Fosroc Nitomortar HB
Solvent-free, lightweight high-build epoxy mortar for fast, chemical-resistant reinstatement of vertical and overhead concrete, formwork-free up to 30mm per layer.
What is it?
A three-component, solvent-free epoxy repair mortar with a lightweight filler that gives it strong ‘hanging’ or non-sag properties, letting it be built up thick on vertical and overhead concrete surfaces without formwork.
Where is it used?
Patch repairs and reinstatement of spalled or damaged concrete in soffits, beams, columns, walls, bridge undersides, jetties, water-retaining structures and chemical/marine environments where formwork is impractical.
Why use it?
It develops strength equal to high-quality concrete within about 3 days, resists a wide range of chemicals, has extremely low permeability and protects embedded reinforcement, all while being applied overhead in a single high-build pass.
How is it applied?
The substrate is prepared to a sound, roughened profile; exposed steel is primed with Nitoprime Zincrich Plus; the three components are site-mixed in full pre-weighed packs and trowel/float applied 10-30mm per layer, then finished and left to cure.
About Fosroc Nitomortar HB
Fosroc Nitomortar HB is a high-build epoxy repair mortar engineered for the fast, durable reinstatement of damaged concrete on vertical and overhead surfaces. It is built on a high-performance, solvent-free epoxy resin system and incorporates a special lightweight filler that gives the mixed mortar excellent non-sag or “hanging” characteristics. This is the defining feature of the product: it can be applied and built up to substantial thickness on soffits, beam undersides and walls without slumping and, critically, without the time and cost of erecting formwork. It is supplied as a three-component material in pre-weighed packs, so it is mixed on site in complete units and used straight away, removing the guesswork and quality risk of part-batching on a busy job. For contractors and consultants in India dealing with spalled cover concrete, corrosion-related repairs and aggressive exposure conditions, Nitomortar HB sits firmly in the premium, epoxy-based end of Fosroc’s repair range, distinct from the cementitious Renderoc family. It is intended for small-to-moderate localised patch repairs where speed of strength gain, chemical resistance and impermeability matter more than the lower unit cost of a polymer-modified cementitious mortar. Because it is an epoxy system, it also performs where conventional repair mortars struggle: chemical plants, effluent treatment works, marine and coastal structures, and industrial floors and bunds exposed to acids, alkalis and a range of industrial chemicals. As an authorised Fosroc distributor and applicator covering Delhi NCR and supplying Pan-India, Space Arc Engineering positions Nitomortar HB as the go-to solution when a repair must be completed overhead, gain strength quickly, and survive in a corrosive or chemically loaded environment.
The technical insight
The engineering logic of Nitomortar HB rests on two design choices. First, the solvent-free epoxy binder cures by chemical cross-linking rather than hydration, so the repair does not depend on ambient moisture or extended water curing to gain strength, and it reaches the strength of high-quality concrete within roughly three days. This is what makes it suitable for emergency and fast-turnaround repairs where conventional cementitious mortars would still be gaining strength. Second, the lightweight filler reduces the density of the wet mortar so that surface tension and the epoxy’s cohesion can hold the material in place overhead; this is why thicknesses up to 30mm per layer can be achieved on vertical and overhead surfaces in line with BS EN 1504 Part 3, the European standard for structural and non-structural concrete repair. The cured mortar has extremely low permeability, which is the property that actually protects embedded steel: by blocking the ingress of water, chlorides and sulphates, it slows the corrosion mechanisms that caused the spalling in the first place. For this reason the system is specified with Nitoprime Zincrich Plus on exposed reinforcement (an active zinc-rich primer) and, where a dry substrate needs priming, Nitoprime 28. The minimum recommended applied thickness is 10mm and the practical maximum is 30mm per layer; greater depths are built up in successive layers. As an epoxy, it is temperature- and pot-life sensitive, so mixing in complete pre-weighed packs and working within the pot life are non-negotiable for a sound repair.
