Fosroc Nitobond SBR20
Single-component styrene butadiene rubber (SBR) latex that bonds new mortar to old concrete, gauges polymer-modified repair mortars, and produces waterproof, freeze-thaw-resistant screeds and renders.
What is it?
A ready-to-use, single-component modified styrene butadiene rubber (SBR) latex emulsion that works both as a slurry bonding bridge and as a gauging additive for site-batched cementitious mortars, screeds and renders.
Where is it used?
Concrete repair and rehabilitation across buildings, water-retaining structures, bridges, parking decks, industrial floors and renders — wherever new cementitious material must bond reliably to an existing substrate.
Why use it?
It chemically and mechanically keys fresh mortar to old concrete, lifts tensile/flexural strength, cuts permeability, and adds water and freeze-thaw resistance — all from one chloride-free liquid that contractors can gauge on site.
How is it applied?
Mixed 1 part SBR : 1 part water : 3 parts cement as a scrubbed-in slurry primer, and dosed at roughly 10 litres per 50 kg cement into the repair mortar, render or screed that is then trowel-applied onto the wet primer.
About Fosroc Nitobond SBR20
Fosroc Nitobond SBR20 is a modified styrene butadiene rubber (SBR) emulsion supplied as a ready-to-use white liquid. It belongs to the Nitobond family of bonding aids and mortar modifiers and is one of the most widely specified latex bonding agents on Indian repair sites. The product performs two roles at once: as a slurry bonding bridge it creates a high-adhesion interface between hardened (old) concrete and freshly placed mortar, and as a gauging liquid it is blended into site-batched mortars, screeds and renders to upgrade their mechanical and durability properties.
Because cementitious mortars are alkaline, repairs made with Nitobond SBR20 continue to protect embedded steel reinforcement against corrosion. The latex is resistant to hydrolysis, so it stays stable in both internal and damp external exposures — a key reason it is used on water-retaining structures, plinths, basements and external renders, not only dry internal patching. It contains no chloride admixtures, which is essential for any application near steel reinforcement.
For Space Arc Engineering’s clients — contractors, structural consultants, architects and procurement teams across Delhi NCR and Pan-India — Nitobond SBR20 is the everyday workhorse for partial-depth concrete repairs, bonding new screeds to old slabs, fixing slip bricks and tiles, and producing waterproof renders. It is the latex counterpart to the epoxy-based Nitobond EP, which is reserved for permanently wet substrates or where a full moisture barrier is required.
The technical insight
The performance of an SBR-modified repair depends far more on the bonding-bridge discipline than on the dosage alone. Nitobond SBR20 is used in two distinct ways and they must not be confused on site. First, as a slurry primer it is mixed at 1 volume SBR : 1 volume clean water : 3 volumes fresh cement, scrubbed hard into a pre-soaked (saturated surface-dry) substrate at roughly 2–3 m² per litre of latex. Second, as a mortar additive it is gauged at about 10 litres per 50 kg of cement (a 3:1 sand:cement mortar). The critical rule is that the repair mortar must go onto the slurry while it is still wet (tacky) — if the bonding bridge skins over or dries, it must be removed and the area re-primed, otherwise the latex film becomes a debonding layer rather than a bond coat. Independent BS 6319 testing of an SBR20-modified 3:1 mortar (28 days, air-cured) records a compressive strength of about 62 MPa, tensile strength of 3.3 MPa, flexural strength of 9 MPa and a slant shear bond of 53 MPa — the elevated tensile and flexural figures are what allow thinner, crack-resistant feather-free sections. The polymer film also bridges micro-pores, which is what delivers the reduced permeability and freeze-thaw resistance, rather than any increase in raw compressive strength.
Where it is used
- Partial-depth (patch) repair of worn, spalled and damaged concrete on horizontal, vertical and overhead surfaces
- Bonding bridge / slurry primer between hardened concrete and fresh repair mortar, screed or render
- Polymer-modified floor screeds and heavy-duty toppings bonded to existing slabs
- Waterproof renders and cementitious slurries for plinths, basements, sumps and water-retaining structures
- Bonding mortar for fixing slip bricks, ceramic tiles and stone to masonry
- Repair of large cracks and reinstatement around exposed, treated reinforcement
- Gauging liquid to improve cohesion, workability and durability of site-batched mortars
Key advantages
- Excellent bond to concrete, masonry, stonework, plaster and blockwork
- Single-component liquid that is easily gauged on site — no two-part mixing
- Contains no chloride admixtures, so it is safe to use around steel reinforcement
- Improved tensile and flexural properties allow thinner, feather-free repair sections
- Produces waterproof, low-permeability repairs, renders and screeds
- High resistance to freeze-thaw cycling and weathering
- Resistant to hydrolysis — suitable for internal and damp external exposure
- Improves mortar cohesion, workability and finishing characteristics
Limitations & considerations
- It is a bonding aid / mortar modifier, not a structural adhesive — use epoxy Nitobond EP where a permanent moisture barrier or substrate/repair separation is needed
- The slurry bonding bridge must be over-coated while still wet; if it dries, it must be removed and re-primed or it becomes a debonding layer
- Mortars must not be applied below 6 mm thickness; single-application build is limited to ~15 mm vertical and up to 40 mm horizontal (or with formwork)
- Not to be applied when temperature is 5°C and falling, or exposed to moving water or heavy rain before final set
- Cementitious materials have only limited chemical resistance — SBR reduces permeability but is not a chemical-resistant lining
- Performance depends heavily on correct surface preparation, saturation (SSD) and curing — poor site discipline undermines bond
- Must be protected from frost in storage; site-batched results vary with sand moisture and material quality
Selection & best practice
Saw-cut and break out the repair to at least 6 mm depth (10 mm at edges to avoid feather-edging), clean to sound concrete, and expose and prime any corroded steel with Nitoprime Zincrich. Pre-soak the substrate to a saturated surface-dry (SSD) condition with no standing water. Mix the bonding slurry at 1 vol SBR20 : 1 vol water : 3 vol fresh cement, scrub it well into the surface, then place the SBR-gauged mortar (about 10 litres SBR per 50 kg cement) onto the slurry while it is still wet — never let the bond coat dry first. Compact by trowel, fully encapsulate exposed reinforcement, keep sections within the recommended thickness, and cure immediately with a Fosroc Concure curing compound or polythene sheeting. In ambient above 35°C, store in shade and mix with cool water; below 5°C use warm water and adopt normal cold-weather precautions.
