Fosroc Brushbond RFX
Two-component acrylic polymer-modified cementitious coating that delivers a flexible, breathable, crack-accommodating waterproof skin on concrete and masonry.
What is it?
A two-component (powder plus acrylic-emulsion liquid) polymer-modified cementitious waterproof coating from Fosroc. It is mixed on site and brushed, rolled or sprayed onto the substrate to form a seamless, flexible, breathable membrane.
Where is it used?
RCC roof slabs and terraces, basements and retaining walls, water tanks and reservoirs, sunken slabs in toilets and bathrooms, balconies, drainage culverts and the external faces of concrete structures exposed to weathering and chloride attack.
Why use it?
It waterproofs while still letting trapped water vapour escape, accommodates minor shrinkage cracks, bonds tenaciously to concrete and masonry without a separate primer, is non-toxic (suitable for potable-water tanks) and needs minimal surface preparation.
How is it applied?
Clean and pre-wet the substrate to a saturated-surface-dry condition, mix the powder into the liquid (adding clean water for brush consistency), then apply a minimum of two coats by stiff brush, roller or spray to build roughly 1 mm wet film, cross-coating the second pass at right angles to the first.
About Fosroc Brushbond RFX
Fosroc Brushbond RFX is one of the most widely specified surface-applied waterproofing coatings on Indian construction sites, and for good reason: it solves the everyday problem of keeping water out of concrete without trapping moisture inside it. The product is a two-component system. One component is a graded cementitious powder; the other is a flexible acrylic polymer emulsion. When the two are blended on site (with a measured addition of clean water to reach brush consistency), they cure into a tough yet elastic film that is chemically and mechanically bonded to the substrate. Because the binder is acrylic-modified rather than a rigid cement slurry, the cured coating flexes with the structure and bridges the fine shrinkage cracks that ordinary cement-based renders cannot tolerate. The “RFX” coating is positioned as the elastomeric, higher-flexibility member of the Fosroc Brushbond family, which also includes the plain Brushbond and Brushbond R grades. For a contractor or consultant in India, the appeal is practical. It is supplied pre-packaged so there is no guesswork over site batching, it goes down with simple tools that any waterproofing crew already owns, it tolerates the saturated-surface-dry concrete that is normal on a monsoon-season pour, and it is non-toxic once cured so it can line drinking-water tanks. It also breathes: the film stops liquid water from entering but allows water vapour to migrate outward, so you avoid the blistering and delamination that plague impermeable coatings applied over green or damp concrete. Architects and engineers value it as a single, well-documented product that can be written into a specification with confidence, while procurement teams value its broad availability and predictable coverage. Space Arc Engineering supplies Brushbond RFX as an authorised Fosroc distributor and applicator across Delhi NCR and Pan-India, with material backed by application guidance so the specified film build is actually achieved on site.
The technical insight
The performance of Brushbond RFX comes from the balance between its cement matrix and its acrylic polymer phase. The cement provides early strength, alkalinity (which passivates embedded steel and resists carbonation) and a mineral bond to the concrete; the acrylic emulsion provides flexibility, adhesion and crack-accommodation, plus a degree of self-curing film formation. Because the two phases co-cure, the membrane behaves less like a paint sitting on the surface and more like a polymer-reinforced cement skin integral to the substrate. This is why adhesion to sound concrete is reported at greater than 1 N/mm and why the coating can accommodate static cracking of the order of 1 mm rather than splitting at the first hairline. The breathable nature is the second key property: the film is closed enough to be waterproof under the modest hydrostatic and wind-driven pressures seen on roofs, tanks and basements, yet open enough to vapour that the structure can dry. The flip side, important to understand, is that a cementitious-acrylic coating is a coating, not a loose-laid sheet membrane, so it relies on a properly prepared, crack-stable, well-detailed substrate. Movement joints, live cracks and re-entrant corners must be detailed and reinforced separately; the coating’s elasticity covers shrinkage cracks, not structural movement. Coverage is governed by the target wet film of about 1 mm built in two coats, which is why a 20 kg-class pack covers roughly 12 to 14 square metres rather than the much larger area a thin decorative paint would claim.
