Sika SikaWrap-901 C IN
A heavyweight 900 gsm unidirectional carbon fibre fabric that bonds high-tensile reinforcement onto beams, columns and slabs without adding meaningful dead load.
What is it?
A woven, unidirectional carbon fibre fabric (95% carbon warp, 5% heat-set glass weft) that is wet-laid into a two-part epoxy on site to form an externally bonded FRP laminate.
Where is it used?
Retrofitting and upgrading reinforced concrete, masonry, brickwork and timber members — beams, columns, slabs, walls and bridge elements needing more flexural, shear or axial capacity.
Why use it?
It delivers roughly 4,900 N/mm2 dry-fibre tensile strength at 0.5 mm design thickness, so you add substantial load capacity and seismic ductility with almost no increase in section size or weight.
How is it applied?
Prepare the substrate to a sound, open-textured, laitance-free surface, prime with Sikadur-330 IN, saturate the fabric with Sikadur-300 IN, roll it onto the member along the load direction and consolidate to remove air.
About Sika SikaWrap-901 C IN
SikaWrap-901 C IN is Sika’s high-grammage carbon fibre fabric for externally bonded reinforcement, and it sits at the heavier end of the SikaWrap family. The fabric is woven unidirectionally so that 95 percent of the material runs as continuous black carbon filaments in the warp direction, with just 5 percent of heat-set glass yarn in the weft to hold the sheet together and keep the fibres straight during handling. At 900 g/m2 areal weight it carries considerably more carbon per square metre than the lighter 200-300 gsm grades, which means fewer plies are needed to reach a target capacity — a real advantage when access is tight or a member has to be wrapped quickly during a shutdown.
On its own the dry fabric does nothing structural; it becomes a laminate only once it is impregnated with Sika’s epoxy system on site. The Sikadur-330 IN primer wets out the concrete and gives the bond line something to key into, and the Sikadur-300 IN saturant carries the fibres and cures into a stiff, continuous matrix. That wet-lay approach is what makes the product so adaptable — the same roll can be shaped around a circular column, taken over a beam soffit, or run in strips for shear, because the fabric conforms to the contour before the resin sets. For engineers in India dealing with ageing RCC stock, seismic re-rating and load upgrades, it is a practical way to add tensile reinforcement where casting new concrete or adding steel is impossible.
The technical insight
The mechanism is straightforward composite action: concrete is strong in compression but weak in tension, and carbon fibre is the opposite. By bonding a stiff, high-strength CFRP skin onto the tension face or around a member, you give the section an external tensile element that engages as soon as the concrete tries to crack or the column tries to dilate under load. Because the carbon runs unidirectionally, its full 4,900 N/mm2 strength and roughly 250,000 N/mm2 modulus act along the fibre line — so the designer orients the fabric deliberately: longitudinally for flexure, transversely for shear, and as a continuous hoop for confinement. In confinement the wrap works passively; it does little until the concrete core wants to expand laterally, then the hoop tension in the carbon restrains that dilation, raising both the effective compressive strength and the ductility of the column. The whole system lives or dies on the epoxy bond, which is why the substrate must reach at least 1.0 N/mm2 pull-off strength — the fibre can only deliver its capacity if the resin can transfer shear from the concrete into the laminate without the bond line peeling first.
