Dekguard Elastic: Elastomeric Protective Coating for Concrete and Masonry

Overview

Dekguard Elastic is a crack-accommodating elastomeric, pigmented acrylic protective coating system designed to protect concrete and masonry substrates from environmental degradation and corrosive agents. Manufactured by Fosroc International Limited and supplied under license by Parchem, this water-based coating provides comprehensive protection for atmospherically exposed structures in both new and existing applications.

Primary Uses

Dekguard Elastic is formulated to protect atmospherically exposed (non-trafficked) reinforced concrete structures from attack by multiple aggressive agents:

• Acid gases - atmospheric contaminants that degrade concrete surfaces
• Chloride ions - particularly critical in coastal and marine environments
• Oxygen and water - primary drivers of concrete deterioration
• Carbonation - chemical degradation of concrete

The coating is equally suitable for protecting other cementitious substrates and masonry structures, including those in coastal environments, and is compatible with both new and existing structures as part of Fosroc's Renderoc system of concrete reinstatement.

Key Advantages

Elastomeric Properties

• Can accommodate substrate cracking up to 6mm and cyclic movement up to 1mm
• True elastomeric coating with excellent elongation and recovery properties maintained at sub-zero temperatures
• Demonstrates outstanding crack-bridging capabilities across temperature ranges (8mm @ 20°C, 4mm @ 0°C, 1.3mm @ -15°C)

Protective Performance

• Excellent barrier to carbon dioxide, chloride ions, oxygen, and water
• Special acrylic polymer minimizes dirt retention on coating surface
• Allows water vapour to escape from the structure
• UV-resistant with high resistance to long-term weathering effects
• Water-based formulation - environmentally friendly application

Fire and Safety

• Class 1 fire rating (BS 476, Pt 7: 1987) under standard conditions

Technical Composition

Dekguard Elastic comprises a two-component system:

1. Nitoprime DG Primer - A film-forming, stabilizing primer supplied as a clear liquid based on acrylic resin and silane-siloxane dissolved in a penetrating organic carrier. This reactive primer produces a chemically-bound hydrophobic barrier, inhibiting water and water-borne contaminant passage.

2. Dekguard Elastic Coating - An elastomeric, water-based protective coating based on a special acrylic polymer, providing excellent elongation and recovery, low dirt pick-up, and resistance to aggressive environmental elements and UV light.

Performance Specifications

Physical Properties

Property	Typical Result
Volume Solids	49%
Elongation at Break	> 400% (ASTM D412)
Tear Resistance	12 N/mm² (ASTM D624-84)

Protective Capabilities

Protection Type	Performance
Carbon Dioxide Diffusion Resistance	> 150 metres equivalent air thickness; > 380mm equivalent concrete cover
Water Vapour Transmission Resistance	< 1m equivalent air thickness; 1.3 x 10⁻⁴ cm²/sec diffusion coefficient
Water Transmission Resistance	14g/24hr/m²/KPa
Chloride Ion Diffusion Coefficient	5.5 x 10⁻¹⁴ m²/sec @ 147 days
Dynamic Crack Bridging Capability	20,000 cycles @ 20°C (no failure); 15,000 cycles @ 0°C; 4,000 cycles @ -15°C

Application Specifications

Surface Preparation

Surfaces must be dry and free from all contamination:

• Oil, grease, loose particles, decayed matter
• Moss, algal growth, and biological growths
• Laitance (must be removed)
• All traces of mould release oils and curing compounds

Best practice: Light grit-blasting is the recommended surface preparation method to achieve dry, contaminant-free conditions. For moss or algae growth, treat with proprietary biocide after grit-blasting.

