Sika Sikagard-680 MY
Solvent-borne methacrylic protective coating that seals concrete facades against carbonation, chloride ingress and weathering while staying breathable.
What is it?
A one-part, solvent-borne coating built on methacrylic (acrylate) resins that forms a tough, breathable film over concrete and cementitious surfaces, available as a clear glaze or in pigmented shades.
Where is it used?
Exposed concrete facades, precast panels, bridge and flyover elements, and structures in coastal or industrial belts where carbonation and airborne salts attack the cover concrete.
Why use it?
It puts a very high barrier against carbon dioxide (>250 m air-equivalent thickness) and chlorides in front of the reinforcement, slowing carbonation and corrosion while still letting water vapour escape.
How is it applied?
Stir thoroughly and apply two coats by brush or short-pile roller onto sound, dry concrete between +5 C and +35 C, respecting the overcoat interval between passes.
About Sika Sikagard-680 MY
Sikagard-680 MY is Sika’s methacrylic-resin protective coating aimed at one of the most persistent problems on Indian concrete structures: carbonation. Reinforced concrete stays durable only as long as the alkaline cover around the steel holds. Atmospheric carbon dioxide slowly reacts with that cover, drops its pH, and eventually lets the reinforcement corrode and spall the surface. This coating is a single-component, solvent-borne film that sits on the surface and behaves as an anti-carbonation barrier, cutting the rate at which CO2 and chloride can push inward. It is supplied ready to use, either as a colourless clear glaze that refreshes exposed-aggregate and architectural concrete, or as a pigmented top coat in shades such as light grey (RAL 7035), pebble grey and white, with custom colours available on order.
For engineers and consultants, the appeal is that it protects without suffocating the substrate. The film is highly resistant to CO2 diffusion yet remains permeable to water vapour, so trapped moisture is not driven back into the concrete. It resists UV, weathering, alkalis and ageing, and develops a self-cleaning surface that sheds dirt with rainfall, which keeps long-span facades looking maintained between service cycles. Space Arc Engineering stocks and applies Sikagard-680 MY across Delhi NCR and pan-India, and typically specifies it as the finishing barrier layer over a repaired and levelled concrete substrate rather than as a standalone cosmetic paint.
The technical insight
The protection mechanism is diffusion resistance, not sealing by brute thickness. Carbonation advances only as fast as CO2 can migrate through the cover concrete to the carbonation front. By laying a methacrylic film with a CO2 diffusion resistance greater than 250 m equivalent air-layer thickness (tested to BS EN 1062-6, Method B), the coating adds the equivalent of a very deep extra layer of still air in front of the concrete, so the CO2 that would have reached the steel is throttled at the surface. The same continuous film reflects in the durability numbers: chloride-ion diffusion resistance above 90 percent and water absorption reduction above 80 percent at 28 days, with the film unaffected after 50 freeze-thaw cycles under de-icing salts. Critically, the resin chemistry is engineered so that while it blocks CO2 and liquid water, it stays open to water vapour. That asymmetry, high resistance to the aggressive gas and liquid but low resistance to vapour, is what lets a damp Indian substrate keep breathing instead of blistering the coat, and it is the reason a thin two-coat system at roughly 0.15 to 0.20 kg/m2 per coat outperforms a thick, impermeable paint.