Where it is used
- Flexural strengthening of RCC beams and slabs by bonding fabric to the tension face
- Shear strengthening of beams using U-wraps or side-bonded transverse strips
- Seismic confinement of columns to increase ductility and axial capacity
- Restoring capacity lost to corrosion, overloading or accidental damage
- Upgrading members to carry higher live loads after a change of building use
- Reinforcing masonry, brickwork and unreinforced walls against out-of-plane loads
- Strengthening timber beams and bridge elements where added dead load must be avoided
- Retrofitting structures to meet current IS seismic and load codes without recasting
Key advantages
- Very high strength-to-weight ratio — large capacity gain with negligible added dead load
- 900 gsm grammage means fewer plies to reach a target design, saving labour and cure time
- Unidirectional carbon lets you place strength precisely along the load path
- Thin 0.5 mm laminate keeps clear headroom and dimensions almost unchanged
- Fully corrosion-proof reinforcement, unlike bonded steel plates
- Conforms to columns, soffits, curves and irregular profiles during wet lay-up
- Excellent fatigue and creep behaviour under sustained and cyclic loading
- Backed by Sikadur epoxies as a matched, warrantable strengthening system
Limitations & considerations
- Purely a design-led product — plies, layout and anchorage must be engineered by a competent structural designer, not chosen by rule of thumb
- Structurally effective only in the fibre direction; misorientation wastes capacity
- Performance depends entirely on substrate quality — concrete must reach at least 1.0 N/mm2 pull-off before wrapping
- Epoxy cures poorly in cold, damp or contaminated conditions, so site control of temperature and surface prep is critical
- Carbon fibre loses strength in fire and needs a protective coating or render for fire rating and UV exposure
- Not a repair mortar — spalled or delaminated concrete must be reinstated first before the wrap goes on
Selection & best practice
Treat the wrap as one part of a three-step system and get each step right. Start by making the concrete sound: repair spalls and honeycombing, grind back to an open-textured, laitance-free surface, round off sharp arrises to at least a 20 mm radius on columns so the fabric is not cut by corners, and confirm the substrate reaches a minimum 1.0 N/mm2 pull-off strength. Prime with Sikadur-330 IN onto a dry, clean surface, then apply the Sikadur-300 IN saturant and lay the fabric strictly along the design fibre direction, working the resin through with a ribbed roller until the weave is fully wetted and no air is trapped. Respect the stated consumption — roughly 0.8 to 1.2 kg/m2 of resin for the first primed layer and 0.5 to 0.8 kg/m2 for subsequent layers — and maintain lap lengths and end anchorage exactly as the designer specifies. Protect exposed laminates with an appropriate top coat for UV and fire, and keep the work above the minimum cure temperature throughout.
Specifications
| Fabric type | Woven unidirectional carbon fibre fabric (0 degree) |
| Fibre composition | 95% carbon warp, 5% heat-set glass weft |
| Areal weight | 900 g/m2 (plus/minus 45 g/m2) |
| Dry fibre density | 1.80 g/cm3 |
| Dry fibre tensile strength | 4,900 N/mm2 |
| Dry fibre tensile E-modulus | 250,000 N/mm2 |
| Elongation at break | 2.1% |
| Design (dry fibre) thickness | 0.500 mm |
| Roll dimensions | 500 mm wide, minimum ~50 m per roll |
Industry use cases
Commercial & Institutional Buildings
Re-rating beams and slabs for heavier office, retail or equipment loads when a building changes use, without recasting members or losing floor height.
Bridges & Infrastructure
Adding flexural and shear capacity to girders and deck elements, and confining piers for seismic upgrade, while keeping added dead load to a minimum.
Seismic Retrofit
Column confinement wraps that boost ductility and axial capacity so older RCC frames can meet current IS seismic demand.
Industrial & Corrosion Repair
Restoring the capacity of RCC members degraded by corrosion or chemical exposure in plants, using a reinforcement that will not itself corrode.
Heritage & Masonry
Strengthening brick and stone walls against out-of-plane loads and reinforcing timber members where intervention must stay thin and reversible-looking.
Frequently asked questions
Is SikaWrap-901 C IN a complete system on its own?
How many layers do I need?
What condition does the concrete need to be in?
How does the 900 gsm grade compare to lighter SikaWrap fabrics?
Does it need protection after installation?
Can Space Arc help size the wrap for my structure?
How we position Sika SikaWrap-901 C IN
SikaWrap-901 C IN is the heavyweight option in Sika’s carbon fibre range; where a project needs a lighter or thinner laminate, or where a design has been written around a specific grammage, the lower-gsm SikaWrap carbon fabrics may suit better, and both must be paired with the Sikadur-330 IN primer and Sikadur-300 IN saturant that Space Arc supplies alongside them. For teams standardised on a different manufacturer, Space Arc also stocks a genuine Fosroc equivalent, and can advise across brands rather than pushing a single line.
Fosroc Nitowrap EP(CF) — A specifier already standardised on Fosroc’s Nitowrap system — using Nitowrap 30 primer and Nitowrap 410 saturant — may prefer this equivalent unidirectional CFRP fabric for continuity of documentation and site familiarity.
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