Fosroc Nitoseal MB82
A hot-poured rubber/bitumen joint sealant from Fosroc’s Nitoseal MB family, formulated for movement and construction joints in horizontal concrete and asphalt pavements.
What is it?
Nitoseal MB82 is a hot-applied (hot-poured) rubber/bitumen joint sealant in Fosroc’s Nitoseal MB series. Supplied as a black plastic solid that is melted on site and poured into horizontal joints, where it cools to form a flexible, weather- and water-resistant seal.
Where is it used?
Horizontal movement, construction and contraction joints in concrete roads, hardstandings, industrial floor slabs, podium and deck areas, and water-excluding structures, plus crack and joint maintenance in asphalt and concrete pavements.
Why use it?
It gives a tough yet flexible seal that bonds to concrete and asphalt, resists dirt and grit pick-up under traffic, returns to service quickly after cooling, and is an economical choice for long runs of horizontal pavement joints.
How is it applied?
Cut into pieces and melted in a thermostatically controlled, oil-jacketed, stirred melter to the recommended pouring temperature, then poured into a clean, dry, primed sealing slot fitted with a bond breaker / backer rod, finishing a few mm below the trafficked surface.
About Fosroc Nitoseal MB82
Fosroc Nitoseal MB82 is part of the Nitoseal MB range — Fosroc’s family of rubber/bitumen (modified-bitumen) joint sealants that also includes the gun-grade MB175 and the hot-poured pavement grades MB77 and MB333. On Fosroc’s own product listing, MB82 is described simply as a “bitumen based sealant for hot performance,” which places it squarely in the hot-applied, pour-grade group rather than the cartridge/gun-grade elastomerics such as the polyurethane Nitoseal PU or the silyl-modified Nitoseal MS sealants. In practice this means MB82 arrives as a solid block or slab, is heated in a proper melting kettle on site, and is poured molten into horizontal joints where it sets on cooling into a firm but flexible compound. Because it is bitumen-based, MB82 is naturally compatible with asphalt and concrete substrates, is unaffected by the alkalis and sulphates present in cementitious surfaces, and forms a seal that copes well with the dirt, grit and trafficking typical of roads, yards and industrial floors. It is a horizontal-joint product: like all hot-poured bitumen sealants it relies on gravity and a flat pour, so it is not intended for vertical or overhead joints, façade movement joints, or visible architectural sealing where a coloured low-modulus elastomeric (Nitoseal MS or PU) or a polysulphide (Thioflex) would be specified instead. For Indian projects, Nitoseal MB82 is manufactured and supplied through Fosroc Chemicals (India) Pvt. Ltd., and Space Arc Engineering supplies it as an authorised Fosroc distributor and applicator across Delhi NCR and pan-India, together with the matching Fosroc primer, backer rod and hot-melt application support.
The technical insight
Hot-poured rubber/bitumen sealants like the Nitoseal MB family achieve their movement capacity through the thermoplastic, rubber-toughened bitumen matrix rather than through a chemical cure. The block is melted, poured and simply cools — there is no skinning time, pot life or multi-day cure to manage, which is why these products allow a rapid return to traffic. The trade-off is that performance is extremely sensitive to heating discipline: the compound must reach but not exceed its pouring window, because over-heating degrades the polymer modifier and permanently impairs adhesion and elasticity. Across this Fosroc range the published anchors are a movement accommodation factor of about 25% in butt joints (assessed to BS 6093), a pouring temperature in the order of 165–175°C with a safe heating ceiling around 185°C, and concrete substrates primed with Fosroc Primer B2 while warmed metal needs no primer. The sealant is a 100%-solids plastic solid with a density near 1.15 and is not resistant to petrol, diesel, lubricating oils or greases — a deliberate distinction from fuel-resistant pavement sealants such as the cold-applied Colpor 200PF. Joint geometry follows the same logic as the rest of the family: a controlled width-to-depth ratio with a bond breaker at the base so the sealant strains across the gap rather than being three-side bonded. Note that the exact numeric pouring temperature, BS 2499 classification and pack size printed on the current Nitoseal MB82 datasheet should always be confirmed against Fosroc’s latest country-specific TDS before specification, as Fosroc periodically revises and renames products in this series.
