Sika SikaWrap-230 C
Unidirectional carbon fibre fabric for externally bonded strengthening of concrete, steel and masonry, applied wet in the field with Sikadur epoxy resins.
What is it?
A dry, unidirectional woven carbon fibre fabric (CFRP) that is site-saturated with a Sikadur epoxy and bonded to a structure to add high-strength external reinforcement.
Where is it used?
Beam soffits, slab and deck undersides, columns, masonry walls, arches, chimneys and any RC or masonry member needing added load capacity or seismic confinement.
Why use it?
Adds significant tensile capacity at a fraction of the weight and thickness of steel plating, with almost no change to member dimensions and no corrosion risk.
How is it applied?
Prime and level the substrate, apply Sikadur-330 or Sikadur-300, then hand-lay the fabric along the fibre direction and roll through to full saturation, adding layers as designed.
About Sika SikaWrap-230 C
SikaWrap-230 C is Sika’s workhorse carbon fibre fabric for externally bonded reinforcement, and it is the sheet most Indian rehabilitation contractors reach for when a beam, slab or column has to carry more than it was designed for. The fabric is woven from high-strength carbon filaments laid in a single 0-degree direction, held in position by a fine thermoplastic heat-set weft thread. That construction means the fabric carries load only along the fibres, so the designer aligns the roll precisely with the direction of the tensile stress being resisted. Because the fabric arrives dry, it is light to transport, easy to cut to shape on site, and can be wrapped around curved columns and irregular soffits that rigid plates simply cannot follow.
The strengthening only develops once the fabric is impregnated with a Sikadur epoxy and cured against a sound substrate. Sika pairs the sheet with Sikadur-330, a thixotropic adhesive for the dry lay-up method, or Sikadur-300, a lower-viscosity resin for the wet lay-up method where the fabric is pre-saturated before placement. The cured carbon-epoxy laminate becomes a thin, stiff composite bonded to the concrete, so incoming forces transfer through the adhesive into the fibres. For Indian projects the appeal is practical: an ageing flyover girder, a factory floor slab facing heavier equipment, or a column that must meet revised seismic demand can all be upgraded in place, without the shoring, welding and long shutdowns that steel jacketing or section enlargement demand.
The technical insight
The mechanics come down to putting a very stiff, very strong material exactly where the structure is weakest in tension. Concrete cracks and yields in tension long before it crushes in compression, so a beam soffit or a slab underside is the natural place to bond fibres. Carbon fibre has a tensile modulus of roughly 230,000 N/mm2 and a fibre tensile strength near 4,000 N/mm2, which is why it can restrain crack opening and share load with the internal steel almost immediately. The 0-degree unidirectional weave concentrates every filament along that one working axis, so at only about 0.129 mm of dry fibre thickness the composite still delivers a design tensile resistance in the order of hundreds of kN per metre of width. The epoxy is not a bystander: it is the shear medium that transfers stress from the concrete surface into the fibres, which is why substrate soundness and a minimum pull-off strength of about 1.0 N/mm2 govern whether the system performs at its rated capacity or peels prematurely. Wrapped continuously around a column, the same fabric acts in the hoop direction, confining the core so that concrete under seismic load behaves in a more ductile way.
