Fosroc Nitobond EP03-IM
Solvent-free, two-component epoxy-resin bonding agent that welds fresh concrete, screeds and repair mortars to existing cementitious substrates — with adhesion that exceeds the tensile strength of the host concrete.
What is it?
A solvent-free, two-component (base + hardener) epoxy-resin bonding agent in the Fosroc Nitobond EP03 family. It is brush- or roller-applied to a prepared substrate so that freshly placed concrete, screed or repair mortar bonds monolithically to the old surface instead of forming a cold, debonding joint.
Where is it used?
Old-to-new concrete junctions on roads, bridges, flyovers, pavements, loading bays, factory floors and industrial repairs — wherever a structural bond between hardened and fresh cementitious material is required, internally or externally.
Why use it?
It develops positive adhesion that exceeds the tensile strength of the parent concrete, tolerates dry or damp substrates, and offers a long open/overlay time that suits hot Indian site conditions and lets crews fix reinforcement and formwork before placing concrete.
How is it applied?
Prepare and roughen the substrate, mix the differentially pigmented base and hardener to a uniform colour, apply an unbroken film by brush or roller, then place the new concrete or mortar while the film is still tacky (never after it has hardened).
About Fosroc Nitobond EP03-IM
Fosroc Nitobond EP03-IM is a high-performance epoxy-resin concrete bonding agent that belongs to Fosroc’s well-established Nitobond EP / EP03 range. In concrete repair and rehabilitation, the weakest point is almost always the interface between the old, hardened concrete and whatever new material is placed against it — a screed, a structural overlay, or a patch repair. Left untreated, that junction behaves as a cold joint: it debonds under load, lets water track through, and becomes the first place the repair fails. Nitobond EP03-IM is engineered to eliminate that cold joint by chemically welding the two layers into a monolithic whole.
The product is a two-component, solvent-free epoxy system supplied as a pre-weighed base and hardener. The base is white and the hardener is green, so the moment the two are blended to a uniform colour the applicator has unmistakable visual proof that mixing is complete — a small but genuinely useful site-level safeguard against under-mixed, under-cured material. Because it is 100% solids and solvent-free, it can be used safely in enclosed and poorly ventilated locations such as basements, water-retaining structures, tanks and tunnels, where solvent-based primers would be a fire and inhalation hazard.
What sets the EP03 family apart from a fast-setting epoxy primer is its deliberately long “open” or overlay time. On a busy Indian site, a contractor often needs hours — not minutes — to position reinforcement cages, erect formwork and get the concrete pump or mortar batch ready after the bonding coat goes down. Nitobond EP03-IM’s slow, controlled cure gives that working window even at elevated temperatures, which is precisely why Fosroc positions this grade for high-temperature working and projects with heavy formwork and rebar fitment.
The “IM” suffix denotes the specific regional/market designation Fosroc uses for this grade; the underlying chemistry, use profile and performance class are those of the Nitobond EP03 epoxy bonding agent, which complies with ASTM C881 — the recognised standard for epoxy-resin bonding systems for concrete.
The technical insight
The defining technical property of Nitobond EP03-IM is that its bond strength exceeds the tensile strength of the host concrete — meaning that in a correctly executed application, a pull-off failure will occur within the parent concrete rather than at the glue line. That is the gold standard for a structural bonding agent and the reason it is specified for load-bearing repairs rather than cosmetic ones. The chemistry behind this is a solvent-free, two-component epoxy with no shrinkage on cure (unlike solvent-based or polymer-emulsion primers that lose volume as the carrier evaporates), so the film stays in intimate, gap-free contact with both substrates. The other engineering subtlety is the overlay-time window: the bonding coat must be placed against fresh concrete while it is still TACKY but not wet. Place too early and the bond film has no integrity; place after it has gone hard and you have created a slip plane instead of a bond — the film must then be mechanically removed and re-applied. Crews must therefore treat the maximum overlay time as a hard scheduling constraint, not a guideline, and plan the concrete pour around it.