Where it is used
- Waterproofing RCC roof slabs, terraces and chajjas exposed to sun and rain
- Internal and external tanking of basements, retaining walls and lift pits
- Lining of water-retaining structures including overhead and underground water tanks, reservoirs and STP/ETP tanks (non-toxic, potable-water suitable)
- Waterproofing of sunken slabs, shower areas and wet areas in toilets and bathrooms before tiling
- Protective anti-carbonation and anti-chloride coating on the external faces of bridges, chimneys and coastal concrete
- Waterproofing of drainage culverts, channels, balconies and parapet copings
- Refurbishment and re-coating of existing leaking concrete and masonry surfaces
Key advantages
- Waterproof yet vapour-permeable, so trapped moisture can escape and the film resists blistering over damp concrete
- Flexible, elastomeric film that bridges fine shrinkage cracks and moves with thermal expansion close to that of concrete
- Excellent bond to concrete and masonry (adhesion greater than 1 N/mm) with no separate primer required
- Supplied pre-packaged in two components for consistent site mixing and predictable coverage
- Applied with simple tools by brush, roller or spray on horizontal, vertical and overhead surfaces
- Non-toxic when cured, making it suitable for lining potable-water tanks
- Minimal surface preparation and tolerant of saturated-surface-dry substrates
- Provides a barrier against chloride ions, atmospheric acid gases and carbonation, helping protect embedded reinforcement
- Takes light foot traffic and can be over-tiled in wet areas after curing
Limitations & considerations
- It is a surface coating, not a loose-laid sheet membrane, so it depends on a sound, crack-stable, properly detailed substrate
- Accommodates fine static/shrinkage cracks only; live or structural movement cracks and movement joints must be detailed and reinforced separately
- Has a limited pot life (around 30 minutes at 27 C) once mixed, so material must be used promptly and small batches mixed
- Two coats and the correct wet film of about 1 mm are essential; under-application or a single thin coat will not waterproof reliably
- Requires a saturated-surface-dry but not ponded substrate and protection from rain, direct sun and frost during application and initial cure
- Not intended as a standalone wearing surface for heavy or trafficked decks without a suitable screed or protection layer
- Performance on negative-side/high-hydrostatic-pressure applications is limited compared with crystalline or injection systems and should be assessed case by case
Selection & best practice
Achieve the specified result by treating the substrate, not just the coating, as the waterproofing system. Cut out and repair honeycombing, spalls and live cracks with a Fosroc Renderoc repair mortar, form coved fillets at all wall-to-floor junctions, and round off sharp internal corners. Clean the surface free of laitance, oil and loose material, then thoroughly pre-wet it to a saturated-surface-dry condition with no standing water. Mix only as much material as can be used within the pot life, blending the powder into the liquid with a slow-speed drill and paddle to a lump-free, brushable slurry. Apply the first coat firmly to work it into the pores, allow it to set, then apply the second coat at right angles to the first to eliminate pinholes and build the full 1 mm wet film. Reinforce critical zones, pipe penetrations and corners with a fibre/scrim layer bedded into the first coat. Protect the freshly coated surface from rain, direct sun and traffic until cured, then water-test tanks and wet areas before tiling or backfilling. For roofs, finish with a protective screed or tiles where foot traffic is expected.
Specifications
| Product type | Two-component acrylic polymer-modified cementitious waterproof coating |
| Components | Cementitious powder + acrylic polymer emulsion liquid (clean water added on site for brush consistency) |
| Appearance | Slurry that cures to a slightly granular-textured film (typically grey) |
| Mixed density | approx. 1.68 g/cc (brushable consistency) |
| Pot life | approx. 30 minutes at 27 C |
| Application method | Stiff brush, roller, trowel or spray; horizontal, vertical and overhead surfaces |
| Number of coats | Minimum 2 coats (second cross-coated at right angles to the first) |
| Wet film thickness | approx. 1 mm built over two coats |
| Coverage (approx.) | approx. 12-14 m per 20 kg-class pack and approx. 4-4.5 m per 6.71 kg pack at 1 mm |
| Adhesion to concrete | greater than 1 N/mm |
| Static crack accommodation | approx. 1 mm |
| Substrates | Concrete, brick and blockwork; new and existing structures |
| Tested to (standards) | ASTM D4060 (abrasion), ASTM D4541 (pull-off adhesion), ASTM D638 (tensile), ASTM C836 (membrane) |
| Pack sizes | 6.71 kg (5 kg powder + 1.71 kg liquid) and 20.088 kg (15 kg powder + 5.088 kg liquid) |
| Toxicity | Non-toxic when cured; suitable for potable-water tanks |
Industry use cases
Residential and housing
Waterproofing terrace roofs, sunken toilet slabs, balconies and overhead/underground water tanks in apartments and independent homes before tiling or commissioning.
Commercial and institutional buildings
Basement tanking, lift pits and wet areas in malls, hospitals, hotels and offices where a documented, specifiable coating is required by the consultant.
Water and wastewater infrastructure
Lining of reservoirs, clear-water tanks, STP/ETP tanks and channels, using its non-toxic, vapour-permeable membrane on water-retaining concrete.
Coastal and marine-exposed concrete
Anti-chloride and anti-carbonation protective coating on the external faces of structures in Mumbai, Chennai and other coastal belts to slow reinforcement corrosion.
Repair and refurbishment
Re-waterproofing existing leaking terraces, tanks and basements as part of a Renderoc repair-plus-coating system on ageing concrete and masonry.
Frequently asked questions
What exactly is Fosroc Brushbond RFX and how does it work?
Where can Brushbond RFX be used?
How many coats are needed and what coverage should I plan for?
Is it safe for drinking-water tanks?
Can it be applied to a damp surface, and does it stop the concrete from breathing?
Will it bridge cracks in my slab?
How we position Fosroc Brushbond RFX
Within the Fosroc range, Brushbond RFX is the flexible, elastomeric grade of the Brushbond family, sitting above the more rigid Brushbond and Brushbond R coatings; on the same site it is frequently paired with Fosroc Renderoc repair mortars for substrate repair, Nitobond acrylic bonding agents, and Nitoproof or the Proofex sheet-membrane range where a higher-build or loose-laid membrane is needed. As a polymer-modified cementitious coating it is best understood as a brush-applied alternative to crystalline systems and to liquid-applied or sheet membranes, chosen when breathability, easy application and potable-water compatibility matter. Comparable products that Indian specifiers will recognise include Sika’s SikaTop Seal-107 and Sika MonoTop two-component cementitious coatings, Dr. Fixit Pidicrete and LW-plus-style polymer-modified slurry systems from Pidilite, STP (Supreme/Shalimar) cementitious waterproofing coatings, and the MBS / MYK range of acrylic-cement membranes. Against these, Brushbond RFX competes on Fosroc’s strong consultant specification footprint, consistent pre-packaged quality and wide distributor availability rather than on being the lowest-cost option. For applications involving high negative-side hydrostatic pressure or large structural movement, a crystalline admixture/coating or a reinforced sheet/liquid membrane may be more appropriate, and Space Arc Engineering can advise on the right Fosroc system or alternative for the specific exposure as an authorised distributor and applicator serving Delhi NCR and Pan-India.
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