Sika Sikadur-330 IN
Two-part thixotropic epoxy saturant that impregnates SikaWrap fabrics and bonds them to concrete for external FRP strengthening.
What is it?
A 2-part, thixotropic epoxy impregnating and laminating resin that saturates SikaWrap carbon and glass fabrics for structural strengthening.
Where is it used?
Retrofit and seismic upgrade of RCC beams, columns, slabs and bridge members where external FRP reinforcement is specified.
Why use it?
It acts as primer and saturant in one, holds on vertical and overhead surfaces without slumping, and develops a strong, high-modulus bond to concrete.
How is it applied?
Mix Part A and Part B 4:1 by weight, apply to the prepared substrate by trowel and impregnation roller, then lay in and consolidate the fabric within the open time.
About Sika Sikadur-330 IN
Sikadur-330 IN is the epoxy resin that does the actual work in a dry-applied SikaWrap strengthening system. It is a two-component, thixotropic, high-modulus epoxy formulated for manual saturation: you prime the concrete with it, lay the carbon or glass fabric into the wet resin, and roll it through so the fibres are fully wetted out and locked to the structure. Once cured, the fabric and resin behave as a composite laminate that adds tensile capacity exactly where the existing member is deficient, whether that is flexural steel shortage in a beam soffit, shear demand across a web, or confinement of an overloaded column. Because the resin is paste-like rather than runny, it stays put on soffits and overhead faces long enough to place the fabric cleanly.
For engineers and applicators in India, the appeal is that one product covers two roles, so there is no separate primer to schedule or store, and the long pot life and open time give a realistic working window in Indian site conditions. It is supplied as a grey mixed paste from a white Part A and black Part B, which makes mix uniformity easy to judge by eye. Space Arc supplies Sikadur-330 IN as an authorised Sika channel partner across Delhi NCR and Pan-India, typically paired with the matching SikaWrap fabric and, where CFRP plates or NSM slots are involved, the correct companion adhesives so the whole strengthening scheme comes from one compatible family.
The technical insight
FRP strengthening works only if the load actually transfers from the concrete into the fibres, and that transfer happens entirely through the resin. Sikadur-330 IN is engineered around that job. Its thixotropy lets it be applied in a controlled 1 to 3 mm-scale film that will not sag off a beam soffit, yet it still flows under roller pressure to fully impregnate every filament of the fabric, eliminating dry spots and air voids that would otherwise become debonding initiation points. The cured resin develops a modulus of elasticity in flexure of about 2,800 N/mm2 and around 3,500 N/mm2 in tension, stiff enough to engage the fibres at low strain so the composite starts sharing load immediately rather than after the concrete has already deflected. The tensile adhesion to concrete is about 4 N/mm2, and critically the failure plane in the pull-off test is in the concrete itself, not the glue line, which is the proof engineers look for that the bond is stronger than the substrate. The trade-off built into the chemistry is temperature: it is tuned for ambient application and its service ceiling is +45 C, so it is a strengthening resin, not a high-heat structural adhesive.
Where it is used
- Impregnating and laminating resin for dry-applied SikaWrap carbon and glass fabric wrapping
- Substrate primer for the wet lay-up application method
- Flexural strengthening of RCC beam and slab soffits with bonded FRP
- Shear strengthening of beam webs using U-wraps or side-bonded fabric
- Confinement wrapping of columns to restore or increase axial and ductility capacity
- Seismic retrofit and upgrade of deficient concrete members
- Structural adhesive for bonding Sika CarboDur NSM profiles into surface slots
- Bonding of SikaWrap FX anchorage cord to develop and terminate fabric ends
Key advantages
- Combines primer and saturant in a single product, removing a separate priming step
- Thixotropic paste stays in place on vertical and overhead surfaces without slumping
- Long pot life of about 35 minutes and roughly 60 minutes open time at +30 C for realistic on-site placement
- High-modulus cure (about 2,800 N/mm2 flexural, 3,500 N/mm2 tensile) engages fibres at low strain
- Bond to concrete around 4 N/mm2 with failure occurring in the concrete, not the adhesive
- Formulated for hand application by trowel and impregnation roller with no spray plant required
