Fosroc Nitoseal 280
Two-part, self-levelling epoxy-urethane pouring sealant engineered for heavy-traffic internal floor and saw-cut joints in factories, warehouses and food-processing facilities.
What is it?
A two-part, pouring-grade joint sealant formulated from a blend of epoxy and urethane polymers. It is self-levelling, cures to a tough yet semi-flexible seal, and is designed specifically for horizontal floor joints rather than vertical or facade movement joints.
Where is it used?
Internal floor joints subjected to heavy industrial traffic, hard-wheeled forklifts and point loads, factory and warehouse floors, food-processing and beverage plants, cold-store and pharmaceutical floors, and sawn (saw-cut) contraction joints in long-strip and large-area concrete slabs.
Why use it?
It carries wheel loads and supports the joint arrises, resists common chemicals and hydrocarbon fuels, and bonds to clean dry concrete without a primer. The pouring grade self-levels into wide and irregular joints, giving a fast, neat, low-labour seal where gun-grade products struggle.
How is it applied?
Saw or clean the joint, remove all dust by power brushing or dry blasting, blow clean with oil-free air, insert closed-cell backer rod or debonding tape, mix the colour pack and hardener into the base, then pour directly from the container or via a barrel gun into the joint and top up as it flows out.
About Fosroc Nitoseal 280
Fosroc Nitoseal 280 is a heavy-duty, pouring-grade floor joint sealant built around a hybrid blend of epoxy and urethane polymers. Unlike conventional gun-applied polyurethane or polysulphide sealants that stay soft and elastic to absorb large building movement, Nitoseal 280 deliberately cures harder and tougher (Shore A 60 to 80) so that it shares load with the surrounding concrete and protects the joint edges, or arrises, from spalling under steel-wheeled and hard-tyred traffic. It is supplied as a two-component system in which the entire colour pack and hardener are added to the base resin; the integral colour change confirms thorough mixing on site. Once blended, the material is self-levelling and is poured directly into horizontal joints, where it flows into irregularities and sets to a uniform, neat finish. The product traces back to Fosroc’s Middle East and international range and is widely marketed in India today under the updated identity Nitoseal PU 280, which contractors and procurement teams should be aware of when cross-referencing data sheets, packs and pricing. For Indian projects, Space Arc Engineering supplies Nitoseal 280 / PU 280 as an authorised Fosroc distributor and applicator across Delhi NCR and Pan-India, with the associated Nitoprime 25 primer, debonding tape, backer rod and Fosroc Solvent 102 available as a complete jointing system.
The technical insight
The defining technical trade-off in Nitoseal 280 is hardness versus movement. By design it is a low-movement sealant with a 10% movement accommodation factor (MAF), meaning the total joint movement from concrete shrinkage and thermal change must stay within 10% of the designed joint width. This is the opposite philosophy to high-movement elastomeric sealants such as Fosroc’s own Thioflex 600 polysulphide or a Sikaflex polyurethane, which accept 25% or more but cannot carry load. The epoxy-urethane chemistry gives Nitoseal 280 its characteristic dual behaviour: the epoxy fraction delivers rigidity, adhesion and chemical resistance, while the urethane fraction restores a limited degree of resilience so the seal is not brittle. A practical consequence is the 28-day rule. Because the bulk of drying shrinkage in a fresh concrete slab occurs within the first 28 days, sealing too early loads the cured sealant beyond its modest movement band and causes adhesive or cohesive failure. The data sheet therefore directs that sealing be delayed to the final stages of construction, after internal temperatures stabilise and early shrinkage is largely complete. Adhesion to dry, sound concrete is achieved without a primer, but where joints may be permanently immersed in water or where optimum bond is specified, Nitoprime 25 is required first.
Where it is used
- Heavy-duty saw-cut (sawn) contraction joints in industrial concrete floor slabs
- Construction and movement joints in factory, plant and workshop floors carrying forklift and pallet-truck traffic
- Floor joints in warehouses, distribution centres and logistics hubs with hard-wheeled MHE
- Hygienic floor joints in food-processing, dairy, beverage and pharmaceutical facilities
- Long-strip flooring joints and large internal slab-on-grade areas
- Vehicle workshop, maintenance bay and service-yard floor joints exposed to fuels and oils
- Joints over Fosroc resin-mortar-reformed or repaired arrises requiring a load-bearing seal
Key advantages
- Load-bearing seal that supports joint arrises under heavy wheel and point loads, reducing edge spalling
- Self-levelling pouring grade flows into wide and irregular horizontal joints for a fast, neat, uniform finish
- Bonds to clean, dry concrete without a primer in most floor situations, saving a process step
- Good chemical resistance to common mineral acids, alkalis, petroleum-based fuels and steam
- Integral colour pack gives visual confirmation of correct mixing and a range of finished colours
- Tough yet semi-flexible cured seal suits hard-trafficked industrial environments
- Workable on site by pouring direct from the container or via a Nitoseal barrel gun for narrower joints
- Backed in India by Space Arc Engineering as an authorised Fosroc distributor with the full jointing system
Limitations & considerations
- Low movement capacity, only a 10% movement accommodation factor, so it is unsuitable for high-movement or large thermal-cycling joints
- Strictly for horizontal floor joints, it is not intended for vertical, facade or overhead joints
- Cannot be used as a water-retaining or hydrostatic waterstop, it is a floor joint sealant, not a waterbar
- Requires a minimum 28-day delay after concreting before sealing, which must be programmed into the project
- Two-part, batch-mixed material with a limited working time once the components are combined
- Surfaces must be genuinely dry and dust-free, damp or contaminated joints compromise adhesion
- Immersed or optimum-adhesion situations need a separate Nitoprime 25 primer coat
- Cured hardness, not a soft elastomer, so movement is accommodated by the joint geometry, not by sealant elongation
Selection & best practice
Design the joint before specifying the sealant. Keep total expected movement within the 10% MAF: confirm joint width against anticipated shrinkage and thermal range, and delay sealing at least 28 days after pouring so that early concrete shrinkage is complete. Follow the data-sheet sealant-depth rule by joint width: for 6 to 12 mm joints set depth equal to width; for 12 to 25 mm joints use 12 to 20 mm depth; over 25 mm use a depth of one-half to three-quarters of the width. Control the depth and prevent three-sided adhesion with a firm closed-cell foam backer rod, or use Nitoseal debonding tape in the joint base where no backer rod is fitted. Prepare meticulously: cut or clean the joint, remove all laitance and saw-cut dust by rotary power brush or dry abrasive blasting, then blow out with oil-free compressed air so the joint is clean and bone-dry. Prime with Nitoprime 25 only where optimum adhesion is required or where the joint may be immersed. Add the full colour pack and hardener to the base and mix thoroughly until the colour is uniform, scrape the sides, and complete mixing before pouring. Pour to the required level, top up after a few minutes once it has flowed into all irregularities, and strip any masking tape immediately. Clean tools with Fosroc Solvent 102. Estimate quantity as width (mm) x depth (mm) x length (m) divided by 1000 to give litres.
