Sika Sikadur-32 IN
A solvent-free, moisture-tolerant epoxy that bonds fresh concrete, mortar and steel to hardened substrates with a joint stronger than the concrete itself.
What is it?
A two-component, solvent-free epoxy resin bonding agent (ASTM C 881-78, Type II, Grade 2, Class B+C) used as a structural bridge between old and new concrete.
Where is it used?
Concrete repair and rehabilitation work: bonding fresh concrete, screeds and repair mortars onto cured substrates, plus steel-to-concrete connections on bridges, floors, columns and beams.
Why use it?
It develops an adhesion far exceeding the tensile strength of the parent concrete, works on damp surfaces, and cures without shrinkage, so the cold joint does not become the weak point.
How is it applied?
Mix Part A and B at 2:1 by weight for 3-4 minutes, brush or roller the light-grey adhesive onto the prepared substrate, then place the new concrete or mortar while the coat is still tacky.
About Sika Sikadur-32 IN
Every time you pour fresh concrete or trowel a repair mortar against an existing surface, you create a cold joint, and that joint is usually the first thing to fail. Sikadur-32 IN exists to remove that weakness. It is a solvent-free, two-part epoxy resin adhesive from Sika that you apply to the prepared old surface immediately before placing the new material, so the two set together as one monolithic mass rather than two layers pressed against each other. Because it is engineered to develop a bond stronger than the tensile capacity of the concrete around it, the failure plane shifts away from the interface and into the substrate itself, which is exactly what a structural engineer wants to see. | For Indian sites, its most valuable trait is that it is genuinely moisture-insensitive. Foundations, bridge soffits, water-retaining structures and monsoon-season repairs are rarely bone dry, and most bonding agents lose grip on a damp substrate. Sikadur-32 IN keeps working on matt-damp concrete as long as the adhesive is brushed firmly into the pores. It carries an ASTM C 881-78 classification (Type II, Grade 2, Class B+C), cures without shrinkage, and remains workable even at lower temperatures, making it a dependable choice for the demanding, unpredictable conditions of a live repair job across Delhi NCR and Pan-India projects.
The technical insight
The performance comes from the epoxy chemistry itself. When Part A (the resin, supplied white) and Part B (the hardener, black) are combined at a 2:1 ratio by weight, they cross-link into a dense, rigid thermoset with a mixed density of about 1.55 kg/L and no solvent to evaporate, which is why it cures without the shrinkage that plagues solvent-based or cementitious slurries. That absence of shrinkage matters: a bonding layer that pulls away as it dries defeats its own purpose. The cured film reaches a tensile adhesion of at least 10 N/mm on dry concrete, comfortably above the roughly 2-3 N/mm tensile strength of typical structural concrete, so any pull on the joint is resisted by the parent material long before the glue line gives way. Being moisture-tolerant, the resin displaces the thin film of water in a damp pore and still wets the surface, provided you brush it in rather than merely lay it on. The one discipline the mechanism demands is timing: the new concrete must be placed while the epoxy is still tacky and within its open time, because once it skins over, it becomes a bond breaker instead of a bond builder.
Where it is used
- Bonding freshly placed concrete or repair mortar to hardened, cured concrete
- Structural repair of bridge decks, soffits and abutments where a monolithic joint is required
- Anchoring new cementitious overlays, screeds and toppings onto old industrial floor slabs
- Reinstating columns, beams and other load-bearing members with fresh concrete or mortar
- Bonding steel and iron sections onto a concrete substrate in strengthening work
- Cold-joint treatment in staged or interrupted concrete pours
- Repairs on damp or matt-moist substrates where cementitious bonding slurries fail
- Precast-to-in-situ connections requiring a high-strength structural bond
Key advantages
- Develops a bond stronger than the tensile strength of the concrete itself, so failure moves into the substrate, not the joint
- Moisture-insensitive: performs on damp and matt-moist surfaces, ideal for foundations, water structures and monsoon repairs
- Solvent-free with low odour, suitable for enclosed and poorly ventilated repair areas
- Cures without shrinkage, keeping the bond line intact as it hardens
- Pre-batched 2:1 packs remove site guesswork and reduce mixing errors
- Remains workable at lower temperatures where many epoxies stiffen
- Bonds a wide range of substrates including concrete, mortar, steel and iron
- Backed by ASTM C 881-78 (Type II, Grade 2, Class B+C) classification for specification confidence
