Sika Sikadur-32
A solvent-free, two-part epoxy that welds fresh concrete and repair mortar to hardened, prepared substrates, so overlays and patches behave as one monolithic member.
What is it?
A two-component, solvent-free epoxy resin bonding agent (base plus hardener) that primes a prepared concrete surface just before fresh concrete, screed or repair mortar is placed on top.
Where is it used?
Structural concrete repairs, bonded overlays and toppings, precast joints, bridge decks, RC slabs and beams, and anywhere new-to-old concrete continuity is critical.
Why use it?
It defeats the classic cold-joint failure: bonded interfaces develop a shear grip strong enough that any pull-off failure runs through the parent concrete, not along the joint.
How is it applied?
Mix base and hardener to the Sika-specified ratio, brush or roller a thin film onto a sound, roughened, dust-free substrate, then place the fresh concrete or mortar wet-on-wet inside the open time.
About Sika Sikadur-32
Sika Sikadur-32 belongs to the Sikadur family of structural epoxies, and its job on site is narrow but decisive: it makes new concrete stick to old concrete. When a repair mortar, a bonded topping or a fresh structural pour is placed against a hardened, cured substrate, the interface is inherently a weak plane. Without a bonding coat, that plane becomes the first thing to delaminate under shear, thermal movement or traffic. Sikadur-32 is applied as a thin epoxy film onto the prepared old surface, and the fresh material is placed while that film is still tacky, so the two ages of concrete cure into a single, continuous element instead of two layers waiting to separate.
Because it is a 100% solids, solvent-free system, there is no evaporating carrier that could leave voids or a soft skin at the joint, and no VOC odour to manage in enclosed repairs. The mixed resin cures to a hard, chemically resistant film that also doubles as a surface sealer and a moisture barrier at the interface. For engineers and applicators across Delhi NCR and the rest of India, that translates into a predictable, standards-referenced way to guarantee bond in slab overlays, beam and column repairs, precast connections and deck rehabilitation, where a failed interface would otherwise mean chasing delamination for years.
The technical insight
The reason a Sikadur-32 joint outperforms an un-primed one comes down to how epoxy bridges two dissimilar surfaces. Hardened concrete presents a porous, microscopically rough face; fresh concrete presents cement paste and water. The low-viscosity epoxy wets into the open pores of the old substrate and, before it gels, chemically keys onto the fresh cementitious matrix placed against it. Once cured, the film has a tensile and shear capacity well above the tensile strength of concrete itself, which is why pull-off tests on properly prepared, primed joints break inside the parent concrete rather than at the glue line. The practical lever the applicator controls is open time: the fresh material must go down while the film is still wet and reactive. That window depends heavily on temperature, and in Indian summer conditions it shortens sharply, so the bonding coat is deliberately applied in manageable strips rather than flooding a whole bay at once.
Where it is used
- Bonding fresh structural concrete or screed to an existing hardened, cured slab or deck
- Priming the substrate ahead of cementitious repair mortars in beam, column and slab patch repairs
- Bonded overlays and toppings on floors, ramps and bridge decks where interface shear is critical
- Connecting precast concrete units and stitching new construction to old at construction joints
- Sealing and priming prepared concrete before placing repair material in spalled or corroded RC zones
- Grouting-adjacent repairs where a monolithic new-to-old bond is required under load
- Retaining wall and water-retaining structure repairs needing a durable, sealed interface
- Establishing a moisture and chemical barrier at the joint in aggressive or wet exposures
Key advantages
- Solvent-free, 100% solids formulation that cures without shrinkage voids or a soft interface skin
- Creates a bond stronger than the concrete substrate, so failures run through the parent material, not the joint
- Low viscosity lets the resin wet into surface pores for a deep mechanical and chemical key
- Simple brush or roller application by trained site crews, no specialist plant required
- Doubles as a surface sealer and moisture barrier at the new-to-old interface
- Good chemical resistance once cured, suiting industrial and aggressive-exposure repairs
- References EN 1504-4 structural bonding, giving specifiers a recognised compliance anchor
- Long shelf life in sealed packs makes it practical to stock for phased repair programmes
Limitations & considerations
