Fosroc Nitowrap CW
High-strength unidirectional carbon fibre fabric system for non-intrusive flexural, shear and seismic strengthening of concrete structures.
What is it?
A high-performance unidirectional carbon fibre (CFRP) fabric that, when saturated with Fosroc’s epoxy primer and saturant resins, bonds to a concrete surface to form a thin, externally-bonded reinforcement layer.
Where is it used?
Beams, slabs, columns, bridge girders, parking decks and chimneys needing added load capacity, seismic upgrade or repair of distressed RCC across India.
Why use it?
It adds very high tensile capacity at negligible dead weight, is non-corrosive, installs fast with almost no loss of headroom, and avoids the disruption of section enlargement or steel plate bonding.
How is it applied?
Repair and prime the substrate with Nitowrap 30, apply Nitowrap 410 saturant, lay the dry fabric in the fibre direction, roll out air, then over-saturate and finish, building up the designed number of layers.
About Fosroc Nitowrap CW
Fosroc Nitowrap CW is a structural strengthening system built around a high-quality unidirectional carbon fibre fabric (CFRP) that is bonded to concrete using a cold-applied epoxy resin matrix. It belongs to the family of externally bonded fibre-reinforced polymer (FRP) systems that have, over the last two decades, become the preferred answer in India when an existing reinforced-concrete element no longer has enough capacity for the load it must carry. Rather than demolishing and recasting, or jacketing a member with extra concrete and steel, the engineer bonds a few tenths of a millimetre of carbon fibre to the tension or shear face and recovers — or increases — the original design capacity.\n\nThe carbon fibres run in one direction, so the strengthening is highly directional: the fabric is laid with its fibres aligned to the principal tensile stress. For a simply-supported beam that means along the soffit for flexure; for shear it means wrapping or U-jacketing across the web; for a column under seismic demand it means circumferential confinement. The fabric itself carries almost no load until it is impregnated with resin — the cured epoxy transfers stress from the concrete substrate into the fibres and holds the laminate together as a composite.\n\nIn the field, Nitowrap CW is rarely supplied alone. It is the reinforcement layer of a three-part system: Nitowrap 30 (a low-viscosity epoxy sealer-cum-primer that penetrates and seals the prepared concrete), Nitowrap 410 (a high-build epoxy saturant that wets out the fabric and acts as the laminating adhesive), and the carbon fabric itself. Together these form the bonded CFRP laminate. For Space Arc Engineering’s clients across Delhi NCR and the rest of India, this makes Nitowrap CW a complete retrofit solution rather than a single material — and one that demands a properly engineered design before a single metre of fabric is cut.
The technical insight
What makes Nitowrap CW versatile is that it is offered in three fibre grades distinguished by elastic modulus, and the right choice is governed by stiffness compatibility, not simply by the highest strength number. The standard-modulus grade (CWS) carries roughly 4,900 MPa fibre tensile strength at a 230 GPa modulus with about 2.1% elongation; the high-modulus grade (CWH) sits near 4,600 MPa at 340 GPa with about 1.4% elongation; and the very-high-modulus grade (CWHM) reaches around 640 GPa but at a much lower rupture strain (about 0.4%). The key engineering point is that a higher-modulus fabric attracts a larger share of strain at low deformation, so it is favoured where deflection or crack control governs (stiffening), whereas the standard grade, with its higher rupture strain, is usually the workhorse for ultimate flexural and shear strengthening. Because the published values are fibre properties measured on the dry fabric, the design must convert them to a laminate basis using the cured cross-section and apply environmental and strain-limit reduction factors per the governing FRP design code. Practically, the very small design thickness per ply (roughly 0.15 to 0.34 mm depending on grade and areal weight) is what lets multiple layers be stacked without altering member geometry or clearances.
Where it is used
- Flexural strengthening of RCC beams and slabs that are under-reinforced or carry increased loads (soffit-bonded fabric)
- Shear strengthening of beam webs using U-wraps or full wraps oriented across the shear plane
- Seismic retrofitting and confinement of columns to improve ductility and axial capacity
- Strengthening of bridge and flyover girders for upgraded live-load classes
- Repair of structurally damaged or corrosion-affected concrete after the cause has been treated
- Strengthening of industrial slabs, parking decks and floors for higher equipment or wheel loads
- Reinforcement of chimneys, silos, water tanks and tunnel linings where added section weight is undesirable
- Restoring capacity lost to design errors, accidental damage, or change of building use/occupancy
Key advantages
- Very high tensile strength (up to ~4,900 MPa fibre strength) at negligible added dead load
- Extremely thin laminate (fractions of a millimetre per ply) so headroom, clearances and member geometry are essentially unchanged
- Carbon fibre does not corrode, giving long service life and suiting marine, coastal and aggressive environments
- Fast, non-intrusive installation with minimal demolition, dust and downtime — quick return to service
- Fabric conforms to angles, curves and contours without pre-fabrication, unlike rigid steel plates or CFRP plates
- Available in three moduli (CWS / CWH / CWHM) so the system can be tuned to strength-governed or stiffness-governed problems
- Dry or wet lay-up techniques possible, and multiple layers can be built up to meet design demand
- No heavy lifting plant required compared with steel-plate bonding or concrete jacketing
Limitations & considerations
- Strengthening is unidirectional — fibres carry load only along their axis, so orientation is critical and a wrong layup direction is structurally useless
- Mandatory engineered design: ply count, layout and anchorage must be calculated and signed off by a qualified structural engineer per the applicable FRP code
- Performance depends entirely on substrate bond — concrete must be sound, repaired, dry and properly primed; debonding causes premature failure
- Epoxy matrix is sensitive to temperature: glass-transition limits mean unprotected CFRP loses capacity in fire, so fire protection is usually required
- Carbon fibre is electrically conductive and can drive galvanic corrosion if placed in direct contact with steel without isolation
- Site application demands trained applicators; air voids, poor saturation or fibre misalignment sharply reduce effectiveness
- Adds tensile capacity but little compressive contribution, and does not by itself solve the underlying durability cause (e.g. ongoing rebar corrosion)
- Higher material cost per square metre than conventional repair, justified only where speed, weight or geometry rule out alternatives
Selection & best practice
Always begin with a structural assessment and an engineered FRP design that fixes the grade, number of plies, fibre orientation and end anchorage — never specify Nitowrap CW by area alone. Treat the root cause first: if rebar is corroding, complete concrete repair and passivation before wrapping, because CFRP seals the surface and can mask continuing deterioration. Prepare the substrate by grinding to expose sound concrete, rounding off sharp arrises to at least the radius required for wrapped corners, and removing dust; the surface must be dry with pull-off strength meeting the design minimum. Prime with Nitowrap 30, allow the correct tack interval, apply Nitowrap 410 saturant, lay the fabric strictly in the fibre direction, and roll thoroughly in one direction to expel air before the over-coat. Maintain the specified resin consumption per layer, respect overlap lengths, and protect the finished laminate with a UV-resistant top coat and, where codes require, a fire-protective render. Keep work within the resin’s temperature and humidity window and engage a trained, Fosroc-approved applicator.