Limitations & considerations
- Strictly a bonding primer, not a repair mortar or filler; it must be paired with a suitable concrete or Sika repair mortar to rebuild section
- Has a limited open time (around 55 minutes at 27 degrees C), so the new concrete must be placed while the coat is still tacky or the bond is lost
- For professional use only; correct surface preparation and firm brushing into the substrate are essential to results
- Substrate must be sound, over 28 days old, mechanically roughened and free of laitance, oil, standing water and loose particles
- Pot life shortens sharply in hot weather and with larger mixed quantities, demanding careful batch planning on site
- Being a rigid epoxy, it is a structural bonding layer and is not a substitute for a flexible sealant at moving joints
Selection & best practice
Preparation decides the outcome. Mechanically roughen the old concrete to expose a sound, open-textured surface, then remove all laitance, dust, oil, curing compound and loose particles; the substrate should be over 28 days old and free of standing water and frost. Combine Part A and Part B at 2:1 by weight and mix for at least three minutes with a slow-speed drill (max 600 rpm) until the colour is a uniform light grey, avoiding air entrainment, then decant and stir once more. Brush or roller the adhesive onto the prepared surface, and on damp concrete work it firmly into the pores rather than flood-coating. Critically, place your fresh concrete or repair mortar while the epoxy is still wet and tacky and within its open time; if it skins over, remove it and reapply. Mix only what you can use within the pot life, chill the components in hot weather to buy working time, and clean tools with Sika Colma Cleaner before the resin hardens.
Specifications
| Chemical base | Two-component, solvent-free epoxy resin |
| Standard | ASTM C 881-78, Type II, Grade 2, Class B+C |
| Mixing ratio (A:B) | 2 : 1 by weight |
| Colour | Part A white, Part B black, mixed light grey |
| Density (mixed) | 1.55 ± 0.05 kg/L at +27 degrees C |
| Consumption | 0.3 – 0.8 kg/m2, depending on substrate |
| Pot life | 55 min (100 g at +27 degrees C) |
| Compressive strength | ≥15 N/mm2 at 1 day; ≥40 N/mm2 at 7 days (ASTM C579) |
| Tensile adhesion strength | ≥10 N/mm2 on dry concrete (14 days, ASTM C882) |
| Packaging / shelf life | 3 kg pre-batched set (2 kg A + 1 kg B); 12 months |
Industry use cases
Bridges & Infrastructure
Bonding new concrete to old on deck repairs, soffits and pier reinstatement, where the moisture tolerance handles damp, exposed structures and the high adhesion restores monolithic behaviour.
Industrial Flooring
Keying new toppings, screeds and patch repairs onto worn factory and warehouse slabs so the overlay does not delaminate under traffic and point loads.
Water-Retaining Structures
Repairing tanks, sumps, STPs and reservoirs where the substrate is rarely dry; the moisture-insensitive epoxy bonds where cementitious slurries would fail.
Building Repair & Rehabilitation
Reinstating spalled columns, beams and slabs with fresh mortar or micro-concrete, giving the repair a structural bond back into the parent member.
Precast & Structural Steel
Joining precast elements to in-situ concrete and bonding steel or iron sections onto concrete during strengthening and connection work.
Frequently asked questions
Can Sikadur-32 IN be applied to a damp concrete surface?
Is Sikadur-32 IN a repair mortar I can use to fill a spall?
How much do I need per square metre?
How long do I have to place the new concrete after applying it?
What is the mixing ratio and how should it be mixed?
Does Space Arc supply Sikadur-32 IN across India with technical support?
How we position Sika Sikadur-32 IN
Sikadur-32 IN is the bonding primer within the wider Sika concrete-repair system: it is designed to work hand in hand with Sika’s epoxy and cementitious repair mortars, which supply the actual patch material once the bond coat is down, and its tools are cleaned with Sika Colma Cleaner. Where a project needs a lower-viscosity or long-pot-life variant, the Sikadur-32 LP IN grade is worth discussing. If a specification is written around the Fosroc range rather than Sika, the closest equivalent from our other brands is Fosroc Nitobond EP, a comparable two-component solvent-free epoxy bonding agent. Talk to Space Arc and we will match the bonding agent, the repair mortar and, where movement is expected at the joint, the correct sealant, so the whole repair build-up comes from one compatible family.
Fosroc Nitobond EP — A specifier standardised on the Fosroc Renderoc repair system would pick Nitobond EP, the directly equivalent two-component solvent-free epoxy bonding agent, to keep the bond coat and repair mortar within one compatible product family.
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Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.