MC-Bauchemie Nafufill KM 250-IN
MC-Bauchemie’s EN 1504-3 Class R4 structural repair mortar — fibre-reinforced, chloride-proof and rated for full structural reinstatement on bridges, tunnels, dockyards and water-retaining structures.
What is it?
A one-component, fibre-reinforced polymer cement concrete (PCC) repair mortar, factory pre-blended to EN 1504-3 Class R4 — the highest structural repair class in the European repair-mortar standard, intended for load-bearing, statically relevant reinstatement work.
Where is it used?
Bridges, flyovers, tunnels, dockyards and marine/coastal structures, water-retaining structures (STPs, WTPs, reservoirs, dams), and industrial buildings — anywhere corroded or spalled RCC cover concrete needs full structural reinstatement.
Why use it?
Delivers 55 N/mm² compressive strength at 28 days with 0mm measured carbonation depth at 90 days and chloride/de-icing-salt resistance, so the repair patch outperforms the surrounding parent concrete instead of merely matching it.
How is it applied?
Mixed with 15-16% water in a forced-action or slow-speed double mixer (hand mixing not permitted), bonded with Nafufill KMH primer for hand-applied work, then trowelled or wet-sprayed in 10-25mm layers up to 50mm total depth per work step, finished with a wood float or sponge squeegee, and cured 3 days protected from sun and wind.
About MC-Bauchemie Nafufill KM 250-IN
Nafufill KM 250-IN is MC-Bauchemie India’s fibre-reinforced polymer cement concrete (PCC), a factory pre-blended, one-component repair mortar built to EN 1504-3 Class R4 — the top structural tier of Europe’s concrete-repair standard. In plain site terms: it’s a grey powder you add water to (15-16%, roughly 4.5-4.8 litres per 30kg bag), mix in a proper mixer, and place by hand-trowel or wet-spray to rebuild spalled, corroded or physically damaged RCC sections where the repaired concrete has to go back to carrying real structural load — not just look patched over. That R4 rating is the reason Space Arc positions it specifically for bridges, flyovers, tunnels, dockyards and water-retaining structures across our Delhi NCR and pan-India project sites, rather than as a general-purpose patch compound.
What separates it from ordinary site-batched cement mortar repair is that every property on the datasheet is factory-controlled rather than dependent on a mason’s water-cement ratio guess: 55 N/mm² compressive strength at 28 days (already 30 N/mm² inside 48 hours), tensile strength above 1.5 N/mm², and — the number that matters most for corrosion-driven repairs — zero measured carbonation depth after 90 days. It’s rated statically allowable and chloride/de-icing-salt resistant, and MC-Bauchemie explicitly lists it as a compliant anode-embedment mortar under EN 12696 for cathodic protection installations, which tells you the segment this product is really built for: critical infrastructure repair where the specifying engineer needs a documented, standards-referenced material, not the cheapest bag on site. Correct use still depends on getting the basics right — SSD substrate condition, SA2-grade de-rusted reinforcement, the Nafufill KMH bond coat for hand application, and mixer-only batching — all of which Space Arc’s application teams handle as standard on every Nafufill KM 250-IN project.
The technical insight
EN 1504-3 grades concrete repair mortars from R1 to R4 by structural performance, and R4 is the ceiling — the class reserved for mortars meant to carry load, not just cover a defect. Nafufill KM 250-IN sits there because it’s formulated as a polymer cement concrete (PCC), carrying aggregate up to 3mm and polymer modification, rather than a fine polymer-cement mortar (PCM) skim coat. The steel/synthetic fibre reinforcement matters more than it looks on a datasheet: PCC repairs gain strength fast (30 N/mm² inside 48 hours) because that’s what site programmes demand, but fast-curing cementitious systems are also the ones most prone to plastic and early-age shrinkage cracking — the fibres are what keep that rapid strength gain from telegraphing into hairline cracks that would otherwise become the next ingress point for water and chlorides. The 0mm carbonation depth after 90 days is the number worth dwelling on: it means the patch isn’t just filling a void, it’s acting as a second line of defence over the rebar it’s protecting, which is the entire point of a repair in a carbonation- or chloride-driven corrosion case rather than a purely cosmetic one.
