Fosroc Nitowrap EP(GF)
Epoxy-bonded glass fibre (GFRP) wrapping system for strengthening and seismic retrofit of RCC and masonry structures.
What is it?
A site-applied glass-fibre-reinforced-polymer (GFRP) wrapping system. The Nitowrap GF glass fabric is bonded to the structure with the Nitowrap 30 epoxy primer and Nitowrap 410 high-build epoxy saturant, with a Nitowrap 512 polyurethane topcoat over exposed structures.
Where is it used?
Externally bonded onto RCC columns, beams and slabs, plus masonry walls, piers, chimneys, tunnels and pipes that need added shear, flexural or confinement capacity, including seismic retrofit work.
Why use it?
It raises the load-carrying, shear and tensile capacity of a member with almost no added dead load or section size, it conforms to any shape, and glass fibre resists acids and alkalis well, so it suits aggressive and coastal environments common across India.
How is it applied?
Prepare and prime the surface with Nitowrap 30, apply Nitowrap 410 saturant, lay and fully wet-out the Nitowrap GF fabric in the design fibre direction, consolidate to remove air, then overcoat with Nitowrap 512 where exposed.
About Fosroc Nitowrap EP(GF)
Fosroc Nitowrap EP(GF) is the glass-fibre member of Fosroc’s Nitowrap structural strengthening family, a range built around externally bonded fibre-reinforced-polymer (FRP) composites. Where conventional repair restores a member to its original state, an FRP wrap adds genuine new structural capacity by bonding high-strength fibres to the outside of a concrete or masonry element. In the EP(GF) system those fibres are E-glass, supplied as the Nitowrap GF woven fabric, which is impregnated on site with cold-cured epoxy resin to form a stiff, load-sharing composite laminate that acts compositely with the parent member.\n\nThe system is not a single tin. It is a defined build-up of four Fosroc products, each with its own job. Nitowrap 30 is a low-viscosity epoxy sealer-cum-primer that penetrates and seals the prepared substrate and creates the bond bridge for the laminate. Nitowrap 410 is a high-build, amber epoxy saturant that both wets out the glass fabric and forms the resin matrix that locks the fibres in place. Nitowrap GF is the engineered glass fabric itself, carried on rolls one metre wide. Finally, where the strengthened element is exposed to weather, daylight or UV, a grey Nitowrap 512 polyurethane topcoat is applied to protect the epoxy matrix, which on its own can chalk and degrade under sunlight.\n\nFor Space Arc Engineering’s clients across Delhi NCR and the rest of India, Nitowrap EP(GF) is most relevant where a structure has to carry more than it was designed for, has lost capacity to corrosion or distress, or has to be brought up to current seismic codes without demolition. Because the wrap is thin and follows the contour of the member, columns keep their dimensions, headroom in beams and slabs is preserved, and disruption to a working building is minimal compared with concrete jacketing or steel plate bonding. Glass fibre is chosen over carbon where the priority is confinement, ductility and economy rather than the very highest stiffness, and where good chemical resistance to acids and alkalis is wanted, for example in industrial, water-retaining and coastal structures.\n\nAs an authorised Fosroc distributor, Space Arc Engineering supplies the complete genuine Nitowrap EP(GF) system, the matching primer, saturant and topcoat, and connects specifiers with method statements and trained applicators so the laminate is built and cured correctly. The design itself, fibre quantity, number of layers and orientation, must always come from a qualified structural engineer working to the project-specific loads.
The technical insight
The strength of a Nitowrap EP(GF) repair lives in two interfaces, not in the fabric alone. First is the concrete-to-primer bond: the substrate must be sound, clean and roughened, with all laitance, oil and unsound concrete removed, and the concrete pull-off (tensile) strength of the prepared surface governs how much load the wrap can ever transfer. A glass laminate is only as good as the Nitowrap 30 bond beneath it. Second is the fibre-to-resin wet-out: the Nitowrap 410 saturant must fully impregnate every strand so the fabric and matrix act as one composite. Dry patches, trapped air or resin-starved zones become weak points where the laminate can delaminate under load. This is why consolidation with a ribbed roller and working within the saturant’s stated pot life (around 120 minutes at 30 C) matters as much as the fibre grade. The cold-cure epoxy chemistry is temperature sensitive: cure is slow in cold weather and pot life shortens sharply in Indian summer heat, so applicators schedule work and batch sizes around ambient temperature. Glass fibre also has a lower elastic modulus than carbon, which means a GFRP wrap is excellent for confinement and ductility (squeezing a column so its core concrete behaves better under axial and seismic load) but is a less efficient choice where a designer needs high added stiffness with minimum thickness, where carbon Nitowrap EP(CF) is usually specified instead.