Specifications
| Chemical base | Modified styrene butadiene rubber (SBR) emulsion, single component |
| Appearance | Ready-to-use white liquid |
| Chloride content | Nil — contains no chloride admixtures |
| Specific gravity | Approx. 1.015 – 1.040 @ 27°C |
| VOC content | 29 g/litre |
| Slurry primer mix ratio | 1 volume SBR20 : 1 volume clean water : 3 volumes fresh cement |
| Typical mortar dosage | Approx. 10 litres SBR20 per 50 kg cement (3:1 sand:cement mortar) |
| Compressive strength (BS 6319, 28 days, air-cured) | 62 MPa |
| Tensile strength (BS 6319, 28 days) | 3.3 MPa |
| Flexural strength (BS 6319, 28 days) | 9 MPa |
| Slant shear bond strength (BS 6319, 28 days) | 53 MPa |
| Slurry primer coverage | Approx. 2 – 3 m² per litre (theoretical) |
| Application thickness | 6 mm minimum; up to 15 mm vertical and up to 40 mm horizontal/with formwork per layer |
| Pack sizes | 20 litre and 200 litre drums (1 litre / 5 litre packs also offered in the India market) |
| Shelf life | 12 months in original unopened packaging, dry storage |
| Storage | Store in a cool, dry place; protect from frost |
Industry use cases
Building repair & rehabilitation
Partial-depth patch repairs of spalled columns, beams, slab soffits and chajjas, bonding new repair mortar to old concrete and re-protecting exposed reinforcement on RCC buildings across Delhi NCR.
Water-retaining & below-grade structures
Waterproof renders and bonding slurries for water tanks, sumps, STP/ETP structures, basements and retaining walls, where the hydrolysis-resistant latex suits permanently damp exposure.
Flooring & screeds
Bonding polymer-modified heavy-duty floor screeds and toppings to existing slabs in warehouses, industrial sheds and parking areas, raising abrasion and crack resistance.
Tiling, cladding & masonry
Bonding mortar for fixing slip bricks, stone cladding and ceramic tiles to concrete and masonry on facades and feature walls.
Infrastructure repair
Repair mortars for bridge sub-structures, culverts and precast elements where chloride-free, freeze-thaw-resistant, low-permeability repairs are specified by consultants.
Frequently asked questions
What is Fosroc Nitobond SBR20 used for?
How is Nitobond SBR20 mixed and dosed?
Does Nitobond SBR20 make concrete waterproof?
What is the coverage of Nitobond SBR20?
Is Nitobond SBR20 safe to use near steel reinforcement?
What is the difference between Nitobond SBR and Nitobond SBR20?
How we position Fosroc Nitobond SBR20
Within the Fosroc system, Nitobond SBR20 is the standard latex bonding aid and mortar modifier, sitting alongside its epoxy stablemate Nitobond EP (specified where a permanent moisture barrier or substrate separation is needed, or for permanently wet substrates) and the acrylic Nitobond AR. On a typical repair it is used with companion Fosroc products — Nitoprime Zincrich for reinforcement priming, Renderoc and Nitomortar repair mortars, and Concure curing compounds — making it a natural fit for Space Arc Engineering’s concrete-repair portfolio. As an authorised Fosroc distributor and applicator, Space Arc supplies and specifies it across Delhi NCR and Pan-India. Among credible alternatives Indian buyers will encounter are Sika Latex / SikaLatex Power and SikaTop bonding products, MYK Laticrete and BASF/MBS (Master Builders Solutions) MasterEmaco bonding agents, Dr. Fixit Pidicrete URP (a comparable SBR latex from Pidilite), and STP (Shalimar/STP) latex bonding aids. Nitobond SBR20 competes on its well-documented BS 6319 performance, chloride-free formulation, and the depth of the surrounding Fosroc repair system; product selection should always be confirmed against the current Fosroc India TDS and project specification.
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