About MC-Bauchemie MC-Montan Injekt LE

MC-Montan Injekt LE is MC-Bauchemie’s fast-reacting, two-component polyurethane expansion resin built for one job: getting into ground or structures that are too loose, too wet, or too inaccessible for conventional grout, and turning them into a load-bearing, watertight mass within seconds. Comp. A and Comp. B are pumped separately and combined only inside a special 3K mixing head at the point of injection, in a fixed 1:2 ratio by volume; the mixture is tack-free in roughly 23-24 seconds and can expand to around 32 times its liquid volume as it reacts, actively displacing groundwater rather than being diluted or washed away by it. That combination of very fast set, high expansion, and indifference to moisture is what lets it consolidate weak subsoil down to about 10 m depth, raise bearing capacity under existing footings, physically lift and re-level settled structures, plug heavy water inflows in shafts and construction pits, and fill cavities up to 600 mm across — mostly through small-diameter lances rather than open excavation.

For Space Arc’s Delhi NCR and pan-India project base, the product earns its keep on ground that has already misbehaved: older structures on filled or reclaimed sites showing differential settlement, industrial floors and yards sinking over soft fill, basements and metro-adjacent excavations fighting monsoon-season water ingress, and sewage or utility lines leaking into surrounding soil faster than a cementitious grout can set around them. Because the reaction window is measured in single-digit seconds and the injection concept has to be engineered around a geotechnical report, we don’t sell MC-Montan Injekt LE as a retail pack — it is specified, planned by a structural engineer, and applied by trained injection crews using a proper two-component pump with rinsing unit and special mixing head, with the resulting ground movement monitored on site rather than assumed off a datasheet number.

The technical insight

MC-Montan Injekt LE is a genuine two-component expansion resin, not a slow-cure sealant dressed up for ground work — Component A (approx. 1.05 kg/dm³, ~265 mPa·s) and Component B (approx. 1.23 kg/dm³, ~210 mPa·s) are metered at a fixed 1:2 ratio by volume through a 3K mixing head that has to master an application time of just 4-5 seconds and a tack-free reaction time of 23-24 seconds, measured to ASTM D7/487. Those figures explain why it is strictly a pump-and-lance product: no crew can hand-mix a resin that sets in single-digit seconds. Once triggered, it can expand to roughly 32 times its liquid volume depending on the counter-pressure it meets in the ground — the actual lifting/consolidation mechanism is that the foam doesn’t simply fill loose soil, it compacts and displaces it outward and upward until the resistance of the overburden or the structure above stops the rise. It carries DIBt general building-inspectorate approval for injection into soil and groundwater and is rated building material class B2 to DIN 4102 in the injected medium — both details that matter when a structural engineer, not a site foreman, is signing off the lifting concept.

Where it is used

• Consolidation and compaction of loose or weak soil strata down to approximately 10 m depth beneath existing foundations
• Underpinning-free lifting and re-levelling of settled foundations, slabs and structures through controlled ground uplift
• Increasing the bearing capacity of subsoil under new or existing footings, industrial floors and trafficked pavement areas
• Emergency sealing of heavy, fast-flowing water inflows into construction pits, shafts and below-grade structures
• Sealing leaking sewage lines, utility trenches and manholes where a cementitious grout would be washed out before it sets
• Filling cavities and voids up to 600 mm diameter beneath slabs, roads and rail formations, without added aggregate
• Ground pre-treatment ahead of tunnel or mining drives for consolidation and water cut-off (Montan is German for mining)
• Curtain and compensation grouting around metro, basement and deep-excavation works to arrest ongoing settlement

Key advantages

• Very high expansion factor (approx. 32x, counter-pressure dependent) — a small injected resin volume compacts and displaces a large mass of weak soil
• Extremely fast reaction (4-5 sec application time, 23-24 sec tack-free per ASTM D7/487) so it grips and sets even in flowing groundwater instead of being washed out
• Volume increase works independently of the moisture content of the injection medium — no need to dewater the ground first
• Cures to a rigid, load-bearing, watertight hard foam that also dampens vibration once set
• Carries DIBt general building-inspectorate approval for injection into soil and groundwater, with REACH-assessed exposure data on file
• Avoids excavation, underpinning piles or structural downtime — work is done from small-diameter lance points around the structure
• Low relaxation / no ‘repression’ — the cured foam holds its set volume and pressure rather than settling back over time
• Rated building material class B2 to DIN 4102 in the injected medium

Limitations & considerations

• Requires a purpose-built 2K/3K injection pump with rinsing unit and special mixing head — it is not a hand-mixed or pourable product for casual site use
• Reaction is extremely fast (single-digit-second pot life), which is unforgiving of inexperienced operators and demands trained, certified injection crews
• A geotechnical report and a structural engineer’s sign-off on the lifting/consolidation concept are prerequisites — this is specialist ground-engineering work, not a general repair item
• Must be cleaned only with MC-Verdünnung PU within the application time; water or water-based cleaners cannot be used, and fully cured resin can only be removed mechanically
• Not a substitute for MC-Bauchemie’s fine-crack MC-Injekt PU/epoxy range where the defect is a narrow structural crack rather than bulk ground movement
• Application is limited to +5°C to +40°C subsoil/material temperature in frost-free ground, which constrains scheduling on some winter sites

Selection & best practice

Specifications

Industry use cases

How we position MC-Bauchemie MC-Montan Injekt LE

Within MC-Bauchemie’s own range, MC-Montan Injekt LE sits alongside MC-Montan Injekt LE-S — a lower-expansion sibling tuned specifically for soil stabilisation and slab-lifting where a gentler, more controllable rise is wanted — and the separate MC-Injekt PU/epoxy crack-injection resins used for fine structural cracks rather than bulk ground work; Space Arc scopes the right product against the actual defect (ground movement vs. a crack) rather than defaulting to one resin. Outside the MC-Bauchemie stable, specifiers sometimes shortlist Fosroc’s cementitious Conbextra grout range for baseplate and void filling, but Fosroc does not carry a direct high-expansion PU ground-lifting resin equivalent to MC-Montan Injekt LE in its India catalogue — for deep soil consolidation and structural lifting specifically, this product effectively competes with specialist geotechnical PU-lifting systems rather than with mainstream Fosroc waterproofing lines, so no like-for-like Fosroc swap is listed here.

Related Waterproofing products

View all Waterproofing products →