MC-Bauchemie MC-Nafufill SB
A machine-sprayed, fine-aggregate cementitious mortar that repairs and reprofiles concrete while sealing it against carbonation in a single high-output operation.
What is it?
A factory-blended, polymer-modified cementitious mortar with a 2 mm maximum aggregate, engineered to be pumped and sprayed onto concrete as a thin protective repair render.
Where is it used?
Bridge piers and abutments, tunnel linings, retaining walls, building frames, silos, chimneys and precast panels where large surface areas need repair plus anti-carbonation protection.
Why use it?
It combines structural fine repair (EN 1504-3) with surface protection (EN 1504-2) in one product, so a single spray pass reprofiles the concrete and slows CO2 ingress.
How is it applied?
Site-mixed with clean water and spray-applied through a rotor-stator mortar pump at 5-20 mm per pass onto a saturated, sound substrate, then finished as required.
About MC-Bauchemie MC-Nafufill SB
MC-Nafufill SB is MC-Bauchemie’s answer to a very practical problem on large concrete structures: how to repair and protect big surface areas quickly without compromising on durability. It is a one-pack, polymer-modified cementitious mortar supplied as a dry powder that is mixed with water on site and then pumped through a rotor-stator machine to be sprayed onto the substrate. The fine 2 mm aggregate lets it be laid in thin, even layers of 5 to 20 mm per pass, which is exactly what you want when the goal is a uniform protective skin rather than a bulky patch. Because it is spray-applied, a trained crew can cover 200 to 400 square metres in a working day, which changes the economics of jobs like a full bridge deck soffit or a tunnel wall that would be painfully slow to trowel by hand.
What sets MC-Nafufill SB apart from an ordinary repair mortar is that it is designed to do two jobs at once. It qualifies as a structural fine repair mortar under EN 1504-3 (Class R1 to R2) while also meeting EN 1504-2 for surface protection, thanks to a high carbon-dioxide diffusion resistance. In plain terms, the same material that rebuilds a spalled or weathered surface also acts as an anti-carbonation render, keeping the aggressive CO2 that drives reinforcement corrosion away from the steel. For asset owners in India dealing with ageing flyovers, water-retaining structures and industrial concrete, that dual function means fewer separate coats, fewer interfaces to fail, and a faster route back to service.
The technical insight
The durability logic behind MC-Nafufill SB rests on carbonation control. Ordinary concrete stays passive because its high alkalinity protects the embedded steel; over years, atmospheric CO2 reacts with the cement paste, drops the pH, and once that carbonation front reaches the reinforcement, corrosion begins and the cover cracks and spalls. MC-Nafufill SB attacks this at the surface. Its polymer modification produces a dense, low-permeability matrix with a CO2 diffusion resistance expressed as an sd value greater than 50 metres at just 10 mm dry film thickness. That means a thin sprayed layer behaves, in carbonation terms, like tens of metres of still air, dramatically slowing the ingress front. The fine aggregate and polymer content also give a strong mechanical bite: bond strength above 0.8 MPa by EN 1542 pull-off and 28-day compressive strength above 20 MPa (EN 12190), so the render is monolithic with the parent concrete rather than a loosely adhered skin. The spray application is not just about speed, it is about compaction. Pumping the mortar and projecting it at velocity onto a saturated substrate drives out entrapped air and forces intimate contact into the surface texture, which is what delivers reliable adhesion in the thin 5 to 20 mm sections this product is built for.
