Sika SikaWrap-601 C IN
India-made 600 g/m2 unidirectional carbon fibre fabric for externally bonded flexural, shear and seismic strengthening of concrete, masonry and timber.
What is it?
A woven unidirectional carbon fibre fabric (95% carbon warp, 5% glass weft) at 600 g/m2, manufactured in India, used with Sikadur epoxy resins to build a CFRP laminate that bonds to the outside of a structural member.
Where is it used?
On RC beams, slabs, columns, bridge girders, masonry walls and timber where extra load capacity, seismic ductility or repair of corroded reinforcement is needed without adding much dead weight or section.
Why use it?
It adds high tensile strength (around 4,900 N/mm2) exactly where a member is deficient, is far lighter than steel plating, and can be installed in occupied buildings with minimal downtime.
How is it applied?
Wet lay-up: prepare and prime the substrate with Sikadur-330 IN, saturate the fabric with Sikadur-300 IN, roll it firmly onto the primed surface along the load direction, then consolidate to remove air and wet-out fully.
About Sika SikaWrap-601 C IN
SikaWrap-601 C IN is a heavy, unidirectional carbon fibre fabric engineered for the externally bonded reinforcement (EBR) of structural members. The fabric is woven with roughly 95% high-strength carbon warp fibres running in the 0-degree direction and a light 5% heat-set glass weft that holds the carbon rovings straight and evenly spaced until they are impregnated on site. Because virtually all the strength runs one way, the engineer can orient the fabric precisely along the tensile stress path, whether that is the soffit of a beam, the face of a slab or a wrap around a column. Manufactured in India, it removes the import lead times that used to slow down strengthening jobs while keeping the full Sika system pedigree and traceable test data behind every roll.
On its own the dry fabric does very little; it becomes a structural material only once it is saturated with the paired Sikadur epoxy resins and bonds to a correctly prepared substrate. Sikadur-330 IN acts as the primer and first bonding coat, and Sikadur-300 IN is the impregnating and laminating resin that wets out the fibres and locks the cured composite to the concrete. The result is a thin carbon-fibre-reinforced polymer (CFRP) laminate, only a fraction of a millimetre thick per ply, that carries load in tension with almost no added weight or change in member size. This makes it a practical answer where load requirements have increased, where reinforcement has corroded, or where a structure must be brought up to current seismic codes without demolition.
The technical insight
The mechanism is straightforward force transfer through a bonded interface. Carbon fibre is exceptionally strong and stiff in tension but does almost nothing in compression or across its width, so the design intent is to run the 0-degree fibres directly along the line of tensile stress. When a loaded RC beam deflects, its tension face wants to elongate; the bonded CFRP laminate, stiff at about 250,000 N/mm2 tensile modulus, resists that elongation and picks up a share of the tensile force that the original steel or cracked concrete can no longer carry. Everything hinges on the epoxy bond line, which is why Sika specifies a minimum substrate pull-off strength of 1.0 N/mm2 and a sound, laitance-free surface. The 5% glass weft is not structural; it is a handling aid that keeps the unidirectional carbon tows parallel and prevents them splaying before the resin sets. With an elongation at break near 2.1%, the composite stays well within elastic behaviour under service loads, and the thin 0.330 mm dry-fibre thickness per ply lets designers stack plies to reach a target reinforcement area without meaningfully altering the member’s geometry or self-weight.