Where it is used
- Sealing transverse and longitudinal movement, expansion and contraction joints in concrete roads, runways, aprons and hardstandings
- Construction and contraction joints in horizontal industrial floor slabs, warehouses, loading bays and external paved yards
- Joint sealing in podiums, decks and water-excluding / water-retaining horizontal structures where a flexible hot-melt seal is acceptable
- Routine maintenance and resealing of joints and routed cracks in existing concrete and asphalt pavements
- Sealing joints in precast concrete paving and block-paved areas subject to vehicle trafficking
- Horizontal joints in bituminous and asphalt surfacings where a compatible bitumen-based sealant is required
Key advantages
- Hot-poured application gives fast cooling and rapid return to traffic, minimising lane / floor closure time
- Rubber-toughened bitumen forms a firm yet flexible seal that accommodates joint movement (around 25% MAF in butt joints for this family)
- Naturally compatible with both concrete and asphalt / bituminous surfaces
- Unaffected by the alkalis and sulphates present in cementitious substrates
- Resists dirt and grit ingress associated with trafficked pavements, helping the seal stay intact
- Economical for long runs of horizontal pavement and floor joints compared with cartridge elastomerics
- 100% solids with no solvent loss or cure shrinkage once poured
- Backed by Fosroc India manufacture and local technical support through authorised distributors
Limitations & considerations
- Horizontal joints only — being a pour-grade hot melt it cannot be used in vertical, inclined or overhead joints
- Requires specialised, thermostatically controlled, oil-jacketed melting and pouring equipment with a stirrer; not a cartridge-gun product
- Performance is sensitive to over-heating — exceeding the safe heating temperature permanently damages adhesion and elasticity
- Bitumen-based and black only, so unsuitable for visible architectural, façade or coloured joint sealing
- Not resistant to petrol, diesel, lubricating oils or greases — fuel-resistant grades (e.g. Colpor 200PF) are needed in fuelling areas
- Lower movement capacity than low-modulus PU / MS / polysulphide elastomerics, so unsuitable for high-movement structural expansion joints
- Hot-work safety controls are mandatory (hot bitumen burn and fume risk)
- Exact MB82-specific pouring temperature, BS classification and pack size must be confirmed against the current Fosroc local datasheet before specification
Selection & best practice
Design the sealing slot to a controlled width-to-depth ratio (typically around 2:1 for this family) with sensible minimum dimensions — for hot-poured pavement sealants in this range, slots are commonly not less than about 13 mm wide x 15 mm deep and up to roughly 30 mm wide x 25 mm deep, but always size to the verified MB82 datasheet and to BS 6093 for the movement expected. Saw-cut or form the slot, then grit-blast or grind the joint faces (avoid polishing the arrises), blow out with dry, oil-free compressed air, and ensure the joint is sound, dry and frost-free. Fit a closed-cell bond breaker / backer rod (such as Fosroc Hydrocell or a backing rod) at the base so the sealant bonds only to the two faces and can strain across the gap; never let it bond on three sides. Prime concrete faces with Fosroc Primer B2 and let the solvent flash off before pouring; warm metal faces with a torch immediately before sealing rather than priming. Melt the compound in a proper oil-jacketed, stirred, thermometer-fitted kettle, bring it to the recommended pouring temperature without exceeding the safe heating ceiling, and pour to finish a few millimetres below the trafficked surface. Pour at the upper end of the temperature window in cold weather to offset chilling by cold concrete, and confirm full cooling before reopening to traffic.
Specifications
| Product family | Fosroc Nitoseal MB (rubber / bitumen joint sealants) |
| Sealant chemistry | Rubber-toughened / modified bitumen |
| Grade | Hot-applied (hot-poured) pour grade — horizontal joints |
| Form | Plastic solid (block / slab), melted on site |
| Colour | Black |
| Solids content | 100% (no solvent loss on pouring) |
| Movement accommodation factor (typical for family, BS 6093) | ~25% in butt joints |
| Pouring temperature (typical for family) | ~165–175°C |
| Safe heating temperature (typical for family) | ~185°C |
| Cure type | Thermoplastic — sets on cooling, no chemical cure |
| Primer | Fosroc Primer B2 on concrete; warmed metal needs no primer |
| Suitable substrates | Concrete, asphalt / bituminous surfacing, metal |
| Chemical resistance | Not resistant to petrol, diesel, lubricating oils or greases |
| Related standard (family) | BS 2499 Type N1 / BS 6093 joint design (confirm MB82 classification on current TDS) |
| Manufacturer (India) | Fosroc Chemicals (India) Pvt. Ltd. |
| Indian supply | Space Arc Engineering — authorised Fosroc distributor & applicator, Delhi NCR + Pan-India |
Industry use cases
Highways & pavements
Sealing transverse and longitudinal movement and contraction joints in concrete carriageways, service roads and hardstandings, with rapid reopening to traffic after the poured sealant cools.
Industrial & warehousing floors
Construction and contraction joints in heavy-duty ground-bearing floor slabs, loading bays and external paved yards where forklift and truck trafficking demands a tough, grit-resistant seal.
Water-excluding & infrastructure structures
Horizontal joints in podiums, decks, channels and water-excluding concrete structures where a flexible bitumen-based hot-melt seal is acceptable.
Repair & maintenance
Resealing aged or failed joints and routed cracks in existing concrete and asphalt pavements as part of periodic road and floor maintenance programmes.
Logistics & ports
Sealing trafficked joints in container yards, aprons and precast/block-paved areas exposed to weather and constant vehicle movement.
Frequently asked questions
Is Fosroc Nitoseal MB82 a real product?
What type of sealant is Nitoseal MB82 — and is it gun or pour grade?
Which joints and substrates is it suitable for?
What movement can it accommodate and how should the joint be designed?
Does it resist fuels and oils?
Can Space Arc Engineering supply MB82 and support the application?
How we position Fosroc Nitoseal MB82
Within Fosroc’s joint-sealant portfolio, Nitoseal MB82 is a value-engineered, hot-poured rubber/bitumen sealant for horizontal pavement and floor joints — the same broad class as Nitoseal MB77 and the BS 2499 Type N1 polymer-modified MB333, and a close relation of the gun-grade rubber/bitumen MB175. It is not an architectural or high-movement product: where you need coloured, vertical, façade or high-strain structural movement joints, the right Fosroc choices are the low-modulus silyl-modified Nitoseal MS range, the polyurethane Nitoseal PU range, or the multi-component polysulphide Thioflex 600; for cold-applied, fuel-resistant pavement expansion joints Fosroc’s Colpor 200PF is the specification-grade answer. Among competitor systems, contractors will commonly weigh it against Sika’s Sikaflex elastomeric and hot-applied joint sealants, BASF/MBCC MasterSeal joint sealants, and STP (Shalimar Tar Products) bituminous and hot-poured sealants widely used on Indian roadworks. MB82’s pitch is straightforward: a proven, economical, traffic-ready bitumen seal for long horizontal joint runs, backed by Fosroc India manufacture and Space Arc Engineering’s local distribution and applicator support. Because Fosroc updates and renames products in this series, specifiers should always validate the current MB82 datasheet — pouring temperature, classification, pack size and any regional substitution — before issuing a specification.
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