Where it is used
- Structural reinstatement of spalled or corrosion-damaged RCC on bridges and flyovers
- Full-depth repair of tunnel linings and portal structures
- Concrete restoration on dockyards, jetties and marine/coastal RCC elements
- Repair of water-retaining structures — STPs, WTPs, reservoirs and dams — ahead of waterproofing
- Column, beam and slab-soffit repair in industrial buildings under structural load
- Overhead and vertical repair by wet-spray in confined or access-restricted sites
- Anode-embedment mortar for EN 12696 cathodic protection installations on critical infrastructure
- Reprofiling of larger-section concrete losses up to 80mm in a single work step
Key advantages
- EN 1504-3 Class R4 — the standard’s highest structural repair class, so it can be specified for genuinely load-bearing RCC elements, not just cosmetic patching
- Fibre reinforcement controls plastic and early-age shrinkage cracking that fast-curing PCC repairs are otherwise prone to
- Fast early strength — 30 N/mm² inside 48 hours — supports quicker reopening or formwork/scaffold-strike times on programme-critical repairs
- Zero measured carbonation depth at 90 days, so the repair patch also shields adjacent reinforcement rather than just filling the void
- Chloride-proof and resistant to de-icing salts, suited to marine, coastal and industrial chemical-exposure conditions
- Dual application route — hand-trowel or wet-spray — from the same bag, useful for overhead/vertical work in access-restricted sites
- Factory pre-blended powder removes the water-cement ratio and dosing inconsistency that plagues site-batched CM repairs
- Statically allowable per DIN 1045-2/EN 206-1, giving structural engineers a documented basis to specify it on load-bearing elements
Limitations & considerations
- Hand mixing is explicitly disallowed by the manufacturer — a forced-action or double-shaft mixer is required on site, which smaller contractors may not always have ready
- Requires a dedicated bond coat (Nafufill KMH) for hand application — an extra product and step, not a standalone one-bag solution
- Narrow build-up per pass — 25mm maximum per work step — so deep spalls need multiple staged layers with wait time between lifts, not a single thick pour
- Application is temperature-restricted to 5-35°C substrate/air temperature, a real constraint during North Indian winter mornings or peak summer slab work
- Long-term performance depends heavily on correct SSD substrate condition and SA2-grade de-rusted reinforcement — shortcuts on prep undermine the rated results
- Premium-priced versus ordinary CM/OPC-based patch mortars, so it’s best reserved for genuinely structural repairs rather than cosmetic touch-ups
Selection & best practice
Confirm the repair genuinely needs R4-class structural mortar before specifying it — for shallow cosmetic patching on non-structural concrete, a lower Nafufill class or ordinary CM is more economical. Where it is needed: cut back to sound concrete with adequate clearance behind exposed rebar, de-rust reinforcement to SA2 blasting grade, and bring the substrate to a genuinely saturated-surface-dry state — not bone dry, not glistening wet — before mixing starts. Batch only in a forced-action or slow double-shaft mixer for a full 5 minutes; never hand-mix or split a bag into part-batches, since that’s exactly where the fibre dispersion and rated strength gains get lost on site. For hand-applied work, don’t skip the Nafufill KMH bond coat, and place the repair mortar while it’s still tacky, not after it has skinned over. Build up in 10-25mm passes rather than one thick lift, respecting the 50mm total/80mm-reprofiling limits, and protect every lift from direct sun and wind through the full 3-day cure. Keep application strictly within the 5-35°C window specified — early-morning or late-evening placement is often the only realistic option during Delhi NCR summers.
Specifications
| Type of Product | Polymer Cement Concrete (PCC), one-component, fibre-reinforced |
| Standard / Class | EN 1504-3, Class R4 |
| Grain Size | 0-3 mm |
| Compressive Strength (ASTM C-109, 50mm cube) | 30 N/mm² @48 hrs / 42 N/mm² @7 days / 55 N/mm² @28 days |
| Tensile Strength | >1.5 N/mm² @28 days |
| Carbonation Depth | 0 mm @90 days |
| Fresh Mortar Density | 2090 kg/m³ |
| Layer Thickness | 10mm min / 25mm max per work step; 50mm max total; up to 80mm for reprofiling |
| Pack Size / Shelf Life | 30 kg sacks; 9 months from manufacture, unopened, protected from rain/sun/heat/frost |
Industry use cases
Infrastructure / Roads
Pier caps, girder soffits and expansion-joint-adjacent RCC on bridges and flyovers where chloride ingress from monsoon runoff or de-icing exposure has corroded the rebar.
Water & Wastewater
Reservoir walls and STP/WTP RCC tanks needing structural reinstatement before a waterproofing lining is applied over the repair.
Industrial / Manufacturing
Column and beam spalling repair in process areas under corrosive or chemical exposure conditions.
Marine / Ports
Jetty decks and berths exposed to XS-class tidal and chloride exposure per the product’s rated exposure classes.
Metro / Tunnels
Tunnel lining reinstatement in confined, overhead conditions using the product’s wet-spray application route.
Frequently asked questions
Is Nafufill KM 250-IN suitable for structural, load-bearing repairs, or only cosmetic patching?
Can I mix Nafufill KM 250-IN by hand on a small site?
What primer or bond coat does it need?
How thick can I apply it in one go?
How does this compare to ordinary cement mortar (CM) patch repair?
What pack size does it come in, and what’s the shelf life?
How we position MC-Bauchemie Nafufill KM 250-IN
Within MC-Bauchemie’s own Nafufill range, KM 250-IN is the top-of-line structural grade: Nafufill LM covers R1-class cosmetic reinstatement, Nafufill KM 220 sits at R2, and Nafufill KM 230 at R3, with KM 250-IN reserved for the R4, statically-allowable repairs where the patch has to carry real load. It’s always specified alongside Nafufill KMH as its hand-application bond coat, and for corrosion-driven repairs Space Arc typically pairs it with MC-Bauchemie’s rebar corrosion-protection primers rather than leaving de-rusted steel unprotected under the new mortar. Where a project is already standardised on Fosroc systems, or needs a single-pass depth greater than KM 250-IN’s 25mm-per-step limit, Fosroc’s Renderoc HB40 is the genuine cross-brand equivalent — a comparable R4-class, fibre-reinforced PCC repair mortar rated for up to 40mm in one application. Space Arc stocks and applies both families, so the choice usually comes down to project specification history and single-pass depth requirements rather than any real performance gap between the two.
Fosroc Renderoc HB40 — Specifiers already standardised on Fosroc systems, or needing a single-pass build beyond Nafufill KM 250-IN’s 25mm-per-step limit (Renderoc HB40 is rated up to 40mm in one application), often choose it as the equivalent R4-class alternative.
Related Concrete Repair products
Source MC-Bauchemie Nafufill KM 250-IN for your project
Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.