About Fosroc Conbextra EP65

Fosroc Conbextra EP65 belongs to the Conbextra family of precision grouts and sits at the heavy-duty, epoxy end of that range. Where the cementitious Conbextra grouts (GP, GP2, HF) handle routine non-shrink grouting, the EP-series exists for situations a cement grout cannot survive: severe dynamic loading, vibration, repeated impact, and exposure to oils, fats and aggressive chemicals. EP65 is specifically the variant calibrated for thicker pours — gaps in the region of 35 to 65 mm — which is the band typically encountered under larger machine base plates and rail soleplates.\n\nThe product is supplied as a factory-proportioned system: a base epoxy resin, a liquid hardener, and a separately bagged, specially graded inert filler/aggregate. This three-part packaging is deliberate. Whole-pack site mixing in the correct ratio removes the single biggest source of failure in epoxy grouting — incorrect on-site batching — and guarantees the resin-to-filler proportions that give EP65 its strength and low-creep behaviour. Once mixed, the grout is highly fluid and self-levelling, which lets it travel under a base plate and fill the gap without honeycombing, provided a hydrostatic head is maintained through a hopper.\n\nIt is worth being precise about naming, because Indian sites encounter both labels. In several Fosroc markets the original Conbextra EP65 has been superseded by Conbextra EP65 Plus, an upgraded ultra-high-strength two-component epoxy grout that broadens the placeable gap to roughly 10–100 mm and reaches around 125 MPa compressive strength. The two are functionally interchangeable in specification intent — precision epoxy grouting for heavy, dynamic, chemically exposed plant — and our technical team will confirm which designation and pack format is current for your project at the time of supply. Space Arc Engineering, as an authorised Fosroc distributor and applicator across Delhi NCR and Pan-India, supplies the correct current variant together with the matching Nitozinc/Nitomortar surface-preparation and Conbextra companion products where a full grouting system is required.

The technical insight

The engineering value of EP65 lies in how it transfers load, not just in headline strength. For a machine to run true, the grout must keep intimate, full-area contact with the underside of the base plate — what Fosroc calls the effective bearing area (EBA). Cementitious grouts can lose EBA through plastic settlement and drying shrinkage; EP65, being a filled epoxy, is essentially non-shrink and cures with negligible volume change, so it holds EBA close to 100%. Its filler-loaded formulation also gives it low creep under sustained compressive load, meaning the alignment achieved at commissioning does not drift over months of operation. Because epoxy is far stiffer and stronger in tension and flexure than cement, EP65 resists the cyclic and reversing stresses from reciprocating machinery and rail traffic that would fatigue and crack a brittle cementitious bed. The flip side of a thick, filler-rich epoxy is exotherm: in deep single pours the curing reaction generates heat, which is why the EP-series is engineered as a relatively low-exotherm system and why pour depth, ambient temperature and pour staging must be respected. Thermal expansion of epoxy grout is also higher than that of steel or concrete, so EP65 is formulated and filled to keep its coefficient compatible with the structure across the service-temperature window.

Where it is used

• Precision grouting beneath heavy machine base plates and skid-mounted equipment
• Bedding of crane rails, gantry rails and transporter rail soleplates
• Grouting of turbines, centrifuges, compressors and high-speed rotating plant
• Foundations for reciprocating machinery — engines, pumps, drop forges and presses
• Grouting in electroplating shops, chemical plants and areas of chemical/oil spillage
• Anchoring of holding-down bolts, dowels and steel starter bars into pockets
• Repair and re-grouting of failed cementitious beds under vibrating equipment
• Heavy-duty structural grouting where gap widths fall in the 35–65 mm range

Key advantages

• High compressive, tensile and flexural strength — substantially above cementitious grouts
• Non-shrink cure that maintains a high effective bearing area for true load transfer
• Low creep under sustained and dynamic loading, preserving machine alignment over time
• Excellent resistance to repetitive dynamic loads, vibration and impact
• Withstands oils, greases, fats, fresh and sea water, and dilute acids and alkalis
• Free-flowing, self-levelling consistency fills thick gaps without honeycombing
• Solvent-free and factory pre-proportioned for reliable whole-pack site mixing
• Engineered as a low-exotherm epoxy, suited to the deeper 35–65 mm pours

Limitations & considerations

• Markedly higher material cost than cementitious Conbextra grouts — reserve it for genuinely demanding duty
• Designed for a defined gap band (≈35–65 mm); thinner gaps suit EP10/EP40 and very thick or wide pours need staging or EP65 Plus / EPGP
• Limited pot life once mixed (order of tens of minutes); mix only what can be poured continuously and plan batch timing
• Deep single pours generate exotherm — pour depth, ambient temperature and staging must be controlled
• Higher thermal-expansion coefficient than steel/concrete; not ideal where large, rapid temperature swings act on big plan areas
• Requires thoroughly clean, dry, oil-free, grit/shot-blasted substrates — bond is compromised by laitance, grease or standing water
• Leak-proof formwork and a feeding hopper are essential; a free-flow grout will escape and under-fill if forms are not sealed
• Cure rate and flow are temperature-sensitive — low temperatures slow strength gain, high temperatures shorten working time

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Conbextra EP65

Within the Fosroc Conbextra range, EP65 is the heavy-duty epoxy option for thicker 35–65 mm pours — a step up from the cementitious GP, GP2 and HF grouts and a sibling to EP10/EP40 (thin gaps), EP75 (10–75 mm) and the upgraded EP65 Plus / EPGP (10–100 mm), with EP65 Plus formally superseding the older EP40 and EP65 in several markets. Specifiers comparing brands will weigh it against credible epoxy precision grouts such as Sika’s Sikadur-42 / SikaGrout epoxy grouting systems, MYK Schomburg / MBS epoxy grouts, Dr. Fixit (Pidilite) Roff and Fixit grout-and-anchor products, and STP (Shalimar Tar Products) epoxy grouts — most major chemical houses field an equivalent in this class. The honest position is that for routine, lightly loaded non-shrink grouting a cementitious Conbextra grout is more economical and entirely adequate; EP65 earns its premium specifically where dynamic load, vibration, impact or chemical spillage are present and a cement bed would crack or degrade. As an authorised Fosroc distributor and applicator in Delhi NCR and Pan-India, Space Arc Engineering supplies the correct current EP65 variant, pairs it with the right Fosroc surface-preparation and companion products, and provides TDS-based guidance and applicator support so the grout is specified and placed for the actual service condition rather than over- or under-specified.

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