About Fosroc Reebolith S

Fosroc Reebolith S is a chemical hardening and dustproofing treatment for in-situ and precast concrete floors. Supplied as a clear, ready-to-use liquid, it is not a coating that sits on top of the slab; instead it penetrates the surface and reacts with the free lime (calcium hydroxide) present in cured cement paste. The product is based on metallic fluorosilicates – principally magnesium fluorosilicate (MgSiF6) – and carries a wetting agent that lowers surface tension so the liquid is drawn deep into the capillary pore structure rather than simply forming a film. The reaction it drives is permanent: insoluble, very hard reaction products are formed within the top 2-4 mm of the surface, leaving behind a denser, harder, dust-free wearing layer with improved chemical resistance.\n\nFor an Indian industrial floor, this matters because most cast concrete – whether a new warehouse slab in an NCR logistics park or an ageing factory floor in Faridabad or Ludhiana – dusts under foot and forklift traffic, abrades quickly and is difficult to keep clean. Reebolith S addresses the root cause of dusting (weak, friable surface laitance and unbound lime) chemically, hardening the matrix from within. It is colourless once cured, leaves no slippery film, gives off no harmful fumes or odour, and needs no specialist equipment or skilled applicators – a soft broom and clean water are the main tools. Treated floors can later be over-painted, line-marked with thermoplastic, or simply left as a sealed, easy-clean wearing surface. Space Arc Engineering supplies Reebolith S across Delhi NCR and Pan-India and can advise on whether a fluorosilicate densifier or a heavier-duty topping is the right specification for a given floor.

The technical insight

The performance of Reebolith S is governed by a single acid-base reaction. Cured Portland cement always contains a reserve of free calcium hydroxide, Ca(OH)2, much of it concentrated in the weak surface laitance that causes dusting. When the fluorosilicate solution penetrates, it reacts according to: 2 Ca(OH)2 + MgSiF6 -> 2 CaF2 + MgF2 + SiO2 + 2 H2O. The products – calcium fluoride, magnesium fluoride and precipitated silica – are insoluble, hard crystalline solids that are physically larger than the lime they replace, so they block the capillary pores and bind the previously loose surface particles. The result is a densified, lower-porosity surface to a depth of roughly 2-4 mm. Two practical consequences follow. First, free lime must be present and accessible – the concrete must never be acid-etched before treatment, because that strips the very lime the reaction depends on; a simple field check is to drop dilute hydrochloric acid (5-10%) on the saturated floor, where continued fizzing means another coat is still needed and no reaction means saturation is complete. Second, the concrete must be mature: new grey concrete should be at least 14 maturity-days (14 days at +20C) and coloured concrete at least 28 maturity-days, so that the cement has hydrated and a stable lime reserve has formed. This is densification chemistry, distinct from sodium- or lithium-silicate densifiers, which instead react with lime to form calcium silicate hydrate.

Where it is used

• Hardening and dustproofing of concrete floors in factories, warehouses and storage godowns subject to foot and forklift traffic
• Dense, hygienic, washable floors in dairies, milking parlours, abattoirs, food-processing units and animal stalls
• Car parks and multi-storey parking decks where dusting and abrasion are problems
• Effluent and sewage treatment plants, and fodder and manure silos requiring chemically more resistant floors
• Workshops, garages and agricultural buildings needing a clean, oil- and fuel-tolerant surface
• Protection of external concrete – wall copings, bridges and steps – against weathering
• Hardening of precast concrete elements and paving flags before installation

Key advantages

• Supplied as a ready-to-use liquid – no mixing, dilution or batching required
• Penetrates and reacts within the concrete rather than forming a surface film, so it does not peel or flake
• Produces a permanently hard, abrasion-resistant and dust-free wearing surface
• Improves chemical resistance and tolerates petrol, oil and de-icing salt
• Yields a denser, smoother, easier-to-clean and more hygienic floor
• Colourless and emits no harmful vapours or odour, suitable for occupied and food-related areas
• Requires no specialist training or equipment – applied with a soft broom
• Can be over-coated later with pigmented paint or thermoplastic line-marking

Limitations & considerations

• Only works where free lime is present – cannot be applied to concrete that has been acid-etched, and is ineffective on non-cementitious substrates
• Requires mature concrete: at least 14 maturity-days for grey concrete and 28 for coloured concrete before treatment
• Densifies and dustproofs the existing surface but does not rebuild worn, spalled or structurally damaged concrete – repairs must be made first
• Not a decorative or high-build coating; it will not hide grinding marks or impart colour, and grinding scratches remain visible
• Metal, glass and painted surfaces must be masked, as splashes can etch or stain them
• Delicate or coloured concrete should be trial-treated first to check for blotching/discolouration
• Performance depends on substrate porosity and surface texture, so coverage and the number of coats vary from floor to floor
• Treated floors that need washing 1-2 hours after each coat require water access and adequate drainage on site

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Reebolith S

Reebolith S sits in Fosroc’s flooring and concrete-treatment range as an economical, chemical-reaction dustproofer and hardener for existing or new concrete slabs – the go-to where the brief is simply to stop a floor dusting and harden the wearing surface, rather than to apply a thick decorative or heavy-duty topping. Within the Fosroc portfolio it complements products such as Nitoflor Hardtop (dry-shake metallic/non-metallic floor hardeners) and the Nitoflor epoxy and PU floor coatings, which are specified when far higher abrasion, impact or chemical resistance or a coloured finish is required; Nitoprime 118 and Cleaner C are its natural companions for repair and surface preparation. Against the wider Indian market, Reebolith S is a fluorosilicate densifier and competes with sodium- and lithium-silicate densifiers and dustproofers from Sika (e.g. Sikafloor densifier/curing-hardener products), MBS, Dr. Fixit and STP, as well as imported sodium-silicate hardeners. Its honest position is as a proven, low-cost, low-skill treatment for utilitarian floors – excellent value for warehouses, workshops and agricultural and food-related floors – but not a substitute for a screed or resin system where the slab is worn out, needs to be rebuilt, or must carry heavy chemical or mechanical loads. Space Arc Engineering, as an authorised Fosroc distributor in Delhi NCR and Pan-India, can supply Reebolith S and benchmark it against these alternatives for a given specification.

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