Where it is used
- Bonding new concrete or screed toppings to existing hardened concrete slabs and pavements
- Structural concrete repairs where a fresh repair mortar or micro-concrete must bond to a cut-out, prepared substrate
- Bonded and granolithic floor toppings in factories, warehouses and loading bays
- Old-to-new junctions on roads, bridges, flyovers and pavement reconstruction
- Forming a substrate/repair barrier where the parent concrete is permanently damp or wet
- Industrial and infrastructure works requiring a structural bond at both horizontal and (formwork-supported) vertical surfaces
Key advantages
- Positive adhesion that exceeds the tensile strength of the host concrete, giving a genuinely structural bond
- Solvent-free and 100% solids — safe to use in enclosed, poorly ventilated spaces and non-flammable
- Can be applied to dry OR damp substrates, a major advantage on Indian sites and in water-contact structures
- Long open / overlay time and slow cure allow time to fit reinforcement and erect formwork before placing concrete
- High mechanical strength (compressive ~70 N/mm2, tensile ~30 N/mm2)
- Differentially pigmented base (white) and hardener (green) give clear visual confirmation of correct mixing
- Suitable for both internal and external use and for high-temperature working
- Complies with ASTM C881 for epoxy bonding systems
Limitations & considerations
- Must not be applied when substrate/ambient temperature is below 5C or is 5C and falling
- Maximum overlay time is a hard limit — if the new concrete is not placed while the film is tacky, the cured film acts as a slip plane and must be mechanically removed and re-applied
- Overlay/working times shorten significantly as temperature rises (e.g. working life drops from ~160 min at 25C to ~80 min at 35C), demanding tight pour scheduling in Indian summers
- As a two-component pre-weighed system, full units should be mixed; part-mixing risks incorrect ratio and incomplete cure
- Substrate must be properly prepared — clean, sound, roughened and free of laitance, oil, dust and curing compound — or the bond will fail in the weak surface layer, not the product
- Tools must be cleaned with Fosroc Solvent 102 immediately; hardened epoxy can only be removed mechanically
- It is a bonding agent, not a repair mortar or waterproofing membrane — it works as part of a system, not on its own
Selection & best practice
Always treat substrate preparation and pour timing as the two make-or-break steps. Mechanically roughen the old concrete (light scabbling or grit-blasting), remove all laitance to expose aggregate, and clean off oil, grease, dust and any curing compound — then verify soundness with a pull-off test before priming. Stir the base and hardener separately to redisperse settlement, combine the full pre-weighed pack, and mix with a slow-speed drill and paddle for about 2 minutes, scrape the sides, and mix a further 2 minutes until a uniform single colour confirms blending. Apply an unbroken brush- or roller-coat across the entire substrate, then place the fresh concrete, screed or mortar while the film is still tacky and strictly within the maximum overlay time for the prevailing temperature. In ambient conditions above 35C, store unmixed material in the shade, keep tools cool, avoid midday application, and keep Fosroc Solvent 102 ready for immediate tool cleaning. For confirmed batch-specific values for the EP03-IM grade, always work to the current Fosroc TDS for the pack you receive.
Specifications
| Product type | Two-component, solvent-free epoxy-resin concrete bonding agent (base + hardener) |
| Appearance | Base white, hardener green — mix to uniform colour |
| Compressive strength | 70 N/mm2 (ASTM D695) |
| Tensile strength | 30 N/mm2 (ASTM D638) |
| Slant shear strength | 36 N/mm2 (BS 6319, Part 4) |
| Water absorption | 0.05% (ASTM D570) |
| Standards compliance | ASTM C881: Type II, Grade 2, Class E & F |
| Working life (4 ltr pack) | ~160 min @ 25C; ~90 min @ 30C; ~80 min @ 35C |
| Maximum overlay time | 16 hours @ 25C; 12 hours @ 35C; 5 hours @ 45C |
| Minimum overlay time | Overlay when tacky but not wet |
| Full cure | 5 days @ 35C; 4 days @ 45C |
| Minimum application temperature | 5C |
| Coverage (theoretical) | 3.5 – 4.0 m2/litre |
| Pack sizes | 1 litre and 4 litre packs |
| Shelf life | 12 months in original unopened packs, dry storage |
| Fire | Non-flammable |
Industry use cases
Highways & Bridges
Bonding new wearing-course concrete, repair patches and overlays to existing pavement and bridge-deck concrete on road and flyover rehabilitation projects across Delhi NCR and pan-India.
Industrial Flooring
Welding bonded and granolithic floor toppings to existing slabs in factories, warehouses and loading bays so the topping resists forklift and wheel-load shear without delamination.
Structural Concrete Repair
Acting as the bond coat between a prepared, cut-out substrate and Fosroc Renderoc repair mortars or Conbextra micro-concrete, ensuring the repair behaves monolithically with the parent member.
Water-Retaining & Below-Grade Structures
Used on permanently damp or wet substrates such as tanks, basements and tunnels where its damp-tolerance and solvent-free, non-flammable formulation suit enclosed, ventilation-limited spaces.
Precast & Construction Joints
Creating a structural bond at construction joints and old-to-new interfaces where reinforcement and formwork must be fitted within the product’s long open time before concreting.
Frequently asked questions
What exactly is Fosroc Nitobond EP03-IM used for?
Can Nitobond EP03-IM be applied to a damp surface?
How long do I have to place the new concrete after applying it?
What is the coverage and what pack sizes are available?
Is it strong enough for structural repairs?
How is it different from a standard Nitobond EP or an acrylic bonding agent?
How we position Fosroc Nitobond EP03-IM
Within the Fosroc range, Nitobond EP03-IM sits at the structural, epoxy end of the Nitobond bonding-agent family. Where a lighter-duty, water-based bond will do — plaster repairs, non-structural screeds or where re-wettable application is acceptable — Fosroc Nitobond SBR (styrene butadiene latex) or Nitobond AR are the lower-cost choices. EP03-IM is specified when the interface must transmit structural load and tolerate damp or hot conditions. It is most often used as the bond coat in a complete Fosroc repair system alongside Renderoc hand-placed and spray repair mortars, Conbextra free-flow micro-concretes and grouts, and Nitoprime primers, with Fosroc Solvent 102 for tool cleaning. Against the wider Indian market, credible alternatives a specifier may evaluate include Sika’s epoxy bonding agents (e.g. Sikadur-32 / Sikadur range) and SikaTop Armatec for bonding and reinforcement protection, MBS (MYK/MBS) epoxy bonding agents, Dr. Fixit’s Pidiproof/Pidicrete epoxy and latex bond coats, and STP (Sun Tech Polymers) concrete bonding agents. The decision usually turns on the required overlay time, the substrate condition (damp vs dry), the structural demand of the bond, and the rest of the repair system already specified. As an authorised Fosroc distributor and applicator serving Delhi NCR and pan-India, Space Arc Engineering can supply Nitobond EP03-IM with the matching Fosroc repair-system products, current batch TDS/MSDS, and on-site application guidance.
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