MC-Contact

Polymer-Modified Cementitious Bonding Primer and Slurry for Concrete Repair — Bonding Bridge Between Prepared Substrate and Repair Mortar in EN 1504-Compliant Structural Repair

Authorized Project Distributor — MC-Bauchemie India | Space Arc Engineering, Ghaziabad

Product Overview

MC-Contact is a two-component polymer-modified cementitious bonding slurry from MC-Bauchemie functioning as the bonding primer coat in the complete MC-Bauchemie structural concrete repair system — the intermediate layer between the prepared concrete substrate (and MC-Dur 900 rebar coating) and the structural repair mortar (MC-Dur 200, MC-Dur 300, MC-Dur 400, MC-RocTec SP, or MC-RocTec 45). The bonding coat function — often called the bonding bridge, bonding slurry, or bonding primer in structural repair specifications — addresses a fundamental adhesion challenge in concrete repair: the prepared concrete substrate, after high-pressure water jetting, mechanical scabbling, or grit blasting, presents a highly porous, irregular surface that will absorb water from the repair mortar if applied dry, causing premature drying and shrinkage cracking at the mortar-substrate interface; conversely, if the substrate is excessively wet, the water dilutes the cement paste at the interface, creating a weak interfacial layer between the repair mortar and the substrate. MC-Contact, applied as a brushed slurry in a wet-on-wet technique (the repair mortar is applied into the fresh, undried MC-Contact slurry before it sets), provides: a cement-polymer matrix that penetrates the substrate surface pores and chemically bonds to the substrate; a workable slurry surface for the repair mortar to embed into, creating mechanical interlocking and chemical bonding simultaneously; a layer that prevents premature drying at the interface by maintaining a moist, workable bonding zone during the early period of repair mortar application; and a surface that is more compatible with the repair mortar chemistry than the aged, carbonated concrete substrate surface alone. Space Arc Engineering supplies MC-Contact as part of the complete MC-Bauchemie structural repair system for structural repair contractors, civil maintenance engineers, and infrastructure asset managers in Ghaziabad, Delhi NCR, Noida, and Uttar Pradesh.

Applications

Bonding coat in all MC-Bauchemie structural repair sequences — MC-Contact is applied as the standard bonding coat step between substrate preparation (water jetting, scabbling) plus rebar treatment (MC-Dur 900) and the structural repair mortar (MC-Dur 200, 300, 400, MC-RocTec SP, MC-RocTec 45) in all EN 1504-compliant structural concrete repair projects — beam soffit repair, column face repair, slab soffit repair, retaining wall repair, and bridge structure repair
Bonding primer for concrete patch repair in buildings — application of MC-Contact before patching of impact damage, anchor pull-out repair, spalled cover concrete, and localised honeycombing in reinforced concrete beams, columns, slabs, walls, and foundations in residential, commercial, and industrial buildings undergoing structural repair in Delhi NCR, Ghaziabad, and Uttar Pradesh
Bridge structure concrete repair bonding coat — application of MC-Contact in structural repair of bridge deck slabs, fascia beams, parapet walls, pier caps, and abutment faces in highway bridge maintenance by NHAI and state PWD contractors — the bonding coat is the step most commonly omitted in field repair operations, and its omission is a leading cause of repair mortar delamination within 1 to 3 years of repair completion on bridge structures
Precast concrete repair bonding primer — bonding coat for surface defect repair of precast concrete elements at the precast factory or on site — the bonding coat ensures that repair mortars applied to precast concrete achieve the EN 1542 adhesion requirement across the full repair area and that demoulding, transport, and installation vibrations do not cause premature delamination of the repair from the precast element surface
Bonding coat for screed and floor topping on existing concrete — application of MC-Contact as a bonding primer before application of new floor screed, levelling mortar, or MC-Dur structural repair mortar layers to existing concrete floor slabs where the existing floor surface has been mechanically prepared (shot blasted or scarified) and the new screed or topping must bond monolithically to the existing slab

