MC-Bauchemie MC-RocTec 30
A polymer-modified, single-component cementitious repair mortar for structural reinstatement of reinforced concrete in the 15 to 40 mm build range, engineered to the EN 1504-3 Class R3 performance level.
What is it?
A single-component, polymer-modified cementitious repair mortar from MC-Bauchemie, gauged only with clean water on site and placed to an EN 1504-3 Class R3 structural performance level.
Where is it used?
Patch repair and section reinstatement of reinforced concrete beams, columns, slab soffits, bridge decks, pier caps and industrial floors where cover has spalled or delaminated.
Why use it?
Polymer modification gives it strong adhesion to the parent concrete, low drying shrinkage and better resistance to chloride and carbonation ingress than a plain sand-cement mix.
How is it applied?
Applied by trowel or wet-spray onto a saturated, mechanically prepared substrate in 15 to 30 mm lifts, over a bonding coat and, where steel is exposed, an anti-corrosion primer.
About MC-Bauchemie MC-RocTec 30
MC-RocTec 30 belongs to MC-Bauchemie’s family of EN 1504-3 concrete-replacement mortars. It arrives as a factory-blended dry powder that combines Portland cement, graded siliceous aggregate and a redispersible polymer, so the applicator only adds a controlled quantity of clean water to produce a cohesive, thixotropic mortar. That factory blending is the point: batch-to-batch consistency is far tighter than a site-gauged mix, and the polymer content does the heavy lifting on bond and durability. The material is designed for hand and machine placement in reinforced concrete rehabilitation, typically where carbonation or chloride-driven corrosion has caused the cover concrete to crack, delaminate or spall.
In practice it sits in the middle of a repair system rather than working alone. On Indian rehabilitation projects it is used to rebuild lost section on beam soffits, column faces, slab undersides, bridge pier caps and industrial floor edges, generally in a build of 15 to 40 mm per repair zone. Where reinforcement is exposed, the bars are cleaned and given an anti-corrosion coat first; a bonding bridge is then applied to the prepared concrete, and the mortar is packed on while that coat is still tacky. Used this way it forms a monolithic, low-permeability patch that restores both the geometry and the protective cover the structure needs to survive the rest of its design life.
The technical insight
The behaviour that matters in a repair mortar is not headline strength but how well the patch stays bonded and how little it moves as it cures. MC-RocTec 30 addresses both through its polymer film. As the mortar hydrates, the redispersible polymer coalesces into a continuous film that bridges the cement matrix and the aggregate, and keys mechanically into the roughened, pre-saturated substrate. This film raises tensile adhesion so that a correctly prepared repair fails in the parent concrete rather than at the interface, and it toughens the matrix so shrinkage micro-cracking is reduced. The same polymer, together with the dense cement paste, closes the capillary pore network, which is what slows the re-entry of chlorides and carbon dioxide that caused the original corrosion. Because EN 1504-3 Class R3 also caps the mortar’s elastic modulus relative to a rigid R4 grade, the patch flexes broadly in sympathy with the surrounding concrete under load and thermal movement, so stress does not concentrate at the bond line. Correct saturated surface-dry conditioning of the substrate is critical to all of this: a thirsty, dry substrate pulls mixing water out of the fresh mortar, starving hydration at the interface and undermining the very bond the polymer is there to create.
