Fosroc Nitowrap CF
A unidirectional carbon fibre fabric that bonds to concrete with epoxy to add tensile capacity where beams, slabs and columns fall short.
What is it?
A high-strength unidirectional carbon fibre fabric (CFRP) that, once saturated with Fosroc epoxy primer and encapsulation resin, cures into a thin externally-bonded reinforcement layer on concrete.
Where is it used?
Under-strength or distressed RC beams, slabs, columns, pier caps and bridge girders where load has increased or a member has been damaged.
Why use it?
It restores or raises structural capacity without adding meaningful dead load or reducing headroom, and installs faster than steel plating or section enlargement.
How is it applied?
The prepared surface is primed, the carbon fabric is laid into wet saturant resin along the direction of stress, rolled to remove air, and top-saturated before a protective finish.
About Fosroc Nitowrap CF
Nitowrap CF belongs to Fosroc’s family of carbon fibre reinforced polymer (CFRP) strengthening systems. The fabric itself is a unidirectional weave of high-strength carbon filaments, held together just enough to handle on site but engineered to carry load only along the fibre direction. On its own the dry cloth does very little; the performance comes from bonding it to sound concrete with a matched epoxy primer and encapsulation resin. Once cured, the fabric and resin act as a single composite laminate that shares tension with the existing reinforcement, letting a member resist forces it was never originally detailed for.
The technical insight
The mechanism is external bonding: a cured carbon laminate on the tension face of a member picks up strain as the concrete deflects, and because the carbon fibre has a very high modulus, it develops large tensile force at small strains. That force supplements the internal steel in flexure, provides an external tie in shear when wrapped across the web, and applies passive confinement to a column when wound circumferentially so the concrete core behaves as if it were under triaxial stress. The whole load path depends on the epoxy bond line and the concrete substrate, so bond quality, not fibre strength, is usually what governs the design.
Where it is used
- Flexural strengthening of under-reinforced RC beams and one-way or two-way slabs
- Shear strengthening of beams and bridge girders using U-wraps across the web
- Confinement of columns and piers to improve ductility in seismic retrofits
- Restoring capacity to members damaged by corrosion, impact or overloading
- Increasing live-load rating of road and railway bridge decks and pier caps
- Strengthening around new openings cut through existing slabs and walls
- Upgrading industrial floor slabs and framed structures for changed loading
- Reinforcing chimneys, silos, water tanks and towers where access is difficult
Key advantages
- Very high tensile strength-to-weight ratio, so capacity is added with negligible dead load
- Thin laminate profile that barely changes member dimensions or clearance
- Non-corroding carbon fibre suits aggressive, marine and humid environments
- Fast, low-disruption installation with hand tools and no heavy plant
- Fabric conforms to curved, angled and confined surfaces that plates cannot
- Quick return to service compared with section enlargement or steel plating
- Available in a range of fabric weights and thicknesses to tune the design
- Overcoatable with Fosroc protective or decorative finishes for durability
Limitations & considerations
- Performance depends entirely on the epoxy bond and a sound, dry substrate; weak or delaminated concrete must be repaired first
- Carbon fibre is strong but brittle, with limited strain to failure, so debonding must be checked in design
- Unprotected epoxy and carbon are vulnerable to fire and UV, so a finish or fire protection is usually required
- Effective in the fibre direction only; multi-directional demands need multiple orientations or layers
- Application is temperature and humidity sensitive and should not proceed on damp surfaces or above roughly 85% RH
- Not a substitute for proper structural assessment; it must be designed by a competent engineer to ACI 440 or equivalent
Selection & best practice
Start with a structural assessment and a design to ACI 440.2R or fib Bulletin 14 that fixes the fabric grade, layers and orientation. Prepare the concrete to a sound, dry, dust-free surface by light grit blasting, fill blowholes, and grind sharp corners to a radius of at least 10 mm so the fabric is not stress-raised. Apply Nitowrap primer at roughly 0.25 to 0.6 kg/m2, then lay the fabric into wet encapsulation resin along the design direction and roll firmly to expel air and fully wet-out the fibres, keeping resin consumption near 0.60 to 1.0 kg/m2. Respect the resin pot life of about 40 to 50 minutes at 20 degrees C, avoid application on damp substrates or in high humidity, allow full cure, and apply a protective or fire-rated finish after 24 hours.
Specifications
| System type | Unidirectional carbon fibre fabric (CFRP) with epoxy primer and encapsulation resin |
| Fibre tensile strength | >3500 MPa (typical; higher-modulus grades higher) |
| Fibre elastic modulus | >230 GPa (typical) |
| Ultimate elongation | ~1.2-2.1% (grade dependent) |
| Fabric areal weight | 200-600 g/m2 depending on grade |
| Design thickness | 0.111-0.337 mm depending on grade |
| Primer coverage | 0.25-0.6 kg/m2 (surface dependent) |
| Encapsulation resin coverage | 0.60-1.0 kg/m2 (surface dependent) |
| Design standards | ACI 440.2R, fib Bulletin 14, TR55 (UK) |
Industry use cases
Bridges & Infrastructure
Raising live-load rating of road and rail bridge decks, girders and pier caps without closing the structure for lengthy reconstruction.
Commercial & High-Rise
Strengthening beams and slabs for change of use, added plant loads or new openings cut through existing floors.
Seismic Retrofit
Column and pier confinement to boost ductility and shear capacity of framed buildings in seismic zones.
Industrial & Process
Upgrading floor slabs, silos, water tanks and towers where equipment loads have increased or members show distress.
Repair & Rehabilitation
Restoring capacity to members weakened by reinforcement corrosion, impact or historic overloading.
Frequently asked questions
Is Nitowrap CF the same as Nitowrap CW or FRC?
How much load can a carbon fibre wrap add to a beam?
Can it be applied to a damp or green concrete surface?
How much primer and resin do I need per square metre?
Does the carbon fibre need protection after installation?
Do you provide application, or only supply the material?
How we position Fosroc Nitowrap CF
Nitowrap CF sits in Fosroc’s structural strengthening range alongside the related carbon fibre wraps and is used with Fosroc’s epoxy primer and encapsulation/saturant resins as a complete system. Where a design calls for a plate-bonded rather than fabric solution, or a pre-cured laminate, an engineer may prefer those variants, and where the substrate first needs structural repair we typically pair it with Fosroc Renderoc repair mortars and Nitobond bonding agents before wrapping. For projects standardising on other brands, we also supply equivalent CFRP fabric and structural adhesive systems from Sika (SikaWrap / Sikadur) and MC-Bauchemie; the right choice usually comes down to the specifier’s approved-vendor list and the design code being followed.
Related Structural Strengthening products
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