Where it is used
- Flexural strengthening of RC beams, deck slabs and cantilever soffits carrying increased loads
- Shear strengthening of beams and joints using vertical or inclined fabric strips or U-wraps
- Seismic confinement of columns to raise ductility and axial capacity in retrofit projects
- Restoration of load capacity in slabs and beams weakened by corrosion, cracking or overload
- Strengthening of masonry walls, arches, domes and heritage structures against out-of-plane forces
- Reinforcement of chimneys, silos, tanks and other cylindrical or curved structures
- Upgrading floors and framed members before a change of use or heavier equipment installation
- Repair of members damaged by impact, fire or long-term deflection where dimensions must stay unchanged
Key advantages
- Extremely high strength-to-weight ratio adds major tensile capacity with negligible added dead load
- Very thin cured laminate leaves member dimensions and clear headroom essentially unchanged
- Non-corroding carbon-epoxy composite suits marine, coastal and chemically aggressive environments
- Dry fabric conforms to columns, curves and irregular soffits that rigid steel plates cannot follow
- Fast, largely manual installation needs no hot works, heavy lifting or long structural downtime
- Backed by an engineered Sika system of matched primers, epoxies and design methodology
- Unidirectional weave lets the designer place full fibre strength precisely along the stress path
- Widely accepted internationally for FRP strengthening, giving consultants a well-documented basis for design
Limitations & considerations
- Performance depends entirely on a sound substrate with adequate pull-off strength; weak or contaminated concrete must be repaired first
- Bare carbon-epoxy has limited fire and UV resistance and normally needs a protective render or coating in exposed conditions
- Epoxy saturation and curing are temperature and humidity sensitive, so ambient and substrate conditions must fall within Sikadur limits
- It strengthens in tension and confinement only; it does not fix underlying causes such as active corrosion or foundation movement
- Correct design, surface preparation and skilled wet lay-up are essential, so it is specialist rather than general-purpose work
- Anchorage and lap detailing must be engineered, since premature debonding can limit the strength actually achieved
Selection & best practice
Treat the fabric as one part of an engineered system, not a standalone product. Start with a structural assessment and a design that fixes the fibre direction, number of layers and anchorage. Prepare the substrate to expose sound, open-textured concrete, repair spalls and carbonated cover first, round off sharp column corners to a suitable radius, and confirm a pull-off strength of at least about 1.0 N/mm2. Mix and apply the matched Sikadur resin within its stated temperature window, lay the fabric strictly along the design fibre direction, and roll it firmly to drive out air and achieve full saturation before adding further layers wet-on-wet as specified. Allow full cure before loading, then protect exposed laminates with a suitable render or coating for fire and UV cover. Keep the work to trained applicators and record surface conditions and consumption for QA.
Specifications
| Fibre type | Carbon, 0-degree unidirectional woven fabric |
| Areal weight | 235 g/m2 (approx.) |
| Fibre density | 1.82 g/cm3 |
| Dry fibre thickness | 0.129 mm |
| Fibre tensile strength | ~4,000 N/mm2 |
| Tensile E-modulus | ~230,000 N/mm2 |
| Elongation at break | ~1.7% |
| Laminating resins | Sikadur-330 (dry lay-up) or Sikadur-300 (wet lay-up) |
| Roll dimensions | 300 mm or 600 mm width, 50 m length |
Industry use cases
Bridges & Infrastructure
Flexural and shear upgrading of girders, deck slabs and piers to carry revised traffic loads or extend service life without replacement.
Commercial & Industrial Buildings
Strengthening floor slabs and beams before heavier machinery, storage racking or a change of occupancy raises design loads.
Seismic Retrofit
Column confinement and joint strengthening to meet updated seismic codes on existing RC frames across earthquake-prone zones.
Heritage & Masonry
Discreet reinforcement of arches, domes and load-bearing walls where added steel or thickness would be visually or structurally unacceptable.
Repair & Rehabilitation
Restoring capacity to members degraded by corrosion, cracking, fire or overload while keeping the original member geometry.
Frequently asked questions
Is SikaWrap-230 C ready to use on its own?
How much epoxy will I need per square metre?
How many layers can be applied?
Does the fabric need surface protection after installation?
What condition does the concrete need to be in?
Can Space Arc help with design and application in Delhi NCR and Pan-India?
How we position Sika SikaWrap-230 C
SikaWrap-230 C sits at the core of Sika’s externally bonded reinforcement range and is chosen when carbon’s high stiffness suits demanding flexural, shear or seismic upgrades. Where the design calls for a higher-modulus carbon sheet, SikaWrap-231 C is the natural step up within the same family; where E-glass economy or dielectric behaviour is preferred over carbon stiffness, a SikaWrap glass fabric is the alternative. In every case the fabric must be paired with the matched Sikadur laminating resin (Sikadur-330 or Sikadur-300) and Sika primers, and for surface repair before wrapping our SikaTop and Sika MonoTop mortars complete the system. Across our other lines, Fosroc’s Nitowrap range and the associated Renderoc repair mortars cover the same strengthening and repair need, so we can specify whichever brand the consultant has approved.
Fosroc Nitowrap CWS — Choose the Fosroc carbon fibre wrap system when the project specification, approved-vendor list or existing Nitowrap repair scheme is already standardised on Fosroc rather than Sika.
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