Fosroc Dekguard AC
A one-part, water-based acrylic ester protective and decorative coating that shields reinforced concrete from carbonation, chlorides and UV while letting the structure breathe.
What is it?
Fosroc Dekguard AC is a single-component, water-based acrylic ester protective and decorative coating that dries to a matt, UV-stable film. It is engineered to block atmospheric carbon dioxide and chloride ions from reaching embedded reinforcement, extending the service life of concrete structures.
Where is it used?
Applied to external and internal concrete and masonry surfaces, car parks, bridges, flyovers, building facades, sea walls and structures in coastal and industrial environments across Delhi NCR and Pan-India.
Why use it?
It provides a carbon dioxide diffusion resistance equivalent to over 750mm of concrete cover, resists chlorides, sulphates and UV, remains breathable to water vapour, and being water-based is low-odour and safe for enclosed and occupied areas.
How is it applied?
Surfaces are cleaned and primed; the coating is then brush, roller or airless-spray applied in two coats at 0.2 litres/m2 per coat to achieve a minimum 200 micron wet film, with the second coat applied after the first has cured and within 24 hours.
About Fosroc Dekguard AC
Fosroc Dekguard AC belongs to the well-established Dekguard family of anti-carbonation protective coatings, the water-based member of the range. Carbonation is the slow chemical process in which atmospheric carbon dioxide penetrates concrete, reacts with the alkaline pore solution and lowers its pH. Once the carbonation front reaches the embedded steel, the protective passive layer breaks down and corrosion begins, causing cracking, spalling and loss of structural capacity. Dekguard AC tackles this at source by forming a continuous, low-permeability film over the concrete that dramatically slows the ingress of CO2 and waterborne chlorides while still allowing trapped moisture vapour to escape.
The product is a one-part, acrylic ester coating supplied ready to use as a water-based dispersion. Because it is water-borne rather than solvent-borne, it is low in odour, non-flammable and well suited to enclosed, poorly ventilated or occupied spaces such as basement car parks and internal soffits, conditions where Fosroc’s solvent-based Dekguard S would be less convenient. It cures to a matt, decorative finish that is UV stable, so it resists fading, chalking and embrittlement under the strong Indian sun, and it carries good resistance to a range of aggressive media including chlorides and sulphate ions.
For specifiers in India, Dekguard AC is typically written into concrete repair and durability specifications as the protective topcoat over patch-repaired reinforced concrete, working alongside Fosroc’s Renderoc repair mortars, Galvashield anodes or Nitomortar fairing coats. Space Arc Engineering, as an authorised Fosroc distributor and applicator, supplies and applies Dekguard AC together with its companion primers as a complete protect-and-decorate system for new construction and for refurbishment of carbonation-damaged structures.
The technical insight
The functional heart of Dekguard AC is its CO2 diffusion resistance. Fosroc rates the cured film as equivalent to not less than 750mm of 30 N/mm2 concrete cover, or around 300 metres of equivalent air layer measured by the Taywood method, achieved at the recommended 200 micron minimum wet film thickness over two coats. This very high diffusion resistance to carbon dioxide is what arrests the carbonation front, while the coating’s water vapour permeability remains high enough that the substrate is not sealed against trapped moisture, which would otherwise risk blistering or osmotic failure. This balance, low CO2 transmission combined with adequate breathability, is the defining requirement of EN 1062 / EN 1504-2 anti-carbonation coatings, and it is the property that separates a true anti-carbonation coating from an ordinary decorative masonry paint. The acrylic ester binder also delivers the UV stability and alkali resistance needed to bond durably onto high-pH cementitious substrates without saponifying.
Where it is used
- Anti-carbonation protective and decorative coating for reinforced concrete facades, columns and soffits
- Topcoat over patch-repaired and re-profiled concrete in structural repair systems
- Protection of multi-storey and basement car park structures against carbonation and de-icing chlorides
- Coating of bridges, flyovers and elevated road structures exposed to traffic pollution
- Durability coating for sea walls, jetties and structures in coastal and marine splash zones
- Internal coating in enclosed or occupied areas where a low-odour, non-flammable water-based product is required
- Decorative protective finish on concrete and masonry walls of commercial and industrial buildings
Key advantages
- High carbon dioxide diffusion resistance equivalent to over 750mm of concrete cover, arresting carbonation
- Water-based, low-odour and non-flammable, making it safe for enclosed, occupied and poorly ventilated areas
- UV stable matt finish that resists fading, chalking and degradation in strong sunlight
- Breathable film that allows water vapour to escape, reducing the risk of blistering
- Good resistance to chlorides, sulphate ions and a wide range of chemicals
- One-part, ready-to-use product requiring no on-site mixing of components
- Easily applied by brush, roller or airless spray and readily overcoated for future maintenance
- Both protective and decorative, removing the need for a separate finish coat
Limitations & considerations
- Minimum application and substrate temperature of 10 degrees C must be maintained at all times
- Concrete must be properly prepared by grit blasting or water jetting to remove laitance, in line with ACI 503R-89
- Porous concrete substrates must be pre-wetted to a saturated surface-dry condition before application
- Friable or very porous substrates require priming with Dekguard Primer WB or Dekguard Primer AC to stabilise them
- Not a crack-bridging coating; structures with active or moving cracks need the elastomeric Dekguard Elastic instead
- The second coat must be applied after the first has cured but within 24 hours to ensure intercoat adhesion
- As a thin-film coating it protects against carbonation and chloride ingress but is not a structural repair or waterproofing membrane
- Performance under continuous immersion is limited; consult Fosroc for prolonged immersion conditions
Selection & best practice
Begin with thorough surface preparation: remove all laitance, dust and loose material by grit blasting or water jetting to ACI 503R-89 standards, and fill surface defects with the appropriate Nitomortar or Renderoc fairing product so the coating goes over a sound, even substrate. On porous concrete, saturate the surface with potable water for at least 15 minutes (30 minutes for very porous concrete) and bring it back to a saturated surface-dry condition before coating; prime friable or very porous areas with Dekguard Primer WB or Dekguard Primer AC. Stir the pail thoroughly to redisperse any settlement, then apply two coats at 0.2 litres/m2 per coat to reach the minimum 200 micron wet film, applying the second coat once the first has cured and within 24 hours. Keep substrate and ambient temperatures at or above 10 degrees C, clean tools immediately after use, and verify wet film thickness with a comb gauge during application to guarantee the specified CO2 diffusion resistance is achieved.