- Open time is temperature-sensitive and drops steeply in Indian summer heat, so fresh material must follow the coat quickly
- Wet-on-wet discipline is essential; if the film skins over before placement, the bond is compromised and the area must be recoated
- Bond is only as good as the preparation, requiring a sound, roughened, laitance-free and dust-free substrate
- Not a substitute for the repair mortar or structural pour itself; it is strictly an interface bonding coat
- Sensitive to moisture and low temperature during application and early cure; cold, damp conditions slow or impair curing
- Two-component mixing must follow the specified ratio precisely, as off-ratio mixes may never fully cure
Selection & best practice
Success is decided at the substrate, not in the tin. Mechanically prepare the old concrete to remove laitance, dust and any loose or unsound material, exposing a roughened, structurally sound face, and blow or vacuum it clean. Mix the base and hardener thoroughly in the full Sika-specified proportion until uniform in colour, using a slow-speed paddle to avoid entraining air. Brush or roller a continuous, thin film only over the area you can realistically cover with fresh concrete or mortar before the open time expires, and in hot weather work in small strips rather than a whole bay. Place the repair material wet-on-wet while the film is still tacky. If any coated area skins over or dries before placement, do not proceed over it, abrade and recoat that patch. Protect freshly bonded work from rain, standing water and direct summer sun during early cure, and always confirm ratios, open time and consumption against the current Sika India Technical Data Sheet for the exact grade supplied.
Specifications
| Type | Two-component, solvent-free epoxy resin bonding agent |
| Components | Base (Part A) + Hardener (Part B), pre-proportioned |
| Mixed colour | Concrete grey |
| Mixed density | approx. 1.4 ± 0.1 kg/litre at +23°C |
| Compressive strength | approx. 65 N/mm² (7 days at +30°C) |
| Bond strength to concrete | 2.5 – 3 N/mm² (concrete failure) |
| Consumption / coverage | approx. 0.3 – 0.8 kg/m² depending on substrate texture |
| Standard referenced | EN 1504-4 (structural bonding of concrete) |
| Shelf life / storage | 24 months in sealed packs, stored dry at +5°C to +30°C |
Industry use cases
Bridge & Infrastructure
Bonding new overlays and topping layers to existing bridge decks and RC members so rehabilitated sections carry traffic and thermal loads as one monolithic unit.
Industrial & Commercial Buildings
Priming old slabs before bonded screeds and repair mortars in floors, ramps and loading areas where delamination under wheel loads is unacceptable.
Water-Retaining & Marine Structures
Sealing and bonding repairs in tanks, retaining walls and wet-exposure structures, adding a durable moisture and chemical barrier at the interface.
Precast & New Construction
Stitching precast units and connecting fresh pours to hardened concrete at construction joints, ensuring structural continuity across the interface.
Structural Repair & Retrofit
Beam, column and slab patch repairs where a corroded or spalled zone must be rebuilt with mortar bonded permanently to the sound parent concrete.
Frequently asked questions
What exactly is Sikadur-32 used for?
How much area does one unit cover?
Why does the bond fail through the concrete and not at the glue line?
How long do I have to place the fresh material after coating?
How do I prepare the surface before applying it?
Is there a Fosroc equivalent if my specification calls for one?
How we position Sika Sikadur-32
Sikadur-32 sits within Sika’s structural repair and bonding line and pairs naturally with the rest of the Sika system on a repair: Sika MonoTop and SikaTop repair mortars for the reinstatement itself, Sikadur structural epoxy adhesives and grouts (such as the Sikadur-31 family) where a thixotropic paste rather than a brushable coat is needed, and Sikagard protective coatings to seal the finished repair. Where a project runs on a Fosroc specification instead, the equivalent workflow is Fosroc Nitobond EP as the bonding coat with Fosroc Renderoc mortars, and for cementitious rather than epoxy bonding we also stock latex-modified SBR bonding agents from Sika, Fosroc and Dr. Fixit. As an authorised distributor for multiple brands, Space Arc supplies whichever family your consultant has specified rather than pushing a single line.
Fosroc Nitobond EP — Choose the Fosroc option when the project is specified around the Fosroc Renderoc repair system or the approved-vendor list names Fosroc, since Nitobond EP is the like-for-like solvent-free epoxy bonding coat for that workflow.
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Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.