Sika SikaWrap-900 C
A heavy 865 g/m2 unidirectional carbon fibre fabric for wet-layup strengthening of beams, columns and slabs where high tensile capacity per layer matters.
What is it?
A stitched, unidirectional carbon fibre fabric (865 g/m2 of carbon) used as externally bonded reinforcement in the Sika structural strengthening system.
Where is it used?
On reinforced concrete, masonry, brickwork and timber members that need added flexural, shear or confinement capacity, including seismic retrofits.
Why use it?
It delivers a very high tensile contribution in a single wet-applied layer, so specifiers can meet a strengthening demand with fewer plies and less labour.
How is it applied?
Wet layup: prime the prepared substrate with Sikadur-330, saturate and bond the fabric with Sikadur-300, then consolidate to remove air and wet out the fibres.
About Sika SikaWrap-900 C
SikaWrap-900 C is Sika’s heavy-grade carbon fibre fabric for externally bonded reinforcement (EBR). It is a unidirectional weave — the load-carrying black carbon fibres run in one direction (0 degrees) and make up 96 percent of the material, held straight and handleable by a light stabilising fleece and white stitch yarn that account for the remaining 4 percent. The defining number is its areal density: 865 g/m2 of carbon (plus or minus 45 g/m2), which is more than double the fibre content of a typical 300 g/m2 wrap. That heavy grammage is the whole point of the product. Where a light fabric might need three or four plies to reach a target design force, SikaWrap-900 C can often do it in one or two, which cuts installation time, reduces the total resin used and simplifies detailing at anchorages and laps.
The fabric is a dry system: it arrives with no resin in it and is impregnated on site as part of the wet application process. Space Arc supplies it alongside its companion resins — Sikadur-330 as the substrate primer and Sikadur-300 as the impregnating and laminating resin — because the fabric is surface-treated specifically to bond with those Sikadur adhesives. It is not a standalone product; it is one component of an engineered system, and the fabric, primer and saturant are meant to be used together and not swapped for parts from another system. For engineers and consultants across Delhi NCR and pan-India, that combination of very high per-layer capacity and a fully documented, code-referenced system is why the 900 C gets specified on demanding retrofit and upgrade work.
The technical insight
Externally bonded FRP works by borrowing the carbon fibre’s enormous stiffness and strength and coupling it to the concrete through the epoxy bond line. On its own, the dry fibre reports roughly 3,800 N/mm2 tensile strength, a modulus around 242,000 N/mm2 and only about 1.43 percent elongation at break — it is stiff and strong but brittle, and useless until it is bonded. The resin does two jobs: it wets out every filament so the whole bundle shares load evenly, and it transfers stress from the concrete into the fibres through shear across the glue line. That is why substrate quality is not a footnote but a controlling design input. Sika sets a minimum substrate tensile (pull-off) strength of 1.0 N/mm2, and the surface must be clean, sound and open-textured with all laitance removed; if the concrete lets go, the strengthening lets go with it, because the composite can only pull as hard as its weakest interface. Expressed as a finished laminate at the nominal 0.478 mm design thickness, one layer gives a characteristic tensile resistance of about 1,147 N/mm width (average around 1,434 N/mm) — this is the force-per-metre figure a designer actually uses to size the strengthening. The unidirectional layout matters too: because every fibre points along the tension line, none of the material is wasted resisting off-axis loads, which is exactly what you want for flexural soffit plates, shear U-wraps and column confinement.