Where it is used
- Flexural strengthening of RC beams and slab soffits where bending capacity is deficient
- Shear strengthening of beams via U-wraps or side bonding across the web
- Seismic retrofit and confinement of columns to improve ductility and load capacity
- Upgrading floor slabs to carry higher imposed or point loads after a change of use
- Restoring capacity to members where embedded reinforcement has corroded and lost section
- Reinforcement of unreinforced or cracked masonry and brickwork walls
- Strengthening of timber structural members needing added tensile capacity
- Repair and upgrade of bridge girders, decks and industrial structures with restricted downtime
Key advantages
- Very high tensile strength (around 4,900 N/mm2) delivered at negligible added dead load
- Unidirectional weave lets fibres be aligned exactly with the tensile stress path
- Thin 0.330 mm laminate per ply barely changes member size or clearances
- Corrosion-free composite, unlike bonded steel plate, so no future rust jacking
- India-manufactured, shortening lead times while retaining the full Sika system data
- Conformable fabric wraps beams, columns and irregular profiles cleanly
- Fast wet lay-up installation means occupied buildings return to service quickly
- Backed by a matched Sikadur-330 IN / Sikadur-300 IN resin system for reliable bond
Limitations & considerations
- Performs in tension only along the 0-degree fibres; contributes little in compression or across the weave
- Entirely dependent on the epoxy bond, so a substrate below 1.0 N/mm2 pull-off strength makes it unusable until repaired
- Epoxy resins are temperature and humidity sensitive during cure and are not for permanently wet or submerged conditions without extra protection
- Untreated CFRP has limited fire and UV resistance and needs a protective overcoat or render where exposed
- Requires trained applicators and proper design; it is not a general-purpose over-the-counter repair material
- Effectiveness is capped by the strength of the existing concrete and its ability to transfer load into the laminate
Selection & best practice
Success is decided at the substrate. Grind or grit-blast the concrete to remove laitance and expose a sound, clean profile, round off sharp corners on any wrapped elements to avoid stress concentrations, and confirm a minimum pull-off tensile strength of 1.0 N/mm2 before starting. Repair spalls and reprofile with a suitable Sika mortar so the surface is even. Prime and apply the first bonding coat with Sikadur-330 IN, then saturate the fabric with Sikadur-300 IN and lay it strictly along the design fibre direction, working from the centre outwards with a ribbed roller to fully wet out the carbon and drive out entrapped air. Overlap laps as specified, respect the resin pot life and the substrate and ambient temperature window, and allow the system to cure undisturbed. Where the laminate is exposed to sunlight, fire risk or view, finish with a protective coating or render. Always work to the project structural engineer’s design and the current Sika data sheets rather than by rule of thumb.
Specifications
| Fibre type & orientation | High-strength carbon, 0 degree (unidirectional) |
| Fabric composition | 95% carbon warp, 5% heat-set glass weft |
| Areal weight | 600 g/m2 plus/minus 30 g/m2 (carbon fibres only) |
| Dry fabric thickness | 0.330 mm (based on fibre content) |
| Tensile strength | 4,900 N/mm2 (ISO 10618) |
| Tensile modulus of elasticity | 250,000 N/mm2 (ISO 10618) |
| Elongation at break | 2.1% (ISO 10618) |
| Roll size | 500 mm wide, length >= 50 m per roll |
| Resin system | Sikadur-330 IN primer + Sikadur-300 IN saturant |
Industry use cases
Commercial & IT buildings
Upgrading beams and slabs when floors are re-purposed for heavier server rooms, filing loads or new plant without recasting members.
Bridges & infrastructure
Flexural and shear strengthening of girders and decks to carry higher traffic loads with short lane-closure windows.
Seismic retrofit
Confining columns and reinforcing beam-column joints in older RC frames being brought up to current seismic codes.
Industrial & plant structures
Restoring capacity to beams and supports weakened by reinforcement corrosion in aggressive or humid process environments.
Heritage & masonry
Discreet, low-added-mass reinforcement of cracked masonry walls and older structures where demolition is not an option.
Frequently asked questions
What exactly is SikaWrap-601 C IN made of?
Which resins do I need with it?
How much resin will a job consume?
What condition does the concrete need to be in?
Can it be used for seismic strengthening?
Do I need special coatings over the finished wrap?
How we position Sika SikaWrap-601 C IN
SikaWrap-601 C IN is the heavy 600 g/m2 carbon option in Sika’s externally bonded reinforcement range and is only ever specified as a system with its Sikadur-330 IN primer and Sikadur-300 IN saturant, so those resins should be ordered alongside the fabric. Where a project calls for a lighter carbon fabric or a glass-fibre alternative, other SikaWrap grades cover those cases; for cast-in-place or high-modulus needs, the wider Sika strengthening portfolio and Sikadur structural adhesives round out the specification. As an authorised distributor and applicator for multiple brands across Delhi NCR and pan-India, Space Arc can also supply equivalent systems from Fosroc where a client standardises on that brand. We recommend the product that matches the engineer’s design and the client’s approved vendor list rather than pushing a single label.
Fosroc Nitowrap CW — A specifier standardised on the Fosroc system, or matching an existing Fosroc-approved structural strengthening spec, may prefer Nitowrap CW as the directly equivalent unidirectional carbon fibre wrap.
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