Sika Sikadur-30 LP IN
A long-pot-life, non-sag epoxy adhesive that keeps CFRP and steel plate bonding reliable even when the ambient and substrate temperatures climb toward +55°C.
What is it?
A two-part, thixotropic epoxy paste adhesive (Part A : Part B = 3 : 1 by weight) formulated with a deliberately extended pot life for structural plate bonding.
Where is it used?
Externally bonded reinforcement on concrete bridges, beams, slabs and columns, plus steel plate bonding, in warm and hot site conditions from +25°C to +55°C.
Why use it?
Its slow-reacting chemistry gives crews a workable window in Indian summer heat where standard Sikadur-30 would gel too fast, without sagging in vertical or overhead positions.
How is it applied?
Mixed on site to a uniform grey, then trowelled onto both the prepared substrate and the CFRP laminate or steel plate before the plate is pressed home and excess adhesive struck off.
About Sika Sikadur-30 LP IN
Sikadur-30 LP IN belongs to Sika’s structural strengthening range and does one job exceptionally well: it glues externally bonded reinforcement to a structure so the two act as one. The “LP” tag stands for long pot life, and that single letter is the whole point of the product. Standard Sikadur-30 is engineered for a comfortable +8°C to +35°C. On an exposed Indian bridge deck or a rooftop transfer beam in May, surface temperatures routinely push past +45°C, and a normal epoxy would start to gel before a crew has finished buttering a three-metre plate. This LP grade shifts the whole working envelope upward, staying trowellable and non-sag between +25°C and +55°C.
Chemically it is a two-component system based on epoxy resins and special fillers, supplied in a pre-batched 6 kg unit (4.5 kg of Part A resin plus 1.5 kg of Part B hardener) so there is no site guesswork on the 3:1 ratio. Once mixed it behaves like a stiff, buttery paste: it clings to overhead and vertical faces, cures without shrinkage, and is unaffected by high ambient humidity. For engineers, it is the bonding layer that lets a Sika CarboDur laminate or a steel plate transfer real load into an existing beam, and it works to the European strengthening standard EN 1504-9 (Principle 4, structural strengthening).
The technical insight
The reason plate bonding works at all is shear transfer: the load a strengthening plate is supposed to carry has to pass through a paper-thin glue line into the parent concrete or steel. That glue line therefore has to be stiff, strong and creep-resistant, because it is under permanent load for the life of the structure. Sikadur-30 LP IN is built around this. It develops a modulus of elasticity of roughly 10,000 N/mm², so it is rigid enough to move load into the substrate rather than deforming under it, yet its tensile adhesion to steel exceeds 18 N/mm² at +25°C. The clever part is the hardener chemistry: it is formulated to react more slowly, so the exotherm and gel point are pushed back. That buys about 60 minutes of pot life per 100 g at +25°C and still around 30 minutes at +55°C, with an open time of roughly 80 and 50 minutes respectively. In practice that means a crew keeps a usable, non-sagging bond line long enough to position a large plate accurately in the heat, and the cured adhesive still delivers the stiffness the design engineer assumed.
