Fosroc Nitobond EP
A solvent-free, two-part epoxy resin bonding agent that fuses fresh concrete and mortar to existing substrates with a bond stronger than the parent concrete itself.
What is it?
A two-component, solvent-free epoxy resin bonding agent (white base, green hardener) supplied in pre-weighed packs for onsite mixing.
Where is it used?
At the interface between new cementitious material and old concrete, on horizontal and formwork-supported vertical surfaces, in repairs, toppings and structural extensions.
Why use it?
It develops a bond that exceeds the tensile strength of good-quality concrete and doubles as a barrier coat against chloride-ion migration from the host concrete.
How is it applied?
Mix base and hardener to a uniform colour, brush onto a clean, prepared substrate, then place the new concrete or mortar while the film is still tacky.
About Fosroc Nitobond EP
Fosroc Nitobond EP is the go-to epoxy bonding agent when a specifier needs an old concrete surface and a fresh cementitious placement to behave as one monolithic element. It is built on solvent-free epoxy resins carrying pigments and fine fillers, and arrives as a two-part system in pre-weighed base and hardener tins. The deliberate colour coding, a white base and a green hardener, is not cosmetic; it gives the applicator on site clear visual proof that the two components have been fully blended before a brush ever touches the wall. That single detail removes one of the most common sources of bond failure on Indian sites, where mixing is often rushed.
Where Nitobond EP earns its keep is the interface. Poured concrete simply does not key reliably onto a smooth, cured, or contaminated surface, and the cold joint that results becomes the weak line a structure fails along. By coating the prepared substrate first, Nitobond EP creates a continuous, high-strength adhesive layer that the new placement grips into while the epoxy is still tacky. For engineers and contractors across Delhi NCR and the rest of India, it is a dependable choice for structural extensions, patch and overlay repairs, bonded floor toppings, and any situation where reinforcement or formwork has to be positioned before the new pour goes in.
The technical insight
The mechanism is straightforward but powerful. A hardened concrete surface has been laitance-covered, carbonated and smoothed by curing, so a fresh pour placed directly onto it forms only a mechanical, discontinuous contact that carries little tensile or shear load. Nitobond EP replaces that weak contact with a chemically cured epoxy film. The epoxy wets into the open pores and micro-texture of the prepared old concrete, and while it is still tacky the fresh cementitious material is placed against it, so the hydrating new concrete keys directly into the resin. The cured joint therefore transfers load as a continuum: independent testing to BS 6319 shows the interface bond exceeding the tensile strength of the host concrete, meaning failure, when forced, migrates into the parent concrete rather than along the joint. The long overlay window, up to 10 hours at 20°C, is the second half of the story: it holds the surface receptive long enough to fix steel and formwork and still place concrete without risking delamination, while the fully cured film also blocks the chloride-ion path from the host substrate into the repair.
Where it is used
- Bonding new concrete or mortar to existing hardened concrete at construction and cold joints
- Structural extensions and thickening of beams, columns, slabs and walls
- Patch repairs and reprofiling where a bonded repair mortar or micro-concrete is placed
- Bonded and granolithic floor toppings in factories, warehouses and loading bays
- Repairs to bridges, roads, pavements and industrial hardstanding
- As a barrier coat limiting chloride-ion migration from chloride-contaminated host concrete
- Substrates that will remain permanently damp or wet, where cement-based bond aids underperform
- Segmental and precast concrete construction where formwork and reinforcement precede the pour
Key advantages
- Cured bond strength exceeds the tensile strength of good-quality concrete, so joints fail in the parent concrete, not at the interface
- Long overlay time (up to 10 hours at 20°C, 6 hours at 30°C) lets crews fix steel and formwork before placing concrete
- Solvent-free formulation suitable for enclosed and internal work
- Colour-coded base and hardener give instant visual confirmation of thorough mixing
- Acts as a barrier coat against chloride-ion migration from the host concrete
- Tolerates dry or damp substrates, and performs where the substrate stays permanently wet
