Sika Sikadur-41 IN
A three-part thixotropic epoxy mortar that patches spalled concrete on vertical and overhead surfaces without slumping, shuttering or shrinkage.
What is it?
A solvent-free, three-component thixotropic epoxy mortar (resin, hardener and graded quartz filler) that mixes into a stiff, trowellable repair and bonding paste for concrete, stone and masonry.
Where is it used?
Spalled beam soffits, column heads, stair nosings, cavities and honeycombing on vertical and overhead surfaces, plus bearing pads for bridges and heavy machinery.
Why use it?
It stays put on soffits and walls without formwork, cures without shrinkage and develops very high mechanical strength, so a small local repair is done in one visit.
How is it applied?
Prepare a sound, clean, dry-to-mat-damp substrate; mix A+B then add C; brush it well into the surface and trowel in layers up to 30 mm, smoothing off with a steel trowel.
About Sika Sikadur-41 IN
Sikadur-41 IN is Sika’s workhorse epoxy patching mortar for the kind of concrete damage that ordinary cementitious repair struggles with: spalls and cavities on faces you cannot lay a mortar flat onto. It arrives as three pre-batched parts — a white resin paste (A), a black hardener paste (B) and a sand-coloured quartz filler (C) — which combine into a concrete-grey mortar with a genuinely thixotropic body. That means it holds its shape at rest and only flows under the trowel, so it can be built onto a soffit or column face and it stays there while it cures, with no formwork and no sagging up to 20 mm of layer thickness.
For engineers and applicators in Delhi NCR and across India, the appeal is the combination of strength and convenience. The mortar reaches roughly 65 N/mm2 in a single day and over 80 N/mm2 by 14 days, bonds to the parent concrete strongly enough that pull-off tests fail in the concrete rather than at the interface, and needs no primer on a sound dry surface. It is solvent-free and comes in colour-differentiated parts so the site team can see when the mix is homogeneous. Space Arc Engineering supplies Sikadur-41 IN as an authorised Sika distributor in the 6 kg and 60 kg pre-batched units, with technical support on substrate assessment, primer selection and detailing for your specific repair.
The technical insight
The behaviour that defines this product is thixotropy engineered into an epoxy matrix. The quartz aggregate and the resin system are balanced so the fresh mortar has a high yield stress at rest but shear-thins when worked — it will not slump on a vertical or overhead face yet spreads cleanly under a trowel. Strength comes from the crosslinked epoxy binder rather than cement hydration, which is why it gains load-bearing capacity in hours instead of days and cures with essentially no drying shrinkage. Because there is no water of hydration, the mortar can be placed on a mat-damp (not wet) substrate when the epoxy primer is brushed well in, and the same chemistry gives the high abrasion and chemical resistance that lets it double as a protective wearing layer. One property to design around: like all polymers, cured epoxy creeps under sustained load, so Sika recommends keeping long-term structural design load below roughly 20-25% of the failure load rather than treating the short-term strength figures as a permanent working stress.