- Two-tone A and B components make mix uniformity easy to verify visually
- Pre-batched 3 kg units eliminate site batching errors on the 4:1 mix ratio
Limitations & considerations
- Service temperature is capped at +45 C, so it is unsuitable for hot or fire-exposed structural duty
- Requires ambient and substrate temperatures between +10 C and +40 C during application and cure
- Substrate must be sound and dry (moisture content at or below 4%) with pull-off strength of at least 1.0 N/mm2
- Full cure takes 7 days at +30 C, and the wrap must be protected from rain for the first 24 hours
- Pot life shortens sharply as temperature rises and with larger mixed batches, demanding disciplined batch sizing
- Intended for use only by experienced FRP applicators following the Sika method statement, not general trades
Selection & best practice
Prepare the concrete first: grind or grit-blast to a sound, dry, laitance-free surface, make good any voids, and confirm the substrate gives at least 1.0 N/mm2 pull-off with moisture at or below 4%. Mix full units only, adding Part B to Part A and blending for about 3 minutes until the colour is a uniform grey with no streaks, then transfer to a clean container and mix a further minute to avoid unmixed material on the pail walls. In warm weather divide the mixed resin into smaller lots and keep components pre-conditioned around +23 C so the 35-minute pot life is not lost. Apply a coat to the substrate, place the SikaWrap fabric while the resin is still open, and roll firmly along the fibre direction to drive out air and fully wet the fabric, then apply the sealing coat. Keep the fabric placement and rolling inside the open time, protect from rain for 24 hours, and if a second layer or a coating goes on after 7 days, degrease with Sika Colma Cleaner and lightly abrade first. Always work to the project structural design and the relevant SikaWrap method statement.
Specifications
| Chemical base | Two-part epoxy resin |
| Mixing ratio (A:B) | 4 : 1 by weight |
| Colour (mixed) | Grey paste (Part A white, Part B black) |
| Density (mixed, +30 C) | ~1.3 kg/L |
| Consumption | 0.4 to 1.5 kg/m2 (fabric and substrate dependent) |
| Tensile strength | ~30 N/mm2 (EN ISO 527-2, 7 days at +30 C) |
| Flexural modulus of elasticity | ~2,800 N/mm2 (ISO 178) |
| Tensile adhesion to concrete | ~4 N/mm2, concrete failure (EN 1542) |
| Pot life / open time | ~35 min / ~60 min (100 g at +30 C) |
Industry use cases
Buildings & Seismic Retrofit
Wrapping columns for confinement and bonding fabric to beam soffits when live loads increase or seismic codes are upgraded, without adding significant dead weight.
Bridges & Infrastructure
Externally bonded CFRP to strengthen deficient girders, deck slabs and pier caps, extending service life while keeping traffic disruption low.
Industrial & Commercial
Strengthening slabs and beams for new plant loads, mezzanine additions or change of use where demolition and recasting are not viable.
Repair & Rehabilitation
Restoring capacity to members weakened by corrosion, overloading or construction defects as part of a wider concrete repair scheme.
Water & Marine Structures
Reinforcing tanks, channels and structures in damp environments, taking advantage of the resin’s moisture tolerance and strong concrete bond.
Frequently asked questions
Do I need a separate primer with Sikadur-330 IN?
What is the mixing ratio and how do I know the mix is right?
How much resin will I need per square metre?
Can Sikadur-330 IN bond CFRP plates as well?
What conditions do I need on site to apply it?
How long is the working time and full cure?
How we position Sika Sikadur-330 IN
Sikadur-330 IN is one component of a complete Sika strengthening system, so specify it alongside the matching SikaWrap carbon or glass fabric it is designed to saturate. Where the scheme calls for near-surface-mounted reinforcement, Sikadur-330 IN also bonds Sika CarboDur NSM profiles, but for bonding CarboDur plate laminates to the surface you should switch to the dedicated Sikadur-30 family plate adhesive rather than this saturant. If a project runs on the Fosroc system instead, the equivalent solution is Fosroc’s Nitowrap FRP wrapping range. For engineers weighing brands, Space Arc can supply either family and advise on the right saturant, fabric and anchorage combination for your structural design.
Fosroc Nitowrap EP(CF) — Choose the Fosroc carbon-fibre wrap system when the project is already standardised on Fosroc Nitowrap and its epoxy saturant for FRP strengthening, giving a single-brand alternative to SikaWrap with Sikadur-330 IN.
Related Structural Strengthening products
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