- Single-coat brush application keeps the process simple and fast on site
- GreenPro Ecolabel certified by CII, supporting green-building documentation
Limitations & considerations
- Must not be applied when substrate or ambient temperature is below 10°C; below that the components need warming to a maximum of 25°C in hot water before mixing
- Pot life is short in Indian summer conditions, falling to 2-3 hours at 30°C, so batches should be sized to what can be used quickly
- The fresh concrete or mortar must be placed while the film is still tacky; if the overlay window is missed the coat must be reapplied
- Substrate preparation is non-negotiable: laitance, dust, oil and grease must be fully removed or the bond will not develop
- The uncured product is inflammable, so no naked flame is permitted and it should not be used where hot works are ongoing
- Hardened epoxy can only be removed from tools mechanically; tools must be cleaned with Nitoflor Sol immediately after use
Selection & best practice
Get the substrate right first. All surfaces must be firm, clean and dust-free; remove laitance by etching with Reebaklens and wire-brushing, chip back to sound concrete where needed, and strip any oil or grease with a strong industrial detergent or degreaser before washing down with water and allowing to dry. Stir the base and hardener separately to disperse settlement, then pour the whole hardener tin into the base and mix with a slow-speed drill and paddle until the colour is completely uniform, scraping the sides. Brush on an unbroken coat; where it forms part of a repair barrier, apply a first coat, let it gel, then apply a second bonding coat. Place the new concrete or mortar while the film is still tacky, and always work within the overlay time for the site temperature. In hot weather size each batch to the pot life you actually have, and clean tools with Nitoflor Sol before the epoxy hardens.
Specifications
| Composition | Two-part, solvent-free epoxy resin (white base + green hardener) |
| Specific gravity | 1.15 to 1.2 g/cc |
| Pot life | 5-6 hrs at 20°C; 2-3 hrs at 30°C |
| Overlay time | 10 hrs at 20°C; 6 hrs at 30°C |
| Full cure | 7 days at 20°C; 5 days at 30°C |
| Compressive strength | 50 N/mm² at 7 days (BS 6319 Pt 2) |
| Tensile / flexural / shear strength | 20 / 35 / 10 N/mm² at 7 days (BS 6319) |
| Coverage | Approx. 2.6 m²/litre (substrate-dependent) |
| Pack sizes | 0.5, 1 and 4 litre packs; shelf life 12 months below 35°C |
Industry use cases
Bridges & Infrastructure
Bonds new concrete to old at deck extensions, pier repairs and pavement reinstatement, with a long overlay window that suits reinforcement and formwork fixing on large pours.
Industrial Flooring
Creates a durable, delamination-resistant bond for granolithic and bonded floor toppings in factories, warehouses and loading bays subject to heavy traffic.
Structural Repair & Rehabilitation
Ties bonded repair mortars and micro-concrete into the parent structure during beam, column and slab restoration, with a joint stronger than the host concrete.
Marine & Chloride-Exposed Structures
Doubles as a chloride-ion barrier coat on contaminated or permanently damp substrates, protecting new repairs in coastal and water-retaining structures.
Building Extensions
Joins new structural concrete to existing members in vertical and horizontal extensions where formwork supports the fresh placement.
Frequently asked questions
What exactly does Nitobond EP do?
How long after applying can I place the new concrete?
Can it be used on damp or wet surfaces?
What is the coverage and how is it packed?
How do I know it has been mixed correctly?
Is there a minimum application temperature?
How we position Fosroc Nitobond EP
Nitobond EP is the structural, epoxy-grade choice in Fosroc’s bonding range. Where the interface must remain permanently damp or must carry structural load, it is the right specification. For lighter-duty repairs, gauging of repair mortars, or where budget favours a polymer bond aid over an epoxy, Fosroc Nitobond SBR is the natural in-family alternative. In practice Nitobond EP is specified alongside the Fosroc repair system it bonds into, most often the Renderoc range of reinstatement mortars (such as Renderoc GP) or Fosroc micro-concretes, with Nitoflor Sol kept on hand for tool cleaning. Across our other brands, comparable epoxy or acrylic bonding agents are available from Sika (SikaTop Armatec / Sika Latex) and Dr. Fixit; our team can help match the bonding agent to the repair mortar and site conditions you are working with.
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