Where it is used
- Flexural strengthening of RC beams and slab soffits where fibres are bonded along the span in the tension zone
- Shear strengthening of beams and girders using U-wraps or side-bonded strips
- Confinement of RC columns to raise axial capacity and ductility for seismic retrofit
- Upgrading structural members to carry higher loads after a change of use or added floors
- Replacing or supplementing missing, corroded or under-designed steel reinforcement
- Improving the seismic performance of masonry and brickwork walls
- Correcting original design or construction deficiencies without demolition
- Extending service life and durability of ageing concrete and heritage structures
Key advantages
- Very high carbon content at 865 g/m2, so a large tensile capacity is achieved in fewer plies
- High per-layer force capacity (characteristic tensile resistance about 1,147 N/mm width) reduces layup labour
- Unidirectional fibres put all the material to work directly along the line of tension
- Low added self-weight — the finished laminate adds negligible dead load to the structure
- Flexible dry fabric conforms to beams, columns, chimneys, piles, soffits and curved surfaces
- Far less disruptive and faster than section enlargement, steel plating or member replacement
- Backed by internationally recognised design frameworks (ACI 440.2R and Concrete Society TR55)
- Engineered, matched system with Sikadur-330 primer and Sikadur-300 saturant for reliable bond
Limitations & considerations
- Not a DIY or general-trades product — installation must be done by trained, experienced FRP applicators
- Every scheme needs design by a specialist structural engineer; the fabric contributes nothing without correct detailing
- Performance is capped by substrate condition, which must reach a minimum 1.0 N/mm2 pull-off strength
- System components must not be interchanged — the fabric is coated to bond specifically with Sikadur resins
- The dry, unprotected laminate needs an overcoat (for example Sikagard) where UV, fire or aesthetics require it
- Being brittle, carbon FRP gives limited warning before rupture, so design must respect strain limits and safety factors
Selection & best practice
Treat the substrate as the make-or-break step. Grind or grit-blast the concrete to a sound, open-textured, laitance-free surface, repair spalls and honeycombing first, and confirm the pull-off strength is at least 1.0 N/mm2 before any resin goes on. Cut the fabric to length with special scissors or a sharp blade and never fold it — folds kink and break fibres. Apply Sikadur-330 primer at 0.6 to 0.8 kg/m2, then wet-apply the fabric with Sikadur-300 at about 1.0 kg/m2 per layer, working from the centre outwards with a ribbed roller to expel trapped air and fully saturate the weave. Respect the epoxy pot life, ambient and substrate temperature and overlap lengths given in the Sika method statement, and detail anchorage at the fabric ends so the laminate does not peel before it yields. Where the finished FRP is exposed to sunlight or needs fire or cosmetic protection, overcoat it with an appropriate Sikagard system.
Specifications
| Fibre type & orientation | Unidirectional carbon fibre, 0 degrees (96% carbon, 4% fleece/stitch) |
| Area density | 865 g/m2 +/- 45 g/m2 (carbon fibres only) |
| Dry fibre thickness | 0.478 mm (based on fibre content) |
| Dry fibre tensile strength | 3,800 N/mm2 (ASTM D 4018) |
| Dry fibre modulus of elasticity | 242,000 N/mm2 (ASTM D 4018) |
| Elongation at break | 1.43% (ASTM D 4018) |
| Laminate tensile resistance | 1,147 N/mm width (characteristic); ~1,434 N/mm average |
| Roll size & packing | 300 mm wide, roll length >= 30 m, 2 rolls per box |
| Consumption | Primer 0.6-0.8 kg/m2 (Sikadur-330); fabric layer 1.0 kg/m2 (Sikadur-300) |
Industry use cases
Seismic retrofit
Column jacketing to boost axial capacity and ductility, and masonry wall strengthening, on buildings being brought up to current seismic codes.
Infrastructure & bridges
Flexural and shear upgrades to bridge girders and RC decks carrying heavier or revised load classes without replacing the structure.
Industrial & commercial buildings
Strengthening beams and slabs for mezzanines, added storeys, new plant loads or a change of occupancy.
Repair & rehabilitation
Restoring capacity to members weakened by corrosion, overloading or original construction defects as part of a durability-driven refurbishment.
Marine & aggressive exposure
Confining and strengthening piles and coastal RC elements where a lightweight, corrosion-immune reinforcement is preferred over added steel.
Frequently asked questions
What makes SikaWrap-900 C different from a standard 300 C carbon wrap?
Can I use the fabric with any epoxy resin?
How much resin do I need per square metre?
What condition does the concrete need to be in?
Which codes does the system reference?
Does the finished carbon laminate need protecting?
How we position Sika SikaWrap-900 C
SikaWrap-900 C is the heavy end of Sika’s carbon fabric range: choose it when the strengthening demand is high and you want to minimise the number of plies. For lighter or more moderate strengthening, the same wet-layup system runs with SikaWrap-300 C or SikaWrap-231 C, and both use the same Sikadur-330 primer and Sikadur-300 (or Sikadur-330 as saturant) resins — so specifying across the range keeps one method statement on site. Where a pre-cured, factory-controlled solution suits the geometry better, Sika’s Sika CarboDur pultruded CFRP plates with Sikadur-30 adhesive are the plate-bonding alternative to fabric. Space Arc supplies and applies all of these. Across brands, we also carry Fosroc’s Nitowrap CFRP system as an equivalent EBR route where a project is standardised on Fosroc, and MC-Bauchemie’s strengthening line for consultants who specify it — we can quote and install whichever system the design is written around.
Related Structural Strengthening products
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