About Fosroc Concrex

Concrex is Fosroc’s answer to the everyday problem of a concrete floor that has started to break up at the surface. Spalls at construction joints, blown-out bug holes on formed faces, potholes on a ramp, chipped kerb edges under constant fork-lift wheels — these are the failures that a cementitious patch struggles to hold because the repair is thin, the loads are point-concentrated and the traffic never really stops. Being an epoxy compound rather than a cement mortar, Concrex sidesteps that weakness: it develops very high compressive and bond strength, has no shrinkage to speak of once cured, and shrugs off the oils, greases and spilt chemicals that soak into and soften ordinary flooring repairs.

For contractors and plant engineers in India the practical draw is speed and durability in one material. A defect can be cut out, cleaned, primed and filled, and the area handed back to fork-lift or light vehicular traffic within roughly 8 to 24 hours depending on temperature — a genuine advantage on a working floor where every hour of shutdown costs money. Space Arc Engineering supplies Concrex as an authorised Fosroc distributor and, where required, carries out the surface preparation and application itself, so the repair is done to the way the product actually wants to be used rather than left to guesswork on site.

The technical insight

The performance comes from the cured epoxy polymer rather than from hydrated cement. When the resin base and hardener are combined in the correct ratio, they cross-link into a dense, closed thermoset matrix that carries load far better than a Portland-cement paste and, critically, does not rely on water for its strength gain — so there is no drying shrinkage and no plastic cracking to open the bond line. That same cross-linked structure is chemically inert, which is why fuels, mineral oils and dilute acids or alkalis wet the surface but do not degrade it. Adhesion is the other half of the story: epoxy wets out a clean, mechanically roughened, dry concrete face and grips into the exposed aggregate, so a properly prepared repair fails cohesively through the concrete before it will ever peel at the interface. The trade-off built into the chemistry is exothermic cure and limited heat tolerance in a single pour — which is why deep repairs are built up in controlled lifts rather than cast in one thick mass.

Where it is used

• Repairing spalls, holes and honeycombing in industrial concrete floors and slabs
• Making good bug holes, voids and pitting on formed and precast concrete faces
• Reinstating spalled edges and potholes on bridge decks and hardstandings
• Rebuilding chipped steps, ramps and kerb edges in high-traffic areas
• Repairing construction- and expansion-joint arrises that carry fork-lift wheels
• Patching localised damage on floors exposed to oils, fuels and dilute chemicals
• Surface reinstatement on loading docks and heavy-duty warehouse aisles
• Filling anchor pockets and small blockouts where high early strength is needed

Key advantages

• Cures stronger in compression than the surrounding concrete, so the patch outlasts the slab
• Bonds so well to prepared concrete that failure occurs in the substrate, not at the repair
• Rapid return to service — trafficable in roughly 8 to 24 hours depending on temperature
• Solvent-free, so it is low-odour and suited to enclosed and occupied buildings
• Resists oils, fuels and dilute acids and alkalis that attack cementitious repairs
• Essentially no shrinkage on cure, avoiding the fine cracking seen with thin cement patches
• Two-part pre-proportioned system that mixes and trowels with standard site tools
• Available in paste and mortar consistencies to suit shallow defects or fuller reinstatement

Limitations & considerations

• Will not bond to a damp or wet substrate — the concrete must be surface-dry before priming
• Oil or grease contamination must be fully removed first or adhesion is lost
• Single-lift depth is limited (typically around 30-40 mm at normal ambient); deeper repairs need multiple layers
• Cure rate and pot life are strongly temperature-dependent, shortening sharply in hot Indian conditions
• As a rigid epoxy it is not intended for moving cracks or joints that need a flexible sealant
• Higher material cost than cementitious mortars, so it is best reserved for defects that justify epoxy performance

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Concrex

Concrex is the go-to when a defect is shallow, load-bearing and needs epoxy strength and chemical resistance. For larger structural patch repairs on floors, tanks and marine structures, Fosroc’s own three-component epoxy mortar Nitomortar S is the heavier-duty sibling in the same family. Where the defect is deep and reinforced and better suited to a cementitious pour, look at Fosroc Renderoc RG microconcrete instead. If the real requirement is sealing a moving crack or joint rather than rebuilding concrete, an epoxy mortar is the wrong tool — a polyurethane or polysulphide joint sealant is the right one, and we can advise from our wider Fosroc, Sika and Dr. Fixit ranges. Space Arc carries all three product families, so the specification can follow the defect rather than the shelf.

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