Where it is used
- Reinstatement of spalled or delaminated cover concrete on beam soffits, slab undersides and column heads
- Overhead and vertical patch repairs where erecting formwork is impractical or uneconomic
- Emergency and fast-turnaround structural repairs requiring rapid strength gain
- Repairs in chemically aggressive environments such as effluent treatment plants, chemical process areas and industrial bunds
- Marine and coastal concrete repairs exposed to chloride and sulphate attack (jetties, sea walls, splash zones)
- Protection and reinstatement around corroded reinforcement steel as part of a corrosion-management repair system
- Localised repair of water-retaining and below-ground structures requiring low permeability
Key advantages
- Lightweight, non-sag formulation allows high-build application on vertical and overhead surfaces without formwork
- Develops strength equal to high-quality concrete within about 3 days for fast project turnaround
- Solvent-free epoxy system cures independent of ambient moisture and needs no water curing
- Extremely low permeability protects embedded reinforcement against further chloride and sulphate ingress
- Highly resistant to a wide range of acids, alkalis and industrial chemicals
- Conforms to BS EN 1504 Part 3 for concrete repair, supporting specification and compliance
- Supplied in pre-weighed three-component packs, eliminating site batching errors
- Can be applied in cool conditions down to 5°C
Limitations & considerations
- Epoxy system with a limited pot life once mixed; the full pack must be used promptly and partial mixing is discouraged
- Higher material cost than polymer-modified cementitious repair mortars such as the Renderoc range, so it is best reserved for repairs where chemical resistance, speed or overhead build are genuinely needed
- Intended for small-to-moderate localised patch repairs rather than large-volume or full-depth reconstruction
- Should not be applied when the substrate temperature is below 5°C and falling
- Coefficient of thermal expansion of an epoxy mortar differs from concrete, so very large or thin-feathered areas need detailing care
- Requires correct priming (Nitoprime Zincrich Plus on steel, Nitoprime 28 on dry substrates) and good surface preparation to perform as designed
Selection & best practice
Achieve a sound, clean, roughened substrate by mechanically breaking out all loose and contaminated concrete back to sound material and squaring the edges of the repair to avoid feather-edging. Expose and clean corroded reinforcement to a bright finish (abrasive blasting where possible) and apply two coats of Nitoprime Zincrich Plus, allowing each to dry. Prime dry substrates with Nitoprime 28 where required. Mix only complete pre-weighed packs by combining all three components and blending to a uniform colour and consistency, then apply by trowel or float within the pot life, building up in layers of 10 to 30mm and firmly compacting each layer against the substrate to eliminate voids. Do not part-mix packs, do not retemper with solvent, and do not apply when the substrate is below 5°C and falling. Reserve Nitomortar HB for repairs that truly need its epoxy performance; for routine large-area cementitious repairs, specify the appropriate Renderoc product instead. Always confirm the latest values and method against the current Fosroc Technical Data Sheet for the India market before specification.
Specifications
| Chemical type / system | Solvent-free epoxy resin system with lightweight filler |
| Components | Three-component, supplied in pre-weighed packs |
| Strength development | Equal to high-quality concrete within approx. 3 days |
| Minimum applied thickness | 10 mm |
| Maximum thickness per layer | 30 mm (vertical and overhead) |
| Standard | Conforms to BS EN 1504 Part 3 |
| Primer (reinforcement steel) | Nitoprime Zincrich Plus |
| Primer (dry substrate) | Nitoprime 28 |
| Permeability | Extremely low when properly compacted |
| Chemical resistance | Resistant to a wide range of acids, alkalis and industrial chemicals |
| Minimum application temperature | 5°C (not to be applied below 5°C and falling) |
| Initial hardness / full cure | Approx. 24 hours initial; approx. 7 days full cure at 20°C |
| Pack size (typical UK pack) | 9.3 kg pack yielding approx. 8.0 litres |
| Application method | Trowel / float |
Industry use cases
Bridges & Infrastructure
Reinstating spalled cover concrete on bridge beam soffits and pier caps where overhead access makes formwork impractical and traffic-management windows demand fast strength gain.
Water & Wastewater
Repairing concrete in effluent and sewage treatment structures where low permeability and resistance to sulphates and chemical attack protect both the concrete and embedded steel.
Marine & Coastal
Patch repairs to jetties, sea walls and splash-zone elements exposed to chloride-laden environments, using the mortar’s impermeability to slow further reinforcement corrosion.
Industrial & Chemical Plants
Localised reinstatement of acid- and alkali-attacked concrete in process areas, bunds and plinths where standard cementitious mortars would not survive the chemical exposure.
Commercial & High-Rise Buildings
Overhead and vertical repairs to slab soffits, beams and column heads in occupied or fast-track buildings where a quick, formwork-free, durable patch is needed.
Frequently asked questions
Is Fosroc Nitomortar HB a cementitious or epoxy repair mortar?
How thick can Nitomortar HB be applied in one layer?
How quickly does it gain strength?
What primers are used with Nitomortar HB?
Can it be used in chemical and marine environments?
Is Nitomortar HB available in India through Space Arc Engineering?
How we position Fosroc Nitomortar HB
Within Fosroc’s repair portfolio, Nitomortar HB occupies the premium epoxy-mortar niche for overhead and chemically aggressive work, complementing rather than replacing the cementitious Renderoc family (such as Renderoc HB and Renderoc S) used for routine, larger-area structural repairs. It is closely related to other Nitomortar epoxy mortars: Nitomortar S is a solvent-free epoxy reinstatement mortar for general patch repairs, while Nitomortar HB is specifically formulated lightweight for high-build vertical and overhead use. It is typically specified alongside Fosroc primers Nitoprime Zincrich Plus and Nitoprime 28, and the Nitobond epoxy bonding agents. Against the wider Indian market, credible alternatives in the epoxy and high-performance repair space include Sika (for example the Sikadur epoxy mortars and SikaTop/Sika MonoTop repair systems), MBS (MYK Arment) repair mortars, STP (Sika-acquired) protective and repair products, and Dr. Fixit (Pidilite) for cementitious repair and protection where an epoxy is not essential. For most overhead, fast-strength or chemically loaded repairs, Nitomortar HB and the Sikadur epoxy mortars are the closest like-for-like options; for cost-sensitive, large-area cementitious repairs, polymer-modified mortars from Fosroc Renderoc, Dr. Fixit or MBS are usually more economic. Space Arc Engineering can help specifiers and contractors select between these systems and confirm the right Fosroc product and ancillaries for the exposure, geometry and programme of each project.
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