Where it is used
- Anti-carbonation repair render on bridge piers, abutments and deck soffits
- Surface restoration of tunnel linings and cut-and-cover structures
- Protective reprofiling of retaining walls and basement retaining structures
- Frame and facade restoration on RCC buildings after refurbishment
- Surface repair of precast concrete panels and architectural elements
- Restoration of concrete chimneys, silos and cooling-tower shells
- Large-area levelling of weathered or eroded concrete surfaces
- Reinstatement of cover to reinforcement over broad, shallow-depth zones
Key advantages
- High-output machine spraying covers 200-400 m2 per day, cutting labour cost on large jobs
- Dual EN 1504-2 and EN 1504-3 compliance means repair and surface protection in one product
- Fine 2 mm aggregate gives thin, uniform layers of 5-20 mm and a smooth finished surface
- High CO2 diffusion resistance (sd greater than 50 m at 10 mm) provides genuine anti-carbonation defence
- Strong pull-off bond above 0.8 MPa ensures the render stays monolithic with the substrate
- Single-component powder simplifies site logistics, storage and quality control
- Well suited to vertical and overhead work where thin, adherent sections are essential
- Consistent factory-blended formulation removes site batching variability
Limitations & considerations
- Requires a rotor-stator mortar pump and trained spray operators, so it is not suited to small hand patches
- Classified R1-R2, so it is not intended for deep structural or high-build load-bearing repairs
- Thin-section spray render depends heavily on correct substrate preparation and saturation to bond well
- Coverage and finish quality vary with pump setup, nozzle and operator technique
- Like all cementitious sprays, overspray, wind and fresh rain during application need managing on exposed sites
- Needs proper curing to develop strength and its full carbonation resistance
Selection & best practice
Success with MC-Nafufill SB is decided before the pump ever starts. Prepare the substrate to a sound, roughened, laitance-free profile, remove any corroded steel scale and treat exposed reinforcement, then pre-saturate the concrete to a saturated-surface-dry condition so the render is not starved of water. Mix only with clean water at the specified ratio, using a forced-action or the mortar-pump mixing arrangement, and run the material through a rotor-stator pump with a stator and nozzle sized for a 2 mm mortar (4 mm or smaller). Spray in even passes of 5 to 20 mm, building up in layers where more thickness is needed and keying between them. Finish to the required texture while the mortar is still workable, protect the fresh surface from direct sun, wind and rain, and cure it properly so the polymer-modified matrix reaches both its rated strength and its anti-carbonation performance. Always work to the current MC-Bauchemie technical data sheet and trial a sample area to dial in the pump on each site.
Specifications
| Product type | Polymer-modified, fine-aggregate cementitious spray mortar (one-component powder) |
| Maximum aggregate size | 2 mm |
| Layer thickness | 5-20 mm per spray pass |
| Compressive strength (28 days) | >20 MPa (EN 12190) |
| Bond strength | >0.8 MPa pull-off (EN 1542) |
| CO2 diffusion resistance | sd value >50 m at 10 mm dry film thickness |
| Standards | EN 1504-2 (surface protection) and EN 1504-3 Class R1-R2 |
| Application method | Rotor-stator mortar pump with 4 mm or smaller stator/nozzle |
| Packaging | 25 kg multi-wall paper bags |
Industry use cases
Bridges and highways
Anti-carbonation render on piers, abutments and deck soffits, restoring cover and slowing CO2 ingress across large, hard-to-access surfaces.
Tunnels and metro
Fast machine-sprayed restoration of tunnel linings and cut-and-cover walls where downtime windows are short and areas are extensive.
Water and industrial structures
Reprofiling and protection of retaining walls, silos, chimneys and cooling towers exposed to weathering and aggressive environments.
Commercial and residential RCC
Frame and facade restoration after refurbishment, giving a uniform protected surface ready for further coatings.
Precast manufacturing
Surface repair and blemish correction on precast panels and architectural elements before dispatch or installation.
Frequently asked questions
Is MC-Nafufill SB a structural repair mortar or a coating?
Can it be applied by hand or does it need a machine?
How does it protect against carbonation?
What thickness can I build in one pass?
What preparation does the concrete need first?
Does Space Arc supply and support application across India?
How we position MC-Bauchemie MC-Nafufill SB
MC-Nafufill SB sits in Space Arc’s concrete repair and rehabilitation range as the high-output, spray-applied option for large anti-carbonation jobs. Within the MC-Bauchemie Nafufill family, pair it with a hand-applied fine leveller such as Nafufill KM 103 or KM 110 for small patches and detailing, step up to a two-component high-performance fine mortar like Nafufill R3 FM (R3) where higher strength is needed, and use Nafufill SBR as an SBR bonding bridge where extra adhesion assurance is specified. Where a project standardises on Fosroc, our Renderoc range offers comparable fine-repair and fairing options; and for the protective coating stage over any of these renders, look at our anti-carbonation and protective coatings lines from Fosroc (Dekguard) and MC-Bauchemie to complete a durable surface-protection system.
Fosroc Renderoc FC — Specify the Fosroc Renderoc FC fairing coat when a project is standardised on Fosroc and needs a thin fine-repair or blemish-blinding coat, though it is a hand-applied fairing coat rather than a high-output machine-sprayed anti-carbonation render like MC-Nafufill SB.
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