Key Advantages

Maximises repair mortar adhesion to substrate — the wet-on-wet application technique (repair mortar applied into fresh, unfired MC-Contact slurry) creates a mechanical and chemical interlocking bond at the substrate-mortar interface that routinely exceeds the EN 1542 minimum 1.0 MPa pull-off adhesion requirement — adhesion values of 1.5 to 2.5 MPa are typical for well-applied MC-Contact plus MC-Dur repair mortar combinations, significantly exceeding the tensile strength of the concrete substrate (cohesive failure in pull-off testing indicates bond strength greater than concrete tensile strength)
Controls substrate moisture condition — the brushed slurry application of MC-Contact normalises the moisture condition of the repair area surface: on dry or absorbent substrates, the MC-Contact moisture prevents premature drying at the substrate-mortar interface; on slightly wet substrates, the cement in the MC-Contact bridges the interface in the presence of surface moisture without the dilution effect of applying repair mortar directly to a wet substrate — providing a robust, site-condition-tolerant bonding system
Compatible across the full MC-Bauchemie repair mortar range — MC-Contact is formulated to be chemically and mechanically compatible with all MC-Bauchemie cementitious structural repair mortars (MC-Dur 200, 300, 400, MC-RocTec SP, MC-RocTec 45) and with the MC-Dur 900 rebar corrosion protection coating — providing a single bonding coat product for the entire MC-Bauchemie repair system range without product-specific primers for each repair mortar type
Simple site application by stiff brush — applied by stiff-bristle brush in a scrubbing motion into the substrate surface — no specialist equipment required; consistent with site application conditions for structural repair where surface area shapes and orientations (vertical walls, overhead soffits, internal corners) make roller or spray application impractical — the brush application ensures MC-Contact is worked fully into surface pores and around rebar in complex repair geometries
Reinforces EN 1504 system compliance — use of MC-Contact as the bonding coat step in the repair sequence provides documentation of EN 1504-10 quality management: the bonding coat step is specified in EN 1504 system repair sequences as a means to achieve the adhesion performance requirement of EN 1504-3, and its documented application as part of a system-qualified repair sequence provides specification confidence for structural engineers, clients, and auditors reviewing the completed repair

Technical Data

Type	Two-component polymer-modified cementitious bonding slurry — Component A: OPC-based powder with fine filler; Component B: polymer dispersion (SBR or acrylic) — mix at specified ratio before application
Application Method	Stiff-bristle brush — scrub firmly into prepared substrate surface and apply to MC-Dur 900 rebar coating surface to achieve complete surface coverage with no bare concrete visible
Application Technique	Wet-on-wet — apply structural repair mortar into the MC-Contact slurry before it dries or films over — timing is critical: the repair mortar must be embedded while the MC-Contact surface is still tacky and wet (typically within 10 to 30 minutes of MC-Contact application at 25 degrees Celsius)
Coverage	Approximately 0.3 to 0.5 kg per square metre for brush application — one generous coat ensuring full surface coverage
Pot Life of Mixed Slurry	30 to 60 minutes at 25 degrees Celsius — mix only the quantity that can be applied and covered with repair mortar within this time
Minimum Substrate Strength	Concrete minimum C20 or equivalent tensile pull-off strength greater than 1.5 MPa at the substrate surface — if substrate pull-off is below 1.5 MPa, MC-Contact adhesion performance is limited by the substrate strength
System Adhesion Achievement	Adhesion of repair mortar system to substrate (MC-Contact plus MC-Dur repair mortar) consistently greater than 1.0 MPa (EN 1542) — typical measured values 1.5 to 2.5 MPa on well-prepared C25 or stronger substrate
Storage	Component A: 12 months in sealed bag, dry storage; Component B: 12 months in sealed container above 5 degrees Celsius — protect Component B from freezing

Get a Quote

+91 9999155255 | info@space-arc.com | Space Arc Engineering, Sahibabad, Ghaziabad

Frequently Asked Questions

A structural repair site supervisor asks: the repair specification for a residential building column repair in Noida requires MC-Contact bonding slurry applied before MC-Dur 300 structural repair mortar — the supervisor has applied MC-Contact by brush and is now waiting for the right time to apply the repair mortar — how long should they wait before applying MC-Dur 300 into the MC-Contact, what does the surface look like at the correct application time, and what happens if the MC-Contact is allowed to dry completely before the repair mortar is placed?

