About Fosroc Nitoseal PU280

Fosroc Nitoseal PU280 (formerly marketed as Nitoseal 280) is a two-component, pouring-grade joint sealant built specifically for the punishing conditions of industrial floors. Unlike the soft, gun-grade elastomeric sealants used on facades and movement joints, PU280 is formulated from a blend of epoxy and urethane polymers a combination chosen to deliver a hard-wearing, load-bearing edge while retaining a limited but useful degree of flexibility. The result is a seal that supports the concrete arris (the cut edge of the joint) under heavy wheel loads instead of being squeezed out or chipped away by forklift and pallet-truck traffic. Once the colour pack, hardener and base are combined, the mixed material self-levels, so it can simply be poured into a horizontal joint to produce a clean, uniform finish with minimal tooling. Nitoseal PU280 is supplied with a separate colour pack that doubles as a visual mixing indicator, so the operative can see when the two components are fully blended. In India it is distributed in 4.0 litre packs and is widely specified for sawn contraction joints in long-strip warehouse and factory slabs. Space Arc Engineering supplies and applies Nitoseal PU280 as an authorised Fosroc distributor and applicator across Delhi NCR and Pan-India, alongside the matching Nitoprime 25 primer and Nitoflor Sol cleaner from the same system.

The technical insight

The defining characteristic of Nitoseal PU280 is that it is a hard, semi-rigid floor-joint sealant, not a high-movement elastomer. Its movement accommodation factor (MAF) is 10% of the joint width modest by sealant standards but deliberate, because floor joints in a stabilised internal slab move very little once concrete shrinkage is complete. That low MAF is the trade-off that buys load-bearing performance: a Shore A hardness of roughly 60-80 lets the cured sealant transfer wheel loads across the joint and protect the arris, where a low-modulus polyurethane (Shore A in the low 30s) would deflect and let the edges spall. This is why Fosroc restricts PU280 to horizontal joints only it relies on self-levelling and is not intended to be tooled vertically. Cure is governed by ambient temperature: initial cure is around 24 hours at 20C, accelerating to about 12 hours at 35C, with full cure in 3 days (20C) or 2 days (35C). The specific gravity of 1.31 and good resistance to mineral acids, alkalis, petroleum-based fuels and steam make it well matched to process floors. Crucially, joint timing is as important as the product: because the bulk of drying shrinkage occurs in the first 28 days, sealing should be delayed until after that period so the joint width has stabilised before the relatively stiff sealant is placed.

Where it is used

• Sawn contraction (induced) joints in long-strip industrial floor slabs
• Internal floor and construction joints in factories and manufacturing plants
• Warehouse and distribution-centre floors under forklift and pallet-truck traffic
• Food-processing and beverage-plant floors requiring chemical and steam resistance
• Cold-store and refrigerated-warehouse floor joints
• Maintenance bays, workshops and vehicle-service facilities exposed to fuels and oils
• Large internal areas where a self-levelling, neat joint finish is required
• Re-sealing of degraded floor joints over Fosroc resin-based repair mortar reinstatement

Key advantages

• Load-bearing across the joint supports the concrete arris under heavy wheel loads
• Self-levelling pouring grade gives fast placing and a uniform, neat finish on long floor runs
• Bonds to dry, clean, sound concrete without a primer in most internal applications
• Good resistance to common mineral acids, alkalis, petroleum-based fuels and steam
• Tough, resilient seal with limited flexibility suited to low-movement floor joints
• Separate colour pack provides visual confirmation of thorough mixing
• Available in a range of colours to match or contrast with the floor finish
• Backed by the wider Fosroc system Nitoprime 25 primer and Nitoflor Sol cleaner

Limitations & considerations

• Not suitable for vertical joints designed for horizontal, self-levelling use only
• Low 10% movement accommodation factor unsuitable for genuine expansion or high-movement joints
• Two-part product with a limited working time once mixed; full batch must be placed promptly
• Requires joints to be left until the final stages of construction (typically after 28 days) so concrete shrinkage is largely complete
• Joint surfaces must be clean, dry and dust-free contamination, damp or laitance will compromise adhesion
• Total immersion or optimum-adhesion situations require priming with Nitoprime 25
• Contains epoxy resins skin sensitisation risk, so gloves and barrier cream are needed
• Storage life and properties degrade if stored above 25C; shelf life is 12 months unopened

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Nitoseal PU280

Within the Fosroc Nitoseal range, PU280 occupies the heavy-duty floor-joint niche it is the stiff, load-bearing, pouring-grade member of the family, distinct from gun-grade elastomeric sealants like Nitoseal PU40 (low-modulus polyurethane, 25% MAF) and Nitoseal 220/250 used for movement and building joints. Where a project needs a polysulphide for chemical-resistant movement joints, Fosroc’s Thioflex 600 is the natural counterpart, while Colpor 200PF is Fosroc’s pourable cold-applied sealant for trafficked external pavement and bridge-deck joints, accommodating far higher movement than PU280’s 10% MAF. Choosing between them is governed by movement, traffic and orientation: PU280 for low-movement internal floor joints under wheel loads; PU40/Thioflex for higher-movement and vertical joints; Colpor for high-movement external carriageway joints. Credible equivalents in the Indian market include Sika’s Sikaflex epoxy-polyurethane floor-joint sealants (such as the Sikaflex PRO/floor-joint grades), MBCC/Master Builders Solutions MasterSeal joint sealants, and Pidilite STP (Dr. Fixit) joint-sealant systems specifiers often cross-reference these on hardness, MAF, chemical resistance and load-bearing rating. Space Arc Engineering’s role is to match the right sealant to the joint’s actual service conditions rather than default to a single product, and to back the supply with correct primer selection, joint design and on-site application.

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