Where it is used
- Flexural strengthening of bridge girders and deck beams by bonding CFRP laminates to soffits
- Shear strengthening of beams and the uprating of floor slabs and transfer beams for higher loads
- Bonding steel plates to concrete on bridges, car-park decks and warehouse floors
- Seismic retrofit of columns and beams where external reinforcement is added to existing frames
- Change-of-use projects where a slab or beam must carry heavier machinery or storage loads
- Bonding Sika CarboDur pultruded CFRP plates as externally bonded reinforcement
- Structural repair schemes executed under EN 1504-9 Principle 4 (structural strengthening)
- Hot-climate and summer-season strengthening where standard plate-bonding epoxies gel too quickly
Key advantages
- Extended pot life keeps the adhesive workable in warm and hot conditions up to +55°C substrate and ambient
- Thixotropic, non-sag consistency holds on vertical and overhead surfaces without slumping
- High creep resistance under permanent load, essential for a bond line that is stressed for decades
- Cures without shrinkage and is not affected by high ambient humidity during application
- Strong, stiff bond: tensile adhesion to steel above 18 N/mm² and a modulus around 10,000 N/mm²
- Bonds a wide range of substrates including concrete, masonry, steel, cast iron, aluminium and timber
- No primer required, and the pre-batched 3:1 unit removes on-site mixing errors
- Impermeable to liquids and water vapour, protecting the bonded interface
Limitations & considerations
- Designed specifically for elevated temperatures (+25°C to +55°C); in cooler conditions the standard Sikadur-30 grade is the correct choice
- Maximum adhesive layer thickness is 30 mm, so it is a bonding paste, not a gap-filling or levelling mortar
- Substrate must be sound and clean; concrete pull-off strength is critical, and low-strength concrete may need an alternative such as a fabric wrap
- Cured mechanical performance and full strength are quoted at 7 days, so structures cannot be loaded immediately after bonding
- Larger mixed masses shorten the pot life through self-heating, so batch sizes must be planned for the deck temperature
- As a structural adhesive it demands trained applicators and correct surface preparation; it is not a general-purpose glue
Selection & best practice
Prepare the substrate first: concrete should be gritblasted or ground to expose sound aggregate, and steel should be blasted to near-white metal, both dry and dust-free. Because pot life shortens as temperature and batch size rise, mix only what the crew can place within the window and keep unopened units shaded, not baking in the sun. Stir Part A and Part B thoroughly until the grey is uniform with no streaks, then apply the adhesive to both the prepared substrate and the plate, forming a slight roof-ridge profile on the plate so air is squeezed out when it is pressed home. Press the plate firmly with a rubber roller until adhesive is forced out along both edges, strike off the excess, and leave the bond undisturbed to cure. Confirm the finished bond and substrate quality with pull-off testing where the specification calls for it.
Specifications
| Product type | Two-component thixotropic epoxy adhesive (long pot life) |
| Mixing ratio | Part A : Part B = 3 : 1 by weight |
| Pack size | 6 kg pre-batched unit (4.5 kg Part A + 1.5 kg Part B) |
| Application temperature | +25°C to +55°C (ambient and substrate) |
| Pot life (per 100 g) | approx. 60 min at +25°C; approx. 30 min at +55°C |
| Compressive strength (7 days) | approx. 85 N/mm² at +25°C; approx. 90 N/mm² at +55°C |
| Modulus of elasticity | approx. 10,000 N/mm² at +25°C |
| Tensile adhesion to steel (3 days) | ≥18 N/mm² at +25°C; ≥20 N/mm² at +55°C |
| Maximum layer thickness | 30 mm |
Industry use cases
Bridges & Infrastructure
Bonding CFRP laminates and steel plates to girders and decks to raise load ratings, carried out in hot, exposed field conditions where a long working time is decisive.
Commercial & Industrial Floors
Strengthening car-park decks, warehouse slabs and transfer beams so they can carry heavier storage, racking or plant loads without demolition.
Seismic Retrofit
Adding externally bonded reinforcement to columns and beams of existing frames to improve ductility and capacity ahead of code upgrades.
Change-of-Use & Refurbishment
Uprating slabs and beams in buildings being repurposed for heavier occupancy or new equipment, using plate bonding rather than replacement.
Heritage & Masonry
Bonding reinforcement to stonework and brick members where load must be added discreetly without adding significant dead weight.
Frequently asked questions
What is the difference between Sikadur-30 and Sikadur-30 LP IN?
How long is the pot life, and does the heat shorten it?
Do I need a primer before applying it?
Which plates and substrates does it bond?
What is the coverage from one 6 kg unit?
Can Space Arc supply it with application support in Delhi NCR and pan-India?
How we position Sika Sikadur-30 LP IN
Sikadur-30 LP IN is the hot-weather member of Sika’s plate-bonding range; for cooler sites the standard Sikadur-30 grade is the correct pick, so specifiers should choose by expected deck temperature. It is designed to work hand-in-hand with Sika CarboDur pultruded CFRP laminates, and where concrete pull-off strength is marginal or geometry is curved, a wet-layup fabric such as SikaWrap is the better strengthening route than rigid plates. Across our other brands, Fosroc offers a parallel carbon-fibre strengthening line, so for projects standardised on Fosroc materials we can supply an equivalent system rather than mixing brands on one structure. Talk to our technical team and we will match the adhesive, laminate or fabric to your load case and site conditions.
Fosroc Nitowrap EP(CF) Carbon Fibre Wrap — When a project is standardised on Fosroc materials or the member is curved or has marginal concrete, a specifier may prefer this wet-layup carbon-fibre fabric system over rigid plate bonding to reach the same strengthening outcome.
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