Fosroc Conbextra EPR
Three-component epoxy resin free-flow grout for high dynamic loads and chemically aggressive conditions, engineered for precise baseplate and machine-rail bedding from 10 to 120 mm.
What is it?
A three-component, solvent-free epoxy resin free-flow grout (base resin, liquid hardener and graded inert fillers) for filling gaps of 10-120 mm where high strength, low creep and resistance to dynamic loads are required.
Where is it used?
Bedding of machine baseplates, turbine and compressor mounts, crane and transporter rails, forging hammers and other plant subject to heavy, repetitive or vibrating loads, and areas exposed to oil or chemical spillage.
Why use it?
It develops very high early compressive strength (90 MPa at 1 day), is effectively non-shrink, exhibits low creep under sustained load and resists vibration, fatigue and chemical attack far better than cementitious grouts.
How is it applied?
Components are batch-mixed in the supplied proportions, then poured or pumped into the prepared gap from one side to maintain continuous flow, working within the pot life and within the 5-25 degC placement window.
About Fosroc Conbextra EPR
Fosroc Conbextra EPR is a precision epoxy grout built for the most demanding machinery-bedding situations a structural or plant engineer encounters in India. It is a three-component system: a base resin, a liquid hardener and a pre-weighed blend of specially graded inert fillers. On site the three parts are combined to produce a free-flowing, pourable grout that completely fills the annular gap between a steel baseplate, sole plate or rail and its concrete foundation, leaving no voids that could later become stress concentrators.
What separates Conbextra EPR from the cementitious Conbextra family (such as Conbextra GP or Conbextra HF) is the resin matrix. Cement grouts are excellent for general structural infill, but under continuous vibration, repetitive impact or sustained high bearing pressure they can micro-crack and creep. Conbextra EPR’s cured epoxy gives a dense, impervious, high-modulus bedding that holds alignment under exactly those conditions. It is positioned for the 10-120 mm gap band; where the gap is thinner (0.25-10 mm) Fosroc offers Conbextra EP10 as the companion product, and Space Arc Engineering stocks both so the right grade can be matched to the actual measured gap.
The product carries credible third-party classification. It conforms to BS EN 1504-3 as a Class R4 structural repair/grouting product and to BS EN 1504-6 for the anchoring of reinforcing steel bar, and it carries an EN 13501-1 reaction-to-fire classification of C1 s1 d0. For Indian consultants writing specifications, this gives a recognised European benchmark to cite alongside the project’s own IS-based documentation. Because the grout is solvent-free and effectively non-shrink, the cured plug stays in intimate, load-bearing contact with both the steel and the substrate, which is the single most important factor in keeping rotating and reciprocating equipment in alignment over its service life.
Typical buyers are EPC contractors, plant and machinery erectors, structural consultants and procurement teams handling power, cement, steel, petrochemical and heavy-fabrication projects. Space Arc Engineering supplies Conbextra EPR as an authorised Fosroc distributor and applicator across Delhi NCR and Pan-India, with technical support on grade selection, gap measurement and placement method.
The technical insight
The engineering value of Conbextra EPR lies in the combination of very high early strength and a controlled, low-creep epoxy matrix. It reaches roughly 90 MPa compressive strength at one day and about 100 MPa at seven days, with flexural strength near 37 MPa and tensile strength near 14 MPa, so machinery can often be commissioned quickly without sacrificing long-term load capacity. The compressive elastic modulus is about 22 GPa (flexural modulus around 15.5 GPa), giving a stiff bedding that transmits load uniformly into the foundation rather than flexing under each cycle. Pull-off bond strength of around 2.9 MPa secures the grout to a properly prepared substrate. The glass transition temperature is about 56 degC, so the resin retains its mechanical performance through the elevated temperatures common around turbines and heavy plant in Indian conditions. The practical constraint engineers must respect is pot life, which is strongly temperature dependent: roughly 60 minutes at 10 degC, 30 minutes at 20 degC and only about 15 minutes at 30 degC. On a hot Indian site this short working time governs batch size and pour planning, and it is the reason placement is recommended between 5 and 25 degC, with materials conditioned and the pour sequenced from one side to avoid air entrapment.
