MC-Dur 1225
Epoxy Bonding Primer and Interface Coat for Concrete Repair and Flooring Systems
Authorized Project Distributor — MC-Bauchemie India | Space Arc Engineering, Ghaziabad
Product Overview
MC-Dur 1225 is a two-component (resin plus hardener) solvent-free low-viscosity epoxy bonding primer manufactured by MC-Bauchemie for application as an interface coat between a prepared concrete substrate and the repair mortar, screed, or coating system applied over it. The product serves a critical function in concrete repair and flooring systems: the bond strength between the repair material and the concrete substrate is the single most important factor determining whether a concrete repair or floor topping remains in service for its intended life or delaminates prematurely as a result of differential thermal movement, loading, or moisture cycling. Standard practice in European EN 1504-part concrete repair systems requires the application of a bonding coat to the prepared concrete surface before applying structural repair mortars (such as MC-Bauchemie MC-RocTec 222 or MC-PowerFlow) when the substrate is porous, dusty, or has been prepared by scarification or grit blasting, to seal the surface, prevent substrate water absorption from the repair mortar (which would reduce the effective water-cement ratio in the interface zone and weaken the bond), and provide a chemically reactive surface for adhesion of the repair material. MC-Dur 1225 achieves this through its low-viscosity epoxy formulation: the mixed primer penetrates into the open pores and capillaries of the prepared concrete surface by surface tension, providing a thin, intimate bond layer between the concrete and the applied repair mortar or coating. When used under cementitious repair mortars, the mortar must be applied while the epoxy primer is still in the tacky (green) stage — the surface must not be dry or cured as the epoxy will act as a bond-breaker. When used under epoxy or polyurethane floor coatings and self-levelling toppings, MC-Dur 1225 also provides a moisture-control function, reducing the risk of moisture blister formation caused by substrate moisture vapour pressure. Space Arc Engineering supplies MC-Dur 1225 for concrete repair contractors, industrial flooring applicators, and waterproofing specialists across Delhi NCR, Ghaziabad, Noida, and Uttar Pradesh.
Applications
- Bonding primer under MC-RocTec 222 and MC-PowerFlow structural repair mortars — EN 1504 repair systems
- Interface coat under MC-Floor 13 cementitious floor topping on prepared concrete substrates
- Primer under epoxy self-levelling floor coatings and epoxy screed systems on concrete floors
- Penetrating primer for porous, dusty, and laitance-free concrete surfaces before coating
- Moisture-control primer under epoxy floor coatings on concrete slabs with residual construction moisture
- Bonding agent between old concrete and new repair sections — bridge deck and infrastructure repair
Key Advantages
- Solvent-free — safe for use in enclosed spaces including basements, tunnels, and underground structures
- Low viscosity — deep penetration into prepared concrete pores for maximum adhesion
- Two-component — factory-proportioned resin and hardener for consistent mix ratio in every application
- Versatile — compatible with MC-Bauchemie cementitious repair mortars and epoxy floor systems
- Reduces moisture blister risk — mitigates the effect of residual substrate moisture under coatings
- EN 1504-compatible — meets the European standard requirement for bonding agents in concrete repair
Technical Data
| Type | Two-component solvent-free low-viscosity epoxy bonding primer and interface coat |
| Mix Ratio | Two-component — refer to current TDS for exact resin to hardener ratio by weight |
| Pot Life after Mixing | Approximately 30 to 45 minutes at 20 degrees C — reduce batch size in Indian summer above 35 degrees C |
| Application Rate | Approximately 0.3 to 0.5 kg per square metre on prepared concrete (surface roughness dependent) |
| Open Time for Mortar Application | Apply cementitious mortar in the tacky stage — approximately 2 to 6 hours after primer application at 20 degrees C |
| Coverage | Approximately 5 to 7 square metres per kg mixed primer depending on substrate porosity |
Get a Quote
+91 9999155255 | info@space-arc.com | Space Arc Engineering, Sahibabad, Ghaziabad
Frequently Asked Questions
Why is a bonding primer like MC-Dur 1225 required in an EN 1504 concrete repair system, and what are the consequences of skipping the primer coat when applying a structural repair mortar like MC-RocTec 222?
The role of the bonding primer in an EN 1504 concrete repair system is frequently misunderstood or omitted by contractors seeking to reduce cost and programme time — with consequences that typically result in the premature delamination of the repair mortar and the need for complete reinstatement at far greater cost than the primer saving. Understanding why the primer is essential requires understanding what happens at the interface between a prepared concrete substrate and a freshly applied cementitious repair mortar. When a structural repair mortar such as MC-RocTec 222 is mixed with water and applied directly to a prepared, dust-free, but unprimed concrete surface, two competing processes occur at the interface. First, if the concrete substrate is porous and partially dry (which it almost always is in Indian site conditions, even when pre-wetted to SSD), the concrete will absorb water from the freshly mixed repair mortar through capillary suction. This water absorption is rapid — it can draw sufficient water from the mortar in the first few minutes after application to raise the effective water-cement ratio of the interface zone of the mortar (the 1 to 2 mm nearest the substrate) significantly above the bulk mix. A higher water-cement ratio produces a weaker, more porous interface zone — sometimes called the transition zone or interfacial zone. This weak zone is where delamination initiates. Second, the drying concrete surface may also have residual dust particles (even after compressed-air cleaning) that coat the aggregate surfaces and prevent direct cement-aggregate bonding at the interface. The epoxy bonding primer addresses both problems simultaneously. The low-viscosity mixed epoxy (MC-Dur 1225) penetrates the open pores of the prepared concrete surface by capillary action, sealing the surface pores and eliminating the capillary suction that would otherwise pull water from the mortar. This ensures that the repair mortar cures with its designed water-cement ratio throughout its full thickness, not just in the bulk but also at the critical interface zone. The epoxy also coats the concrete surface and any residual dust particles, providing a clean, chemically reactive surface to which the cementitious mortar paste can bond through both mechanical interlocking (with the surface texture of the prepared concrete) and chemical adhesion (between the cement hydration products and the epoxy surface). When the repair mortar is applied while the epoxy primer is still in the tacky stage — the surface feels slightly sticky but does not transfer to a gloved finger — the mortar paste physically bonds into the partially cured epoxy surface, creating an intimate, void-free interface. Skipping the primer under a repair mortar has two documented consequences in field practice in India. The first is immediate delamination at the interface — the repair mortar sounds hollow when tapped with a hammer (a drum sound indicating loss of contact) within days to weeks of application. This hollow-sounding repair has essentially no pull-off bond strength and will fall away under load or impact. The second consequence is delayed delamination — the repair mortar appears well-bonded initially but debonds over the first wet season as moisture cycling causes differential thermal and moisture movement at the interface zone. Neither outcome is acceptable in a structural repair where the load-bearing function of the repaired member depends on full composite action between the repair mortar and the existing concrete. The modest cost of MC-Dur 1225 primer (approximately 0.3 to 0.5 kg per square metre at a cost of a few hundred rupees per square metre) is negligible compared to the cost of a failed repair — mobilisation, break-out, repreparation, and reapplication of mortar. For all structural concrete repair works in Delhi NCR and Uttar Pradesh, Space Arc Engineering recommends the complete MC-Bauchemie EN 1504 repair system: preparation, corrosion inhibitor, bonding primer, structural repair mortar, and surface protection — as a single integrated system with a documented performance record.
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Space Arc Engineering is an Authorized Project Distributor for MC-Bauchemie India serving Delhi NCR, Ghaziabad, Noida and Uttar Pradesh.
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