Where it is used
- Confinement wrapping of RCC columns and piers to raise axial load capacity and ductility
- Shear strengthening of beams and the webs of distressed RCC members
- Flexural strengthening of slabs and beam soffits where increased loading is imposed
- Seismic retrofitting of columns, beam-column joints and load-bearing elements
- Strengthening of masonry walls, arches and masonry bridge structures
- Wrapping of chimneys, tunnels, pipes and other curved or irregular sections
- Restoring capacity to members weakened by corrosion, overloading or design changes
- Strengthening structures in industrial, water-retaining and coastal/aggressive environments where chemical resistance is needed
Key advantages
- Very high strength-to-weight ratio adds structural capacity with negligible increase in dead load
- Member dimensions and headroom are preserved because the laminate is thin and follows the contour
- Improves shear, tensile and confinement capacity and overall stiffness for better seismic performance
- Glass fibre offers excellent resistance to acids and alkalis, suiting aggressive and coastal exposures
- Conformable to any shape or profile, including round columns, curves and irregular sections
- Fast, low-disruption installation needing no heavy plant, ideal for occupied or space-constrained sites
- Generally more economical than carbon FRP for confinement-led and ductility-led strengthening
- Complete, compatible Fosroc system, from epoxy primer and saturant to protective polyurethane topcoat
Limitations & considerations
- Lower elastic modulus than carbon fibre, so less efficient where high added stiffness per layer is needed (consider Nitowrap EP(CF))
- Performance depends entirely on substrate quality, surface preparation and concrete pull-off strength
- Cold-cure epoxy is temperature sensitive: cure slows in cold weather and pot life shortens in hot conditions
- The epoxy matrix needs UV protection (Nitowrap 512 topcoat) on externally exposed structures
- Fibre quantity, layers and orientation must be designed by a qualified structural engineer, not assumed
- Quality is application-critical: dry spots, trapped air or resin starvation cause delamination
- Not a fire-rated finish in itself; additional fire protection may be required by code
- Skilled, trained applicators and clean working conditions are essential for a reliable bond
Selection & best practice
Treat Nitowrap EP(GF) as an engineered system, not a product you simply paint on. Start from a structural design that fixes the number of fabric layers, the fibre direction and the development/anchorage length. Prepare the concrete to a sound, clean, roughened profile by grit blasting or mechanical means, remove all laitance and unsound material, make good blowholes with a Fosroc repair mortar, and check that the substrate is dry and that corners are rounded (typically to about a 20 mm radius) so the fibre is not kinked. Apply Nitowrap 30 primer and let it become tacky, then apply Nitowrap 410 saturant and lay the Nitowrap GF fabric into it in the design orientation, working out all air with a ribbed roller and over-coating with more saturant to fully wet the fibres. Respect the pot life for the ambient temperature, lap successive sheets as specified, and allow proper cure before loading. Finish exposed laminates with Nitowrap 512. Always engage a trained applicator and have the work supervised; FRP strengthening is unforgiving of poor workmanship.
Specifications
| Product type | Glass fibre (GFRP) externally bonded structural strengthening / wrapping system |
| Fibre | E-glass fabric (Nitowrap GF), supplied on rolls 1 m wide |
| Resin matrix | Cold-cured epoxy (Nitowrap 30 primer + Nitowrap 410 saturant) |
| Protective topcoat | Nitowrap 512 polyurethane (grey) for exposed structures |
| Nitowrap 30 primer – pot life | Approx. 20 minutes at 30 C |
| Nitowrap 30 primer – coverage | Approx. 8.0 to 10.0 m2 per litre |
| Nitowrap 410 saturant – pot life | Approx. 120 minutes at 30 C |
| Nitowrap 410 saturant – coverage | Approx. 3.5 to 4.0 m2 per litre |
| Nitowrap 512 topcoat – pot life | Approx. 60 minutes at 30 C |
| Nitowrap 512 topcoat – coverage | Approx. 8.0 to 10.0 m2 per litre |
| Typical pack sizes | Nitowrap GF roll 1 m x 43.9 m; Nitowrap 30 – 3.5 L; Nitowrap 410 – 4 L; Nitowrap 512 – 4 L (confirm current packs with supplier) |
| Application | Cold applied (wet lay-up); design layers and orientation per structural engineer |
| Key uses | Strengthening of columns, beams, slabs, masonry; seismic retrofit |
Industry use cases
Seismic retrofit (public & residential buildings)
Confinement wrapping of columns and beam-column joints brings older RCC framed buildings closer to current seismic code without demolition, a frequent need across Delhi NCR’s higher seismic zone.
Industrial & chemical plants
Glass fibre’s resistance to acids and alkalis makes EP(GF) suitable for strengthening structures in process plants, effluent works and other aggressive industrial environments.
Water & wastewater infrastructure
Wrapping of water-retaining structures, tanks and pipes that need restored or added capacity while resisting chemically loaded environments.
Bridges & transport structures
Strengthening of piers, masonry arches, decks and tunnel linings where increased traffic loading or distress demands extra shear and flexural capacity with minimal added weight.
Commercial change-of-use refurbishment
When floor loadings rise after a change of use, slabs and beams can be strengthened in place with a thin GFRP laminate that preserves headroom and keeps the building operational.
Coastal & marine-adjacent structures
Corrosion-damaged or under-strength elements in coastal projects benefit from a chemically resistant glass wrap that adds capacity without heavy jacketing.
Frequently asked questions
Is Nitowrap EP(GF) a single product or a system?
What is the difference between Nitowrap EP(GF) and Nitowrap EP(CF)?
Can it strengthen columns, beams and slabs?
How important is surface preparation?
Does the wrap need a topcoat?
Does Space Arc Engineering supply the full system across India?
How we position Fosroc Nitowrap EP(GF)
Nitowrap EP(GF) is Fosroc’s glass-fibre strengthening system and sits alongside the carbon-fibre Nitowrap EP(CF), which is specified where higher stiffness with minimum thickness is needed, and the related Nitowrap FRC carbon sheet and Nitowrap CW/CWS/GW wraps for other duties; its epoxy adhesives belong to the Nitobond and Lokfix/Conbextra structural epoxy family. Against the wider market it competes with Sika’s SikaWrap glass fabric with Sikadur saturants, MBS (Master Builders Solutions) MasterBrace FRP systems, and the strengthening lines from STP and Dr. Fixit; all are wet lay-up FRP systems and the right choice usually comes down to the structural designer’s modulus and capacity requirements, local technical support and availability rather than headline fibre type alone. Space Arc Engineering recommends EP(GF) where confinement, ductility and chemical resistance lead the design, and steers clients to the carbon options where the calculations call for maximum added stiffness, with the structural engineer’s design always governing.
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