MC-Bauchemie MC-Stop
A rapid-setting hydraulic plugging cement from MC-Bauchemie that stops live, pressurised water leaks in concrete and masonry in under two minutes, applied straight against a running flow.
What is it?
A single-component, chloride-free hydraulic cement powder that sets in roughly 60 to 120 seconds when mixed with water, forming a rigid, shrink-compensated plug over an active leak.
Where is it used?
Basements, lift pits, water tanks, tunnels, retaining walls, manholes and any concrete or masonry structure with a live water ingress point.
Why use it?
It arrests running water on the spot without dewatering or diverting the flow first, buying a dry, stable base for permanent waterproofing.
How is it applied?
Chase out a keyed groove at the leak, mix a stiff putty, and hand-press it into the void with firm pressure until it sets hard against the water.
About MC-Bauchemie MC-Stop
MC-Stop is MC-Bauchemie’s answer to a problem every site engineer in Delhi NCR eventually faces: a jet or seep of water pushing through a construction joint, a tie-rod hole, a crack or a honeycombed pocket in concrete, refusing to let any conventional mortar or coating grip. It is a factory-blended hydraulic cement that reacts with the very water it is meant to stop. Gauged with clean water into a stiff paste and pressed into the leak, it flash-sets in about a minute to a minute and two, expanding very slightly as it cures so it wedges itself tight into the opening rather than shrinking away from it. The result is a hard, watertight plug that holds back hydrostatic pressure and stays put.
What makes the product genuinely useful on Indian sites is that it does not ask for ideal conditions. You do not need to dewater the pit, drop the water table or wait for a dry weather window. The material is designed to be worked wet, against a flowing leak, using nothing more than hand pressure and a trowel or gloved thumb. Being chloride-free, it is safe against embedded reinforcement, and because it is cement-based it is fully compatible with the concrete substrate and with the crystalline or membrane waterproofing that follows. Think of MC-Stop as the emergency first responder in a leak-repair sequence, not the final treatment on its own.
The technical insight
The behaviour that matters here is hydraulic set combined with controlled expansion. Ordinary Portland-based mortars set slowly and shrink as they cure, so against a live leak the water simply washes the fresh mix out before it can gain strength, and any plug that does form pulls away from the walls of the opening. MC-Stop is formulated with reactive hydraulic binders that hydrate and stiffen in seconds rather than hours, so the material develops grab strength faster than the flowing water can erode it. As it hardens it undergoes a small, deliberate volumetric expansion instead of shrinkage. That expansion is the whole trick: it drives the setting cement hard against the sides of the chased groove, creating a mechanical interlock and a compressive seal that resists the water pressure trying to push the plug back out. Once cured, the plug behaves like a dense, low-permeability concrete of its own, which is why it can hold back a standing head of water and take an overlaid waterproofing system on top of it.
Where it is used
- Sealing active water leaks at construction and day-work joints in basement and retaining walls
- Plugging weeping tie-rod (shuttering) holes and form-tie penetrations in water-retaining concrete
- Arresting jets and seepage through cracks, honeycombs and blowholes in green or old concrete
- Emergency leak-stopping in lift pits, sump pits and underground car parks
- Stopping ingress in water tanks, reservoirs, STPs and swimming-pool structures before lining
- Sealing water entry around pipe penetrations, sleeves and service ducts through slabs and walls
- Leak control in tunnels, metro cut-and-cover works, culverts and manhole chambers
- Fixing and haunching in a keyed groove ahead of a crystalline or membrane waterproofing overlay
Key advantages
- Sets in roughly 60 to 120 seconds, so it stops running water almost immediately
- Works directly against pressurised, flowing water with no need to dewater first
- Shrink-compensated expansion wedges the plug tight into the opening for a lasting seal
- Single-component, chloride-free powder that only needs clean water on site
- Safe against embedded steel reinforcement, unlike chloride-accelerated products
- Cement-based and fully compatible with the concrete substrate and follow-on waterproofing
- Gains useful early strength quickly, letting subsequent trades proceed without long waits
- Simple hand application with basic tools, no primer or specialist equipment required
Limitations & considerations