Specifications
| Product type | Unidirectional carbon fibre fabric (CFRP) for externally bonded reinforcement |
| Available grades | CWS (standard modulus), CWH (high modulus), CWHM (very high modulus) |
| Fibre tensile strength | CWS ~4,900 MPa; CWH ~4,600 MPa; CWHM ~1,900 MPa |
| Fibre elastic modulus | CWS 230 GPa; CWH 340 GPa; CWHM 640 GPa |
| Elongation at break | CWS ~2.1%; CWH ~1.4%; CWHM ~0.4% |
| Fibre density | CWS 1.8 g/cm³; CWH 1.82 g/cm³; CWHM 2.12 g/cm³ |
| Areal weight | approx. 300–450 g/m² (grade dependent) |
| Design thickness per ply | approx. 0.145–0.337 mm (grade and areal weight dependent) |
| Associated primer | Nitowrap 30 epoxy sealer-cum-primer (approx. 0.25–0.3 kg/m²) |
| Associated saturant | Nitowrap 410 high-build epoxy saturant / laminating resin |
| Application technique | Dry wrap (primary); wet wrap on consultation; multiple layers as designed |
| Resin packaging | Primer / saturant supplied in 15 kg packs |
| Shelf life | Resins: 12 months in original packing, stored cool and dry; fabric: effectively unlimited in dry covered storage |
| Design basis | Layup designed and approved by a licensed structural engineer per the prevailing FRP design code |
Industry use cases
Bridges & Highways
Upgrading the live-load rating of ageing RCC bridge and flyover girders by bonding carbon fabric to soffits and webs, avoiding traffic-blocking reconstruction on busy NCR and national-highway corridors.
Commercial & Retail Buildings
Strengthening beams and slabs when an occupancy or use changes (e.g. office converted to records storage or a gym) increases imposed loads beyond the original design.
Industrial & Manufacturing
Reinforcing factory floor slabs and supporting beams for heavier machinery, racking or forklift loads without casting new structure or losing production time.
Seismic Retrofitting
Confining columns and strengthening beam-column joints in existing buildings being brought up to current IS seismic detailing in zones III–V.
Water & Wastewater
Restoring capacity in tanks, sumps and treatment structures where added concrete jacketing weight or reduced internal clearance is unacceptable.
Repair & Rehabilitation Contractors
A fast, low-weight remedial option for distressed or accidentally damaged members in multi-storey buildings where demolition is impractical.
Frequently asked questions
Is Fosroc Nitowrap CW a real product?
What is the difference between the CWS, CWH and CWHM grades?
Which resins are used with Nitowrap CW?
How is Nitowrap CW different from Fosroc Nitowrap EP(CF) or Nitoplate CFRP plates?
How does it compare with Sika, MBCC/MBS, Dr. Fixit or STP systems?
Can Nitowrap CW be applied to any cracked or damaged concrete?
Does it need fire protection?
How we position Fosroc Nitowrap CW
Within Fosroc’s strengthening range, Nitowrap CW is the carbon fibre fabric solution for problems with curved geometry, column confinement or seismic confinement, where a conformable wrap beats a rigid plate. It sits alongside Fosroc’s pre-cured CFRP plate/laminate options (used for straightforward flexural soffit strengthening) and is supported by Fosroc’s wider concrete-repair line — repair mortars such as the Renderoc range and protective coatings — which should be used to make the substrate sound before wrapping. Compared with traditional methods, it competes against steel-plate bonding and RCC/steel jacketing, beating both on weight, speed and corrosion resistance while costing more per square metre. Against the market, it is a direct alternative to Sika SikaWrap (with Sikadur resins), Master Builders/MBS MBrace, STP carbon wrap and Dr. Fixit (Pidilite) structural carbon systems — all technically similar externally bonded CFRP. Space Arc Engineering’s honest guidance to NCR and Pan-India clients: specify Nitowrap CW when speed, low added weight or complex geometry rule out conventional strengthening and when you want full Fosroc system compatibility; treat the design as the deciding factor, and choose any reputable brand whose approved design data and trained applicators best fit your project and timeline.
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