Where it is used
- Bedding grout under reciprocating and rotating machinery baseplates where dynamic loads are encountered
- Grouting of high-speed turbines, compressors, centrifuges and generator sole plates
- Setting and re-levelling of heavy crane rails, transporter rails and gantry tracks
- Foundations for drop forges, forging hammers and testing/impact equipment
- Grouting in plant areas exposed to oil, fuel or chemical spillage
- Structural gap-filling of 10-120 mm requiring high strength and minimal shrinkage
- Anchoring of reinforcing steel bar in accordance with BS EN 1504-6
Key advantages
- Very high early compressive strength (about 90 MPa at 1 day) allows rapid commissioning
- Effectively non-shrink, giving full, void-free contact between baseplate and foundation
- Excellent resistance to repetitive dynamic, impact and vibrating loads
- Low creep under sustained high bearing pressure, preserving machine alignment
- Free-flowing and pourable, so it fills congested and deep 10-120 mm gaps cleanly
- Good chemical resistance to oils, fuels and many spillages encountered in plant areas
- Dense, impervious cured matrix with high elastic modulus for uniform load transfer
- Classified to BS EN 1504-3 Class R4 and BS EN 1504-6 for specifier confidence
Limitations & considerations
- Short, temperature-sensitive pot life (about 15 minutes at 30 degC) demands disciplined batching on hot sites
- Recommended placement window of 5-25 degC may require shading, chilling of materials or early-morning pours in Indian summers
- Three-component mixing must follow the full supplied proportions; partial or eyeballed batches risk under-cure
- Intended for the 10-120 mm gap band; thinner gaps of 0.25-10 mm need Conbextra EP10 instead
- Higher material cost than cementitious grouts, so best reserved for genuinely dynamic or chemically aggressive duties
- Substrate must be sound, clean and suitably prepared; bond and performance depend on correct surface preparation
- Solvent-free but still a reactive epoxy system requiring appropriate PPE and ventilation during mixing
Selection & best practice
Measure the actual gap before ordering and confirm it falls in the 10-120 mm band, otherwise switch to Conbextra EP10 for thinner sections. Condition all three components and the substrate to keep placement between 5 and 25 degC, and on hot Indian sites work in the early morning or shade the area so the pot life does not collapse. Prepare the concrete to a sound, clean, dry surface and form a leak-tight shutter with a head box on one side. Mix the full base, hardener and filler proportions mechanically until uniform, then pour or pump continuously from one side only so the grout drives air ahead of it and fills the gap without entrapment. Plan batch sizes against the temperature-adjusted pot life and have enough labour ready to place each batch before it stiffens.
Specifications
| Product type | Three-component epoxy resin free-flow grout (base resin + hardener + graded inert fillers) |
| Gap / section thickness | 10 mm to 120 mm (use Conbextra EP10 for 0.25-10 mm) |
| Compressive strength (1 day) | approx. 90 MPa |
| Compressive strength (7 days) | approx. 100 MPa |
| Flexural strength | approx. 37 MPa |
| Tensile strength | approx. 14 MPa |
| Pull-off bond strength | approx. 2.9 MPa |
| Elastic modulus (compression) | approx. 22 GPa |
| Flexural modulus | approx. 15.5 GPa |
| Glass transition temperature | approx. 56 degC |
| Pot life | approx. 60 min @ 10 degC, 30 min @ 20 degC, 15 min @ 30 degC |
| Placement temperature | 5 degC to 25 degC |
| Standards | BS EN 1504-3 Class R4; BS EN 1504-6 (rebar anchoring); EN 13501-1 fire class C1 s1 d0 |
| Pack size | 15 litre pack |
| Shelf life / storage | 18 months in dry conditions at 20 degC in unopened packs |
Industry use cases
Power generation
Bedding of steam and gas turbine, generator and large pump baseplates where high-speed rotation produces continuous vibration and alignment must be held.
Cement & heavy industry
Grouting under crushers, mills, kiln drives and crane rails subject to heavy impact and repetitive loading.
Steel & forging plants
Foundations for drop forges, forging hammers and rolling-mill equipment that impose severe shock and dynamic loads.
Petrochemical & process plants
Machine bedding in areas exposed to oil, fuel and chemical spillage where a dense, chemically resistant grout is needed.
Material handling & ports
Setting and re-levelling of transporter rails, gantry and EOT crane tracks carrying heavy mobile loads.
Frequently asked questions
Is Fosroc Conbextra EPR an epoxy or a cementitious grout?
What gap thickness does Conbextra EPR cover?
What strength does it achieve and how quickly?
Why does pot life matter so much in Indian conditions?
Which standards does Conbextra EPR meet?
Can Space Arc Engineering supply it across India?
How we position Fosroc Conbextra EPR
Conbextra EPR sits at the high-performance, dynamic-load end of Fosroc’s grouting range. Within the Fosroc family it complements the thinner-gap epoxy Conbextra EP10 and contrasts with the cementitious Conbextra GP and high-flow Conbextra HF, which remain the sensible, more economical choice for static structural infill where epoxy performance is not required. Where deeper or fully flowable epoxy duties arise, related grades such as Conbextra EP150 may also be considered. Against competitor products, credible alternatives an Indian specifier might evaluate include Sika’s epoxy grouts (for example SikaGrout-3200 series epoxy grout), MBS (MYK Schomburg) epoxy grouting systems, STP and Dr. Fixit epoxy/precision grouts. Conbextra EPR’s strongest case is when genuine dynamic loading, impact, vibration or chemical spillage is present and the cost premium over cement grout is justified; for routine baseplate filling without those demands, a cementitious Conbextra grade is usually the better-value specification. Space Arc Engineering can help match the duty to the right grade rather than over-specifying.
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Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.