Specifications
| Product type | One-part, water-based acrylic ester protective and decorative coating |
| Primary function | Anti-carbonation and anti-chloride protective coating for concrete and masonry |
| Finish | Matt, UV-stable decorative film |
| Specific gravity | Approx. 1.3 at 25 degrees C |
| CO2 diffusion resistance | Equivalent to not less than 750mm of 30 N/mm2 concrete cover (approx. 300 m equivalent air, Taywood method) |
| Coverage | 5 m2/litre per coat at 200 micron wet film thickness (theoretical) |
| Application rate | 0.2 litres/m2 per coat, two coats |
| Wet film thickness | Minimum 200 microns (over two coats) |
| Number of coats | Two coats recommended |
| Application method | Brush, roller or airless spray |
| Recoat interval | After first coat has cured and within 24 hours |
| Minimum application temperature | 10 degrees C |
| Surface preparation standard | Concrete to ACI 503R-89; metal blasted to Swedish Standard SA 2.5 |
| Primers | Dekguard Primer WB or Dekguard Primer AC for friable/very porous substrates |
| Substrates | Concrete, masonry, metal and wood (with appropriate preparation) |
| Flammability | Non-flammable (water-based) |
| Pack size | 20 litre pails |
| Shelf life / storage | 12 months stored in warehouse conditions between 10 and 25 degrees C |
| Cleaning solvent | Fosroc Solvent 102 immediately after use |
Industry use cases
Infrastructure and bridges
Applied as the anti-carbonation topcoat on bridge piers, soffits and elevated road decks to protect reinforcement from CO2 and de-icing or marine chlorides, extending inspection and maintenance cycles.
Car parks and commercial buildings
Used on multi-storey and basement car park structures and on building facades where its low-odour, non-flammable water base allows safe application in enclosed and occupied areas.
Coastal and marine structures
Coated onto sea walls, jetties and coastal building frames in splash and atmospheric zones to resist chloride-driven corrosion in aggressive saline environments.
Concrete repair and refurbishment
Specified as the protective and decorative finish over Renderoc/Nitomortar patch repairs on carbonation-damaged structures, completing a durable repair-and-protect system.
Industrial plants
Applied to concrete columns, walls and structures in industrial facilities exposed to sulphate-bearing and chemically polluted atmospheres for combined chemical and carbonation protection.
Frequently asked questions
Is Fosroc Dekguard AC water-based or solvent-based?
How does Dekguard AC stop carbonation of concrete?
What coverage and film thickness should I specify?
Does Dekguard AC need a primer?
Can Dekguard AC bridge cracks in concrete?
What is the minimum temperature for application in winter?
How we position Fosroc Dekguard AC
Within the Fosroc Dekguard range, Dekguard AC is the water-based anti-carbonation option, sitting alongside the solvent-based Dekguard S and Dekguard Standard, the higher-build Dekguard S300, the crack-accommodating elastomeric Dekguard Elastic for structures with moving cracks, the heavy-duty Dekguard E2000, and the chemical and UV-resistant polyurethane Dekguard PU. For complete durability systems it is most often paired with Fosroc’s Renderoc and Nitomortar repair mortars and Galvashield galvanic anodes. As an authorised Fosroc distributor and applicator, Space Arc Engineering recommends Dekguard AC where a breathable, low-odour, decorative anti-carbonation coating is required, and Dekguard S or Dekguard Elastic where solvent-based performance or crack bridging is needed. Credible alternatives a specifier may evaluate against it include Sika’s Sikagard anti-carbonation coatings (such as Sikagard-550 W Elastic), MBCC/Master Builders Solutions MasterProtect coatings, Dr. Fixit Newcoat and anti-carbonation products from Pidilite, and STP Limited’s protective coating range; Dekguard AC’s advantage lies in Fosroc’s documented CO2 diffusion data and its integration into a single-source concrete repair-and-protect system.
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Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.