About MC-Bauchemie MC-RocTec 45

MC-RocTec 45 is a single-component, fine-grain repair mortar supplied as a pre-blended dry powder that you simply gauge with clean water on site. It is built on a Portland cement base, carries graded fine silica aggregate with a maximum grain size of roughly 1 to 1.5 mm, and is modified with redispersible polymer powders. That fine grading is the whole point of the product: it lets you close-trowel the surface to a smooth finish that reads like fair-faced formed concrete, rather than the coarser texture you get from a heavy-build mortar. It is intended for shallow repairs in the 5 to 15 mm range per pass, which makes it the right tool for cosmetic-yet-structural reinstatement work where appearance and profile both matter.

For engineers and contractors, the appeal is that MC-RocTec 45 behaves as a structural repair material while still finishing cleanly. It develops a compressive strength greater than 25 MPa and pulls off the substrate at over 1.0 MPa, so it is not a skim coat or a levelling render – it is a load-relevant repair mortar that happens to trowel well. Space Arc Engineering supplies it as an authorised MC-Bauchemie project distributor across Delhi NCR and Pan-India, and our applicators use it on the kind of beam-soffit, column and slab work where a specifier wants the repaired zone to be visually continuous with the surrounding concrete once formwork or scaffold comes down.

The technical insight

The mortar earns its performance from the polymer redispersible powders blended into the cement. When you gauge the powder with water, those polymers re-emulsify and, as the mortar cures, form a continuous polymer film woven through the cement matrix. That film does two useful things at once: it raises adhesion to the prepared substrate, so the repair keys firmly rather than debonding at the interface, and it curbs drying shrinkage, so the patch is far less likely to craze or pull away at its edges. The fine, well-graded silica aggregate keeps the paste-to-aggregate ratio high enough to close-trowel a dense, smooth face, while still limiting the water demand that would otherwise weaken the mix. This is why the 5 mm minimum build matters – feather edges thinner than that cure poorly, lose the benefit of the polymer film, and are the first thing to fail. Keep the mix stiff and honour the depth window, and you get a repair that is both structurally sound and cosmetically clean.

Where it is used

• Beam soffit and web repair in the 5-15 mm depth band
• Shallow-depth reinstatement of column faces
• Surface repair of walls in industrial and infrastructure structures
• Slab soffit repair in multi-storey and parking structures
• Repair and remediation of precast concrete elements
• Making good honeycombing, form-tie holes and shallow blemishes on fair-faced concrete
• Cosmetic-structural patching where the finished surface must match adjacent concrete

Key advantages

• Fine grain trowels to a smooth, fair-faced finish comparable to formed concrete
• Structural-grade compressive strength above 25 MPa (EN 12190)
• Strong bond to prepared substrate, over 1.0 MPa pull-off (EN 1542)
• Polymer modification cuts drying shrinkage and reduces edge cracking
• Applied by hand trowel or by mortar-pump spray to suit site logistics
• Single-component – just add water, no separate liquid polymer to batch
• Complies with EN 1504-3 as a structural repair mortar class
• Builds 5-15 mm in a single pass for efficient shallow repairs

Limitations & considerations

• Shallow-depth material – not suited to deep or full-depth reinstatement beyond 15 mm per pass
• Feather edges thinner than 5 mm cure poorly and should be avoided
• Overhead work above roughly 8 mm needs a two-pass technique to prevent sagging
• Over-watering the mix reduces strength and increases shrinkage, so water dosage must be controlled
• Requires sound, properly prepared and pre-wetted substrate to achieve the stated bond
• Not a substitute for a high-build vertical/overhead mortar where large sections must be rebuilt

Selection & best practice

Specifications

Industry use cases

How we position MC-Bauchemie MC-RocTec 45

MC-RocTec 45 is the fine-finish, shallow-depth member of the concrete-repair toolkit. Reach for it when appearance and profile matter and repair depths sit in the 5-15 mm band. When sections need to be rebuilt deeper, on vertical or overhead faces, step up to MC-Bauchemie’s Nafufill high-build repair grades within the same brand family. It pairs naturally with an MC-Bauchemie bonding primer and a suitable protective or anti-carbonation coating (such as the MC-Color or Emcephob range) to complete a durable repair system. Where a project is specified around Fosroc, our Fosroc Renderoc line offers directly comparable repair mortars, and for surface protection our Dr. Fixit and STP options cover waterproofing that often accompanies structural repair work.

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