Sika Latex SBR
A single SBR latex that works as a bonding coat, a waterproofing admixture and a mortar toughener — the site-mix polymer engineers reach for on screeds, sunken slabs and repair work.
What is it?
A milky-white styrene-butadiene rubber (SBR) latex emulsion that is blended into cement slurries, mortars, plasters and grouts to raise adhesion, cut water permeability and add flexibility.
Where is it used?
Sunken slabs, roof slabs, basements, water tanks, retaining walls and sunshades for waterproofing; and bonding coats between old and new concrete, screeds and repair patches.
Why use it?
One product handles bonding, waterproofing and mortar modification, so a contractor carries a single drum instead of three separate chemistries — and it dilutes up to six times, so a little goes a long way.
How is it applied?
Dilute with water to a gauging solution at the ratio for the job, mix into cement or cement-sand, then brush, trowel or cast within roughly 20-30 minutes of mixing.
About Sika Latex SBR
Sika Latex SBR is Sika India’s workhorse styrene-butadiene polymer for the three jobs that turn up on almost every wet-area or repair project: getting new mortar to grip old concrete, keeping water out of the structure, and making a site-batched mortar tougher and less prone to cracking. It is fully water-soluble, so it is not painted on neat — it goes into the gauging water and travels through the mix, which is why the same drum can serve a bonding slurry in the morning and a waterproof plaster in the afternoon. For contractors used to juggling a separate bonding agent, a separate integral waterproofer and a separate polymer modifier, that consolidation is the real appeal.
The chemistry is deliberately forgiving. Because the SBR film cures alongside the cement rather than replacing it, the finished mortar behaves like a slightly rubberised cement mortar rather than a resin — it stays vapour-permeable, tolerates ordinary site handling, and cleans up with water while fresh. That makes it a sensible default for the bulk of residential and commercial waterproofing and patch-repair work across Delhi NCR. Where it stops is honest and worth stating up front: it is not an epoxy, so for high-stress structural bonding or permanently submerged, aggressive-exposure situations you step up to a dedicated system. For the everyday 80 percent, though, Sika Latex SBR is the practical, cost-effective choice.
The technical insight
The performance comes from how the SBR latex behaves inside a curing cement matrix. As the mortar hydrates and loses water, the styrene-butadiene particles coalesce into a continuous polymer film that threads through and around the cement gel, bridging the fine capillary pores that would otherwise carry water and dissolved salts. That pore-blocking is what delivers both the waterproofing and the improved resistance to salt permeation and leaching. The same polymer film adds tensile ductility, so the hardened mortar flexes a little under stress instead of cracking — and it wets out the substrate far better than plain cement slurry, which is why a Latex-modified bonding coat achieves concrete-failure adhesion (tensile bond of at least 1.5 N/mm² to EN 1542, meaning the concrete gives way before the bond does). Because the polymer also reduces the water needed for a given workability, the base mortar ends up denser and stronger as a bonus. Two rules protect all of this: the mix must be kept continuously stirred so cement does not settle out of the latex, and it must be cured slowly under cover, since rapid drying skins the polymer before it can knit into the matrix.
Where it is used
- Waterproof coating for sunken slabs, roof slabs, basements, water tanks, retaining walls and sunshades
- Bonding coat between old set concrete and fresh concrete or screed at cold joints
- Bonding slurry ahead of repair mortars, plasters and rendering layers
- Polymer-modified repair mortars for spalled or honeycombed concrete
- Waterproof plaster and dense render for bathrooms, toilets, kitchens and external walls
- Screeds and floor toppings that must bond monolithically to the base slab
- Treatment against leaching and saltpetre (efflorescence) action on masonry
- Low-viscosity cement injection grout for crack sealing and non-structural filling
Key advantages
- Genuine multipurpose use — one polymer covers bonding, waterproofing and mortar modification
- Achieves concrete-failure bond strength (tensile adhesion of at least 1.5 N/mm² to EN 1542)
- Cuts water and salt permeability, improving resistance to leaching and saltpetre
- Adds toughness and flexibility, reducing shrinkage and stress cracking in mortars
- Bonds reliably to concrete, stone, brick and other common substrates
- Dilutes with water up to six times, so consumption per square metre stays economical
- Water-based and low-odour; tools and fresh spills clean up with plain water