Where it is used
- Anti-carbonation protection of RCC facades on high-rise residential and commercial towers
- Protective and decorative coating for precast concrete panels and architectural cladding
- Refresher and protective glaze over exposed-aggregate and board-marked concrete
- Coating of bridge piers, flyover girders and parapets exposed to traffic pollution
- Protection of structures in coastal and marine belts against chloride-laden air
- Facades and external elements in industrial zones with acidic or CO2-rich atmospheres
- Repaired concrete surfaces needing a durable finishing barrier over the patch repair system
- Water-retaining and infrastructure elements where carbonation control is specified
Key advantages
- Very high CO2 diffusion resistance (>250 m air-equivalent) that directly slows carbonation of the cover concrete
- Remains permeable to water vapour, so the substrate breathes and the film resists blistering
- Cuts chloride-ion diffusion by more than 90 percent and water absorption by more than 80 percent at 28 days
- Strong UV, weather, alkali and ageing resistance for long facade service life
- Self-cleaning surface that sheds airborne dirt with rainfall, reducing maintenance washing
- One-part and ready to use, no site mixing of components or catalysts
- Available as clear glaze or pigmented shades, covering both protective and decorative briefs
- Fast handling on site, dust-dry in about 30 minutes and rain-safe after roughly 1 hour at +20 C
Limitations & considerations
- Solvent-borne, so it needs ventilation, fire precautions during use and attention to VOC/odour on enclosed or occupied sites
- Being a surface film it demands a sound, clean, dry and properly prepared substrate; it will not bridge live cracks or hide unrepaired defects
- Application is restricted to a +5 C to +35 C substrate window with relative humidity below 85 percent and rain held off for at least an hour
- Bright yellows and reds need a third coat for full opacity, adding material and a day to the programme
- It is a protective and decorative coating, not a waterproofing membrane or a structural repair mortar
- Full property development takes about 5 days at +20 C, so early exposure or overcoating too soon can compromise the film
Selection & best practice
Treat Sikagard-680 MY as the last layer of a system, not a fix on its own. Repair spalls and honeycombing, level the surface with a suitable Sika repair mortar, and let the substrate reach the required dryness before coating. Clean off laitance, dust, oil and old flaking paint so the film keys properly. Stir the pail thoroughly before and during use. Apply the first coat evenly by brush or short-pile roller at roughly 0.15 kg/m2 for clear glaze or 0.20 kg/m2 for the pigmented top coat, then respect the overcoat interval before the second pass, about 8 hours at +10 C, 5 hours at +20 C and 3 hours at +30 C. Keep the substrate temperature between +5 C and +35 C, work below 85 percent RH, and protect fresh coating from rain for at least an hour. Plan two coats as standard and a third for strong yellows and reds. Allow around 5 days at +20 C for the film to reach full performance before harsh exposure.
Specifications
| Chemical base | One-part solvent-borne methacrylic (acrylate) resin |
| Consumption (clear glaze) | ~0.15 kg/m2 per coat |
| Consumption (pigmented top coat) | ~0.20 kg/m2 per coat |
| CO2 diffusion resistance | >250 m air-equivalent thickness (BS EN 1062-6, Method B) |
| Chloride-ion diffusion resistance | >90% at 28 days |
| Water absorption reduction | >80% at 28 days |
| Solids content | ~43% (varies with colour) |
| Substrate temperature | +5 C min. to +35 C max., RH below 85% |
| Drying / rain resistance | Dust-dry ~30 min; rain-safe after ~1 hr; full cure ~5 days at +20 C |
Industry use cases
High-rise & Commercial Facades
Applied over RCC and precast facade elements on towers to hold back carbonation and keep external concrete looking maintained across long service intervals.
Bridges & Infrastructure
Coats piers, girders and parapets exposed to vehicle exhaust and CO2, extending the time before the reinforcement cover carbonates and corrodes.
Coastal & Marine Structures
Used in chloride-heavy coastal air to cut salt ingress into the cover concrete, protecting steel on jetty buildings, sea-facing facades and shore infrastructure.
Industrial Plants
Protects structural concrete in industrial belts with aggressive, CO2-rich or mildly acidic atmospheres while staying breathable enough for damp substrates.
Architectural & Precast Concrete
Clear glaze refreshes and protects exposed-aggregate and board-marked finishes; pigmented grades give a durable coloured coat on precast cladding panels.
Frequently asked questions
Is Sikagard-680 MY a waterproofing coating?
How many coats are needed and what is the coverage?
Can it be applied over old painted concrete?
Does it let the concrete breathe?
What surface and weather conditions are required for application?
How long does it last and does it need maintenance?
How we position Sika Sikagard-680 MY
Within Sika’s own range, Sikagard-680 MY is the Asia-market sibling of Sikagard-680 S Betoncolor, the widely specified EN 1504-2 methacrylic facade coating; both do the same anti-carbonation job, so the choice usually comes down to regional availability and colour standard. Where the brief calls for a penetrating hydrophobic impregnation rather than a film-forming coat, Sika Sikagard-703 W (silane/siloxane cream) is the better fit, and on structures needing a repair-then-protect sequence it is normally used over Sika MonoTop repair mortars. Across our other brands, Dr. Fixit and MC-Bauchemie offer comparable anti-carbonation and protective coating options where a project is standardised on those systems. If Sika is not mandated, a genuine like-for-like alternative in our Fosroc line is Dekguard, covered below.
Fosroc Dekguard S — Choose the Fosroc Dekguard anti-carbonation coating when the project is standardised on Fosroc systems or when you want a single-source repair-and-protect package alongside Fosroc Renderoc mortars.
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