Where it is used
- Reinstating spalled or delaminated cover on reinforced concrete beams and slab soffits
- Rebuilding lost section on columns and pier faces after corrosion-driven damage
- Bridge deck soffit, crosshead and pier-cap repairs under IRC and MORTH-type maintenance
- Patch repair of industrial and warehouse floors at edges, joints and localised breakouts
- Reprofiling honeycombed or poorly compacted concrete revealed after formwork strike
- Making good breakouts around exposed, cleaned and primed reinforcement
- Repairs to water-retaining and marine-exposed structures needing low-permeability cover
- Localised structural patching ahead of a protective anti-carbonation or surface coating
Key advantages
- Single component – only clean water is added on site, reducing dosing error
- Polymer modification delivers high adhesion, so a sound repair fails in the parent concrete
- Builds 15 to 40 mm in the repair zone, cutting the number of lifts on deeper breakouts
- Low drying shrinkage limits interface cracking and debonding as the patch cures
- Dense, low-permeability matrix resists chloride and carbonation re-ingress
- Placeable by trowel or wet-spray, suiting both small patches and larger elevations
- Formulated to EN 1504-3 Class R3, giving specifiers a recognised compliance reference
- Part of a complete MC-Bauchemie system with matching bond coat and rebar primer
Limitations & considerations
- It is a structural repair mortar, not a free-flowing micro-concrete – deep, formed or congested pours need a pourable grade instead
- Placement per lift is limited; very deep breakouts must be built up in successive layers with the correct waiting time
- Performance depends heavily on substrate preparation and saturated surface-dry conditioning – a dry or dusty substrate will compromise bond
- Not a standalone waterproofing product; structures under hydrostatic pressure still need a dedicated waterproofing system
- Application and curing outside the recommended 5 to 30 degrees C window, or without protection from wind and sun, risks plastic and drying cracking
- Exact set times, layer limits, yield and pack size vary by production batch and revision – always work to the current product data sheet supplied with the material
Selection & best practice
Break out all loose, carbonated or chloride-contaminated concrete back to a sound, roughened substrate and cut a defined square edge – never feather the repair to nothing. Expose corroded reinforcement fully around its circumference, grit or wire-brush it to bright metal, and apply the anti-corrosion coat before proceeding. Pre-soak the concrete so it reaches a saturated surface-dry condition with no standing water, apply the bonding coat, and place the mortar wet-on-tacky, compacting it firmly against the substrate and around the bars. Build up deep repairs in lifts within the stated per-layer limit rather than in one heavy pass. Gauge strictly with the specified water quantity – excess water is the most common cause of shrinkage cracking and low strength. Finish, then cure continuously for the recommended period using wet hessian, a curing membrane or fine mist, protecting the fresh repair from direct sun, drying wind and rain until it has gained strength.
Specifications
| Product type | Single-component, polymer-modified cementitious repair mortar |
| Base | Portland cement, graded siliceous aggregate and redispersible polymer |
| Standard / class | EN 1504-3 Class R3 (structural repair) |
| Compressive strength (R3 class requirement) | >= 25 MPa at 28 days per EN 1504-3 |
| Application build | Approx. 15 to 40 mm in the repair zone, placed in lifts |
| Mixing | Add clean water only, to the ratio stated on the current data sheet |
| Application method | Hand (trowel) or wet-spray onto a bonding coat |
| Substrate condition | Saturated surface-dry, mechanically prepared, no standing water |
| Curing | Continuous moist curing (wet hessian / membrane) after finishing |
Industry use cases
Bridges & Highways
Reinstating spalled cover on deck soffits, crossheads and pier caps during IRC and MORTH-type structural maintenance of RC and PSC bridges.
Commercial & Residential Buildings
Repairing corrosion-damaged beams, columns and slab soffits in ageing RCC structures ahead of an anti-carbonation protective coating.
Industrial Plants & Warehouses
Patching breakouts, honeycombing and floor-edge damage where cover has been lost to mechanical or chemical wear.
Water & Marine Structures
Rebuilding low-permeability cover on tanks, channels and coastal structures exposed to moisture and chloride attack.
Car Parks & Infrastructure
Localised structural patch repair of decks and columns in multi-storey car parks affected by de-icing salts and carbonation.
Frequently asked questions
What EN 1504 class does MC-RocTec 30 meet?
How thick can I apply it in one go?
Do I need a bonding coat and a rebar primer?
Is MC-RocTec 30 waterproof?
Can it be sprayed?
How is MC-RocTec 30 different from a pourable micro-concrete?
How we position MC-Bauchemie MC-RocTec 30
Position MC-RocTec 30 as the go-to hand- or spray-applied structural repair mortar for 15-40 mm reinstatement within the MC-Bauchemie EN 1504 concrete-repair system. It works alongside a Zentrifix KMH-type anti-corrosion and bond coat on the reinforcement and substrate, and specifiers who need a different strength band can move within MC-Bauchemie’s Nafufill replacement-mortar range – a lighter R2/R3 fine mortar for shallow reprofiling or an R4 grade such as Nafufill KM 250 for heavy structural section loss. Where a free-flowing, formed pour is required rather than a trowelled patch, cross-refer to a pourable micro-concrete. Across our other brands, the closest equivalents we stock are Fosroc’s Renderoc range and Sika’s MonoTop repair mortars, so we can match whichever system a consultant has already specified. Always confirm the exact SKU and current technical data sheet against the project specification before ordering.
Fosroc Renderoc GP — Choose the Fosroc Renderoc GP when the project specification is already written around the Fosroc repair system, or when you need a general-purpose hand-applied R3 mortar for vertical and overhead patch repair from a single Fosroc supply chain.
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