consolidation resin, not a structural strengthening system — it does not restore load-bearing section
• Outcomes depend heavily on the upfront leak investigation and trial injection the datasheet calls for; skipping that step is the most common cause of underperformance on site

Selection & best practice

Specifications

Industry use cases

How we position MC-Bauchemie MC-Montan Injekt DR

MC-Montan Injekt DR sits inside a deliberately modular MC-Bauchemie family rather than standing alone. Its direct sibling is MC-Montan Injekt DS, the slow-reacting component meant to be blended in for longer working times, and MC-Montan Injekt LE covers lower-viscosity variants of the same subsoil-injection line. Where the requirement shifts from ductile, water-displacing sealing to rigid, load-transferring structural crack repair, the same manufacturer’s MC-Injekt 2K PU, MC-Injekt 1K, MC-Injekt 2200, 2600, 640 and FS resins are the more appropriate specification, and Space Arc stocks that range alongside this one. The MC-I 700/710 pumps and MC-Bore Packer LS 18 packers named in the datasheet are the same accessories used across the whole MC-Montan and MC-Injekt lines. Space Arc’s Fosroc range does not currently carry a genuine equivalent — Fosroc’s crack-injection offering leans towards bituminous joint sealants rather than elastomeric PU rock and soil injection resins with DIBt groundwater approval. Where a specifier wants a cross-brand comparator, Sika’s Injection-201 IN elastic PU crack-injection resin is closer, though it is scoped to concrete cracks and joints rather than the full rock, subsoil, dam and tunnel injection range MC-Montan Injekt DR is approved for.

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