Compatibility with Existing Coatings

When application over existing sound coatings or paints is required:

• Trials must be conducted to ensure compatibility and bond retention between underlying coating and substrate
• Bond retention and soundness must be assessed on a trial area
• Performance characteristics may be impaired and fire rating may be invalidated if applied over incompatible coatings
• Consult local Fosroc sales office for guidance

Application Rates and Film Thickness

Parameter	Nitoprime DG	Dekguard Elastic
Number of Coats	Flood coat	2 coats
Theoretical Application Rate per Coat	0.4 litres/m²	0.4 litres/m²
Wet Film Thickness per Coat	N/A	400 microns (minimum)
Total Dry Film Thickness	N/A	400 microns (minimum)
Overcoating Time @ 20°C	2 hours	8 hours

Coverage Data

• Dekguard Elastic: 1.25 m² per litre (total for two coats at 0.4 litres/m² per coat)
• Nitoprime DG: 2.5 m² per litre (total)

Note: Coverage figures are theoretical; practical coverage will be reduced due to wastage factors, low temperature application, and substrate variation.

Alternative Application Method

Under poor drying conditions at low temperatures, three thinner coats (270 microns wet film thickness each) may be applied to achieve better through-drying while maintaining correct dry film thickness recommendations.

Application Methods

Dekguard Elastic may be applied using three techniques:

1. Brush Application - Using suitable brushes
2. Roller Application - For efficient coverage
3. Spray Application - For well-prepared surfaces (no blow holes), providing substantial time savings

Suitable spray equipment includes Graco 795 or Graco 1095 airless spray running at 3000 psi utilizing 19 thou or 21 thou spray tips.

Critical Application Requirements

• Special care at external corners - Must provide unbroken coating at external corners and similar exposed protrusions to ensure complete coverage
• Surfaces with blowholes - Should first be filled using Renderoc FC or Renderoc ST 06 (cementitious fairing coat), allowed to cure approximately 48 hours before Dekguard Elastic application
• Two-coat application - Essential to achieve proper protective performance and crack accommodation capability

Temperature and Environmental Limitations

Application Temperature Requirements

• Nitoprime DG: Application should not commence if substrate temperature is below 2°C
• Dekguard Elastic: Application should not commence if substrate temperature is below 5°C
• Application rates reduce significantly at temperatures below 10°C

Environmental Conditions to Avoid

• Frost exposure: Do not apply where likelihood of frost exposure exists within 48 hours
• Windy conditions: Avoid early-age dust adhesion
• Rainfall: Not applicable within 2 hours at 20°C or 20 hours at 5°C (up to 80% RH)
• High humidity: Do not apply when relative humidity exceeds 90%

Limitations

General Constraints

• Not suitable for ponded water exposure - Dekguard Elastic should not be considered for areas subjected to exposure to ponded water; Dekguard S should be considered instead
• Not for trafficable surfaces - Dekguard coatings are not designed nor suitable for use on traffic-bearing surfaces
• Fire rating invalidation - Fire rating may be invalidated when applied over existing coatings or paints

Surface Protection Requirements

The following elements must be protected during application:

• Glass areas (masked)
• Plants and grass
• Joint sealants
• Asphalt and bitumen-painted areas

Product Supply and Packaging

Product Code	Description	Container Size
FC860600-15L	Dekguard Elastic White	15 litres
FC860621-15L	Dekguard Elastic Special Colour	15 litres
FC860633-15L	Dekguard Elastic In Can Tint	15 litres
FC862600-20L	Nitoprime DG	20 litres
FC600800-4L	Fosroc Solvent 10	4 litres
FC600800-20L	Fosroc Solvent 10	20 litres

Available Colours

• White
• Special Colours
• In-Can Tint formulations for custom colour applications

Storage and Handling

Storage Conditions

• Store in cool, dry conditions
• Protect from frost - Dekguard Elastic must be protected from frost during storage
• Store in original, unopened containers

Cleaning and Maintenance

• Dekguard Elastic: Remove from tools and equipment with clean water immediately after use
• Nitoprime DG: Remove from tools and equipment using Fosroc Solvent 10

Important Note: Fosroc Solvent 10 is used only for Nitoprime DG removal, not for Dekguard Elastic cleaning.

Typical Material Properties Achieved

The Dekguard Elastic system applied at minimum recommended application rates achieves the following protective performance characteristics that make it particularly valuable for coastal environments and structures at risk from chloride ion ingress and carbonation degradation.

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References

• [1] Fosroc_Dekguard_Elastic_TDS.pdf
• [5] Fosroc_Nitoprime_DG_TDS.pdf
• [6] Fosroc_Dekguard_Primer_TDS.pdf