This is one of the most practically important questions in structural concrete repair site supervision — the timing of repair mortar application relative to the bonding coat is the single step most often either misunderstood or neglected, and errors at this step are a leading cause of repair delamination failures within months of completion. Here is a complete guide to the correct timing and the surface appearance indicators. The correct application timing — wet-on-wet technique: the MC-Contact bonding slurry must be in a specific surface condition at the time the repair mortar is applied — the surface should be: tacky and damp to the touch; uniformly covered with no areas of dry, chalky MC-Contact; slightly darkened in colour relative to the surrounding dry concrete (indicating moisture retention); and the surface should leave a slight mark on your fingertip if you press lightly — not transfer material, just a slight impression in the surface. This condition is reached 10 to 30 minutes after brushing on the MC-Contact at 25 degrees Celsius — but this timing varies significantly with temperature and humidity in Indian conditions. At 25 degrees Celsius, 50 percent relative humidity (typical of October to February in Delhi NCR): 15 to 25 minutes is the approximate working window between MC-Contact application and repair mortar placement. At 38 to 42 degrees Celsius, 20 to 30 percent relative humidity (typical of April to June in Delhi NCR): the MC-Contact dries very rapidly — the working window may be as short as 5 to 10 minutes; the scrubbing brush technique for MC-Contact application should be followed immediately by the repair mortar crew placing MC-Dur 300; do not apply MC-Contact to a larger area than can have repair mortar placed within 10 minutes in hot dry conditions — apply MC-Contact to 1 square metre at a time in summer, placing repair mortar immediately. At 30 to 35 degrees Celsius, 60 to 80 percent relative humidity (typical of July to September monsoon season): the higher humidity slows evaporation and extends the working window to 20 to 40 minutes; the surface will remain tacky for longer in monsoon conditions. Visual indicators of the correct application window: correct — the surface has a semi-matte, slightly darkened, tacky appearance with no visible sheen of wet slurry but no dusty, dry appearance either; too early (wet stage) — the slurry surface is still wet and glossy — the repair mortar will dilute the MC-Contact at this stage and reduce bond; too late (dry stage) — the surface appears dusty, chalky, or matte white — the cement has dried and the polymer dispersion has formed a film on the surface — applying repair mortar at this stage bonds to the dried film surface rather than to the concrete substrate through the fresh bonding coat; this is the failure mode that causes delamination. What happens if MC-Contact is allowed to dry completely before repair mortar placement: the dried MC-Contact forms a smooth, low-porosity cement-polymer film on the substrate surface; when the repair mortar is applied over this dry film, the bond is between the repair mortar and the dry MC-Contact film surface — not between the repair mortar and the concrete substrate; the bond strength of repair mortar to a dried MC-Contact film is typically 0.5 to 1.0 MPa in pull-off testing — below the EN 1542 requirement of 1.0 MPa minimum and far below the 1.5 to 2.5 MPa achieved with correct wet-on-wet application; the delamination typically occurs at the MC-Contact-concrete interface (the film peels away from the concrete when the repair mortar is loaded) or cohesively through the dried MC-Contact film; the failure is not visible immediately after repair completion but becomes apparent as cracking and delamination at the repair perimeter during the first monsoon season when moisture penetrates behind the repair mortar edge. Recovery procedure if MC-Contact has dried before repair mortar placement: do not attempt to apply repair mortar over dried MC-Contact — the bond will be inadequate and the repair will fail; scrape or scrub off the dried MC-Contact layer with a stiff wire brush or abrasive pad to re-expose the prepared concrete surface; re-apply MC-Contact and immediately place the repair mortar into the fresh tacky coat within the correct timing window; in hot Indian summer conditions where rapid drying is unavoidable, shade the repair area with a tarpaulin to reduce direct solar radiation and direct a portable fan across the area to reduce the temperature — but avoid pointing the fan directly at the freshly applied MC-Contact as the airflow increases evaporation; in the most extreme conditions (above 40 degrees Celsius concrete surface temperature), wet-mist the concrete surface with a fine water spray immediately before MC-Contact application to cool the surface and extend the working window. Space Arc Engineering supplies MC-Contact and the complete MC-Bauchemie structural repair system for contractors in Ghaziabad, Delhi NCR, Noida, and Uttar Pradesh — contact +91 9999155255 for site-specific technical guidance and product supply.

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Space Arc Engineering is an Authorized Project Distributor for MC-Bauchemie India serving Delhi NCR, Ghaziabad, Noida and Uttar Pradesh.

Get MC-Contact — Polymer-Modified Cementitious Bonding Primer and Slurry for Concrete Repair — Bonding Bridge Between Prepared Substrate and Repair Mortar in EN 1504-Compliant Structural Repair — pricing, TDS & technical help

Space Arc Engineering is an authorized MC-Bauchemie distributor & applicator in Delhi NCR & pan-India. Fast quotes, datasheets and on-site support.

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