- It is a spot leak-arrest product, not a standalone waterproofing system, and must be overlaid with a crystalline slurry, membrane or coating for a durable result
- Very fast set means small batches only, gauged for immediate use, and it cannot be retempered once it starts to stiffen
- Effective only where the leak can be physically chased into a keyed groove and hand-pressed; fine, hairline weeping across a large area is better handled by injection or crystalline treatment
- Not a structural or load-bearing repair mortar for large volume reinstatement
- Working and set times shift noticeably with water temperature and dosage, so cold or hot conditions need a trial batch
- Fresh material is strongly alkaline; skin, eye and respiratory protection are essential during mixing and pressing
Selection & best practice
Start by chasing out the leak point into a keyed or undercut groove, roughly 20 mm wide and 20 mm deep as a minimum, so the plug has a mechanical key rather than a shallow smear to hold on to. Remove all loose, friable and laitance-covered material and let the water continue to run; do not try to dry the substrate. Gauge only as much powder as one person can place before it sets, mixing about three to four parts powder to one part clean water by volume into a stiff, putty-like consistency. Work the ball of material firmly into the groove and hold it under sustained hand or trowel pressure for the full set period, usually thirty to ninety seconds, until you feel it go hard and the flow stops. On a strong jet, plug the highest-pressure point first and work outward. Once all leaks are sealed and the plugs have cured, always follow with a crystalline waterproofing slurry or an appropriate MC-Bauchemie coating over the whole area to convert the emergency repair into a permanent, monolithic waterproof surface. In cold or very hot weather, run a small trial batch first to check the set time before committing to the main work.
Specifications
| Product type | Single-component rapid-setting hydraulic plugging cement (powder) |
| Setting time | Approx. 60 to 120 seconds after gauging (temperature and water dependent) |
| Mixing ratio | Approx. 3 to 4 parts powder to 1 part clean water, by volume |
| Mixed consistency | Stiff, putty-like paste for hand application |
| Chloride content | Chloride-free; safe against embedded reinforcement |
| Volume stability | Shrink-compensated, slight expansion on set |
| Standard | Conforms to EN 1504-3, Class R1 (cementitious repair mortar) |
| Groove preparation | Keyed / undercut chase, minimum approx. 20 mm wide x 20 mm deep |
| Application | Hand-pressed against active, flowing water; no dewatering required |
Industry use cases
Basements & Podiums
Stops live leaks at construction joints, tie-rod holes and cracks in retaining and basement walls before a crystalline or membrane system is applied.
Water & Wastewater
Seals seepage in water tanks, reservoirs, STPs and treatment structures so the tank can be dried down and lined without a persistent weep.
Metro & Tunnels
Arrests water ingress in cut-and-cover works, culverts and tunnel segments where active flow makes conventional patching impossible.
Lift Pits & Sumps
Emergency plugging of jetting leaks in lift pits, sump pits and underground car parks to regain a dry, workable base.
Repair & Rehabilitation
First-response leak arrest during basement retrofits and old-structure waterproofing, ahead of full-area protective treatment.
Frequently asked questions
Is MC-Stop a complete waterproofing solution on its own?
Can it really seal a leak while water is still running?
How fast does it set?
Is it safe to use near steel reinforcement?
What surface preparation does it need?
Where can I buy MC-Stop in Delhi NCR?
How we position MC-Bauchemie MC-Stop
MC-Stop sits at the front of a leak-repair sequence, not at the end of it. Pair it with a crystalline waterproofing slurry or an elastomeric membrane from the MC-Bauchemie range to convert the sealed leak into a permanent, monolithic waterproof surface; where the ingress is through fine, distributed cracks rather than a single chaseable point, MC-Bauchemie’s injection resins are the better route. From our wider catalogue, Fosroc and Dr. Fixit both offer comparable rapid plugging mortars and crystalline systems, so specifiers standardised on those brands can be matched to an equivalent stack. Talk to Space Arc if you want the full active-leak-to-permanent-waterproofing system specified as one package rather than a single tin.
Fosroc Renderoc Plug — Choose the Fosroc option when the project is already standardised on a Fosroc waterproofing stack or the consultant specifies BS-referenced products, since Renderoc Plug is a directly equivalent rapid-set plugging mortar for the same active-leak duty.
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