Specifications
| Product type | Two-part, pouring-grade floor joint sealant |
| Chemistry | Blend of epoxy and urethane polymers |
| Grade / consistency | Self-levelling pouring grade (horizontal joints) |
| Movement accommodation factor (MAF) | 10% |
| Shore A hardness | 60 to 80 |
| Specific gravity | 1.31 |
| Cure @ 20°C | Initial 24 hours; full cure 3 days |
| Cure @ 35°C | Initial 12 hours; full cure 2 days |
| Application temperature | +5°C to 45°C |
| Service temperature | -10°C to 70°C |
| Chemical resistance | Good vs common mineral acids, alkalis, petroleum-based fuels and steam |
| Primer | Not normally required on dry sound concrete; Nitoprime 25 for immersion / optimum adhesion |
| Joint depth (6 to 12 mm width) | Equal to width |
| Joint depth (12 to 25 mm width) | 12 to 20 mm |
| Joint depth (over 25 mm width) | 1/2 to 3/4 of width |
| Colours | Range of colours via separate colour pack (visual mix control) |
| Pack size | 4.0 litre pack (Nitoprime 25 in 1.0 litre pack) |
| Mixing | Slow-speed drill 300 to 500 rpm with MR2 paddle, approx 5 minutes total |
| Shelf life | 12 months in original sealed containers, stored below 25°C, out of direct sunlight |
| Orientation | Horizontal floor joints only (not for vertical joints) |
Industry use cases
Warehousing & Logistics
Sealing saw-cut and construction joints across large slab-on-grade warehouse floors where forklifts and reach trucks run on hard polyurethane wheels; the load-bearing seal protects arrises and prevents joint-edge breakdown that damages MHE and racking.
Food & Beverage Processing
Hygienic, chemical-resistant floor joints in dairies, breweries and food plants subject to washdown, mild acids and alkalis; the self-levelling finish leaves no recesses that trap product or harbour contamination.
Manufacturing & Heavy Industry
Movement and contraction joints in factory and machine-shop floors exposed to point loads, dropped tools and occasional fuel or oil spillage, where a soft elastomeric sealant would be torn or extruded under traffic.
Automotive & Maintenance Facilities
Service-bay, workshop and depot floor joints exposed to petroleum-based fuels and lubricants, where the hydrocarbon resistance of the epoxy-urethane blend outperforms standard floor sealants.
Cold Storage & Pharma
Joints in temperature-controlled and clean-room slabs operating within the -10°C to 70°C service band, sealed during the final fit-out stage after the slab has stabilised and shrinkage has occurred.
Frequently asked questions
What type of sealant is Fosroc Nitoseal 280?
What is the movement accommodation factor of Nitoseal 280?
Does Nitoseal 280 need a primer?
How long should I wait after concreting before sealing?
Is Nitoseal 280 the same as Nitoseal PU 280?
How much Nitoseal 280 do I need and what pack size does it come in?
How we position Fosroc Nitoseal 280
Within Fosroc’s jointing range, Nitoseal 280 (now Nitoseal PU 280) occupies the heavy-duty, load-bearing floor-joint niche, and it should not be confused with the wider Nitoseal gun-grade polyurethane sealants or with high-movement products. Where a joint must flex significantly, such as facade, expansion and water-retaining structures, Fosroc Thioflex 600 (polysulphide) or a polyurethane gun-grade is the correct choice, while Fosroc Colpor 200PF is the comparable pouring-grade option engineered specifically for trafficked road and pavement expansion joints. Choose Nitoseal 280 when the priority is arris support and chemical resistance under hard wheeled traffic on internal floors, and choose an elastomeric sealant when the priority is accommodating movement. Credible alternatives from other manufacturers include Sika’s Sikaflux and Sikaflex floor-joint systems, BASF/MBS MasterSeal floor-joint sealants, and STP (Choksey/Pidilite group) industrial floor-joint products; each offers broadly similar epoxy or polyurethane chemistries, and final selection should be driven by the joint’s movement, load and chemical-exposure requirements rather than brand alone. Space Arc Engineering, as an authorised Fosroc distributor and applicator in Delhi NCR and Pan-India, supplies Nitoseal 280 / PU 280 with the matching Nitoprime 25, backer rod, debonding tape and Solvent 102, and provides specification and site-application support to ensure the correct product is matched to each joint.
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