Where it is used
- Reinstating spalled and delaminated concrete on beam soffits, column heads and slab undersides
- Vertical and overhead filling of cavities, blowholes and honeycombing without shuttering
- Rebuilding damaged stair nosings, arrises, edges and corners
- Bonding mortar for stone, concrete, mortar and plaster work
- Abrasion-resistant protective screed or wearing layer on localised concrete
- Bedding and bearing pads for bridge components and heavy machinery
- Localised structural repair where high early and ultimate strength is required
- Patch repair in chemically or mechanically aggressive plant environments
Key advantages
- Thixotropic, non-sag body holds on vertical and overhead work up to 20 mm per pass — no formwork
- Very high strength: 65 N/mm2 at 1 day rising above 80 N/mm2 by 14 days
- Tensile adhesion so strong that pull-off failure occurs in the concrete, not the bond line
- Hardens without shrinkage, so repairs stay tight to the parent substrate
- No primer needed on a sound, dry surface, which speeds up straightforward repairs
- Colour-differentiated parts give a clear visual check that mixing is complete
- Solvent-free with good abrasion and chemical resistance for a durable patch
- Pre-batched 6 kg and 60 kg units remove site batching error
Limitations & considerations
- For experienced professionals only — mix control and pot-life management matter
- Short pot life of about 30 minutes at +30°C, and even shorter as temperature rises
- Maximum 30 mm per layer; deeper build-ups must be applied in successive cured layers
- Cannot be placed below +10°C ambient or substrate temperature, or over standing water
- Epoxy creeps under sustained load, so long-term design load must stay well below failure load
- Higher material cost than cementitious repair mortars, so best reserved for demanding local repairs
Selection & best practice
Work to the pot life, not the clock on the wall. Because roughly 30 minutes is all you get at +30°C — and less in a Delhi summer — mix only what the crew can place, and in hot weather either split the mixed batch into smaller portions or pre-chill parts A+B and C (not below +5°C) to buy workability. Confirm the concrete is older than 28 days and mechanically prepared to a sound, laitance-free, open texture by grit-blasting or equivalent. On a sound dry surface no primer is needed; on a mat-damp surface brush Sikadur-31 IN well in and place the mortar while the primer is still tacky. Mix A+B for at least 3 minutes with a slow drill (max 300 rpm) to a uniform grey, add C to homogeneity, then decant and stir a further minute to knock out entrained air. Brush the first pass firmly into the substrate for intimate contact, build in layers not exceeding 30 mm, and finish with a clean steel trowel. Clean tools with Sika Colma Cleaner immediately — once cured it only comes off mechanically.
Specifications
| Chemical base | Solvent-free 3-component epoxy resin with graded quartz aggregate |
| Mixing ratio (A:B:C) | 2 : 1 : 3 by weight |
| Density (mixed) | 2.00 ± 0.05 kg/litre at +27°C |
| Compressive strength | ≥ 65 N/mm2 (1 day), ≥ 70 (7 days), ≥ 80 (14 days) at +30°C, ASTM C 579 |
| Tensile strength in flexure | ≥ 25 N/mm2 at 14 days, +30°C (EN 196) |
| Tensile adhesion strength | ≥ 10 N/mm2, concrete failure, 7 days at +30°C (ASTM C 882) |
| Pot life | ~30 minutes (100 g mass at +30°C) |
| Layer thickness / sag | 30 mm max per layer; non-sag up to 20 mm on vertical surfaces |
| Consumption | ~2 kg per m² per mm of thickness |
Industry use cases
Bridges & Infrastructure
Reinstating spalled soffits and pier caps overhead, and forming durable bearing pads for bridge components, without erecting formwork over traffic or water.
Industrial & Chemical Plants
Localised patch repair of floors, plinths and columns in abrasive or chemically aggressive areas where a solvent-free, high-strength epoxy patch is preferred.
Commercial & Residential Buildings
Fixing spalled beam and slab undersides, honeycombing and damaged stair nosings during structural rehabilitation and facade repair.
Marine & Water-Retaining Structures
Reinstating aggressive-exposure concrete on jetties, tanks and channels where high bond strength and shrinkage-free curing are essential.
Precast & Machine Foundations
Edge and arris repair on precast units and abrasion-resistant bedding for heavy machinery bases needing rapid, high strength.
Frequently asked questions
Does Sikadur-41 IN need a primer?
How thick can I apply it in one go?
What is the pot life and how do I manage it in Indian summers?
How much material will I need?
How strong is it and how fast does it gain strength?
How is it different from a cementitious repair mortar?
How we position Sika Sikadur-41 IN
Within the Sika family, pair Sikadur-41 IN with Sikadur-31 IN as the epoxy primer for damp substrates, and reach for Sika MonoTop or SikaRep cementitious mortars when the job is large-area resurfacing rather than a high-strength local patch; use Sika Colma Cleaner for tool cleaning. Across the brands Space Arc distributes, Fosroc, Dr. Fixit, MC-Bauchemie and Master Builders Solutions all offer comparable epoxy and cementitious repair systems, so we match the product to the exposure, depth and budget of each repair rather than pushing a single line.
Fosroc Nitomortar HB — A specifier standardised on Fosroc, or one wanting a lightweight high-build epoxy that can be trowelled thickly onto soffits and walls in one pass, may prefer Nitomortar HB for the same non-sag vertical and overhead repair role.
Related Concrete Repair products
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Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.