- Stocked in pack sizes from 250 g up to 100 kg, suiting patch jobs and large sites alike
Limitations & considerations
- Not an epoxy — unsuitable for high-stress structural bonding or heavy-duty load transfer where a Sikadur epoxy is required
- SBR films are not designed for permanent immersion in aggressive or chemically loaded water; specify a dedicated membrane for those cases
- Never brush neat latex or a latex-water mix onto the substrate as a bond coat — cement and sand must be added, or the bond fails
- Short working window (about 20-30 minutes at 30°C) demands that mixing and application be closely sequenced
- Needs disciplined slow curing under cover for 3-5 days; rapid drying in sun or wind compromises the polymer film
- Performance depends on sound, clean, mechanically keyed and pre-saturated substrates — poor preparation undoes the product
Selection & best practice
Prepare first: the substrate must be sound, clean and free of laitance, dust, oil and old coatings, mechanically roughened where smooth, and pre-saturated to a saturated-surface-dry (dark matt, no glistening water) state at least a couple of hours before you start. Mix the latex into the correct volume of water to make the gauging solution, then add cement or cement-sand while stirring slowly to a smooth, lump-free consistency — hand-mix or use a low-speed drill for no more than two minutes, and keep stirring throughout use so cement does not settle. Follow the job ratio: bonding coat and waterproof coating at SBR:water:cement 1:4:8, polymer mortar or waterproof plaster at 1:4:8:32 laid no thicker than 20 mm per pass. For waterproofing apply at least two coats crosswise, three where water penetration is severe, and reinforce with Sika Fabric-50 between coats on demanding areas. Work in the shade, out of strong wind, protect fresh work from rain, then cure slowly under polythene, wet hessian or Sika Antisol for 3-5 days and do not pond water before five days.
Specifications
| Chemical base | Styrene butadiene rubber (SBR) latex emulsion |
| Appearance / colour | Liquid / milky white |
| Specific gravity | ~1.02 |
| pH value | 8 ± 1 |
| Tensile adhesion strength | ≥ 1.5 N/mm² (concrete failure) to EN 1542 |
| Bonding coat consumption | ~350 g/m² mixture (~30 g/m² Sika Latex SBR), single coat |
| Waterproof coating consumption | ~900 g/m² mixture (~70 g/m² Sika Latex SBR), two coats |
| Application temperature | +5°C min to +40°C max (air and substrate); ~20-30 min working time at +30°C |
| Packaging | 250 g, 500 g, 1 kg, 5 kg, 10 kg, 20 kg and 100 kg containers |
| Shelf life & storage | 18 months in sealed pack, stored +5°C to +35°C, protected from frost and direct sun |
Industry use cases
Residential wet areas
Waterproof plaster and coating for bathrooms, toilets, kitchens and sunken slabs, plus bonding of new plaster to old walls during renovation.
Water-retaining structures
Internal and external waterproofing of overhead and underground water tanks, retaining walls and basements where salt permeation and leaching are concerns.
Concrete repair & rehabilitation
Latex-modified patch mortars and bonding slurries for spalled columns, beams and slabs, giving fresh repair mortar a concrete-failure grip on the parent substrate.
Flooring & screeds
Bonding coats that lock cement screeds and floor toppings monolithically to base slabs, preventing hollowness and delamination.
Building envelope & masonry
Dense external renders and anti-efflorescence treatment on brick and block walls to control saltpetre staining and driving-rain penetration.
Frequently asked questions
Can I apply Sika Latex SBR neat, straight onto the concrete, as a bonding agent?
How much water do I mix it with?
How many coats do I need for waterproofing, and how long between them?
Is Sika Latex SBR strong enough for structural concrete repair?
What pack sizes and shelf life should I plan around?
How long must the finished work cure before I flood-test a tank or slab?
How we position Sika Latex SBR
Sika Latex SBR is the general-purpose choice within Sika’s polymer range; where the exposure is tougher, step within the same family — Sikadur epoxy systems (for example Sikadur-31 IN) for structural bonding and crack sealing, Sika MonoTop-108 Water Plug for active leaks, Sika Fabric-50 to reinforce a waterproofing coat, and Sika Antisol as the matching curing compound. As an authorised distributor for multiple brands, Space Arc can also line it up against Fosroc’s Nitobond SBR or Dr. Fixit and MC-Bauchemie equivalents so specifiers pick on approved-vendor lists and price, not just habit.
Fosroc Nitobond SBR — A closely equivalent SBR bonding-and-waterproofing latex — specify it when the project’s approved-vendor list or client standard calls for Fosroc rather than Sika.
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