Overview:
This article intends to discuss:
- The standards & repair methods applied on concrete protection according to EN 1504
- Importance of EN 1504 towards the industry as a guide for concrete repair & protection
- Comparison of Dritech’s Dri-Gard Protective Coating Systems with EN 1504 requirements
A Guide for Concrete Protection & Repair
European standard EN1504, entitled: “Products and systems for the protection and repair of concrete structures” is a document that includes guidelines on installing, protecting, and repairing of concrete. These guidelines are based on the individual condition of buildings & structures. The standard comprises 10 parts that are associated to about 65 different standards, corresponding to control of products and systems quality & performance through testing and evaluation of its conformity.
The following is a summary of the different parts in BS EN1504:
- Part 2 and 7 refers to the requirement and specification of the types of systems and products, and their respective testing method
- Part 8 explains the quality control and evaluation of conformity of products and systems and contemplating its “CE” label
- Part 9 states the general application and principles for the utilization of products and systems specified in part 2 to 7
- Part 10 refers to the application of local materials and their quality control
The Importance of EN 1504
It is critical to develop techniques and materials that can improve reinforced concrete (RC) to extend their lifetime cycle. Hence, the EN 1504 standard was developed to help owners and engineers in using suitable materials for concrete protection. It also helps them in creating suitable repair strategies. EN 1054 is adopted by the industry as a guide for concrete repair. It provides complete repair methodology from initial site inspection to the end of works.
All specifications presented in EN 1504 aims to optimize repair operations and provide a valid instrument to correctly identify problems. EN 1504 (Part 9) summarizes 11 concrete repair and protection principles. 6 of its principles address remediation on concrete defects, while the remaining 5 principles relate to preventing reinforcement corrosion.
Furthermore, EN 1504 is used in most major concrete structure projects as it has a broad scope with suitable product performance specifications for structural and non-structural repair according to conditions and requirements of a project. It is also used as a guide by the industry for onsite quality assurance, and to define the site application of these products.
EN 1504-9 Performance Criteria for Protective Coating Systems
EN1504-9 consists of 11 principles & methods for concrete protection and/or repair. The appropriate principles and methods can be chosen based on the condition and requirements of the project.
| Principle | Method |
|---|---|
| Principle 1: Protection against ingress To reduce or prevent the ingress of adverse agents, e.g. water, vapour, chemicals, etc. | – Surface impregnation (penetrating sealer) – Surface coating – Locally bandaged cracks – Filling cracks – Transferring cracks to joints – Erecting external panels (precast concrete) – Applying membranes (plastic or rubber sheets) |
| Principle 2: Moisture control To adjust & maintain moisture content in concrete, as water penetration into concrete may further deteriorate the concrete (e.g. AAR). | – Hydrophobic impregnation (silane/siloxane sealer) – Surface coating – Over-cladding – Erecting external panel – Electrochemical drying treatment |
| Principle 3: Concrete restoration To restore original concrete of an element of the structure to the originally specified shape & function by replacing part of it. | – Hand-apply mortar – Recasting with concrete – Spraying concrete or mortar – Replacing elements |
| Principle 4: Structural strengthening To increase or restore structural load bearing capacity of a structural element. | – Adding/replacing rebars – Installing bonded steel rebars in preformed/drilled holes in concrete – Plate bonding – Adding mortar & concrete – Pre-stressing – Injecting or filling cracks, voids or other interstices |
| Principle 5: Physical resistance To increase resistance to physical or mechanical attack. | – Overlays of coating – Impregnation – Adding mortar or concrete |
| Principle 6: Resistance to chemicals To increase resistance to chemical attacks | – Overlays of coating – Impregnation – Adding mortar or concrete |
| Principle 7: Preserving or restoring passivity To create chemical conditions in which the surface of the reinforcement is maintained in or is returned to a passive condition | – Increasing concrete cover – Replacing contaminated/carbonated concrete – Electrochemical re-alkalization – Re-alkalization of carbonated concrete by diffusion – Electrochemical chloride extraction |
| Principle 8: Increasing resistivity To increase the electrical resistivity of concrete | – Hydrophobic impregnation – Impregnation – Coating |
| Principle 9: Cathodic control To create condition by which cathodic areas of reinforcement are unable to drive an anodic reaction | Limiting oxygen content at the cathode by saturation of surface/surface coating |
| Principle 10: Cathodic protection To create current flow from surrounding concrete to reinforcement steel | Applying electrical potential |
| Principle 11: Control of anodic areas To create condition where anodic reaction of steel is unable to participate in corrosion | – Active coating for reinforcement – Barrier coating – Inhibitor |
Dri-Gard Protective Coating Systems (According to EN 1504)
EN 1504 covers many aspects and topics in relation to concrete protection and repair. In this section, we will compare Dri-Gard systems (Dri-Gard CF 900 System & Dri-Gard AC 800 System) according to the minimum constraints of EN 1504-2 and EN 1504-9.
Dri-Gard CF 900 System
This system consists of Dri-Gard CP 700, hydrophobic silane-siloxane impregnating primer, and Dri-Gard CF 900, solvent-based methylmethacrylate (MMA) anti-carbonation coating.
| Characteristics / Criteria | Min. Requirement (EN 1504-2) | Dri-Gard CF 900 System Test Results | Remarks |
|---|---|---|---|
| Material Type (as per EN 1504-9) | – | Dri-Gard CP 700: Hydrophobic impregnator Dri-Gard CF 900: Barrier coating / surface coating | – |
| Permeability of chloride ions | Subject to national standards (<100 coulombs = negligible) | 0 coulombs with coating | PASS |
| Water absorption | Water absorption <7.5% | 0.07% absorption (immersion for 36 hours) | PASS |
| Permeability to carbon dioxide | Diffusion equivalent air layer thickness, SD > 50m | Diffusion equivalent air layer thickness, SD > 286.3m | PASS |
| Freeze / thaw salt scaling | After thermal cycling, there is no blistering, cracking and delamination | No scaling effect after 50 cycles exposure | PASS |
Dri-Gard AC 800 System
This system consists of Dri-Gard AC 800 Primer, water-based concrete primer, and Dri_Gard AC 800, water-based acrylate anti-carbonation protective coating.
| Characteristics / Criteria | Min. Requirement (EN 1504-2) | Dri-Gard CF 900 System Test Results | Remarks |
|---|---|---|---|
| Material Type (as per EN 1504-9) | – | Barrier coating / surface coating | – |
| Permeability of chloride ions | Subject to national standards (<100 coulombs = negligible) | 22.1 coulombs with coating | PASS |
| Liquid water transmission rate | W < 0.1 kg. m-2. h-0.5 | W = 0.016 kg. m-2. h-0.5 | PASS |
| Permeability to carbon dioxide | Diffusion equivalent air layer thickness, SD > 50m | Diffusion equivalent air layer thickness, SD > 272.3m | PASS |
| Freeze / thaw salt scaling | After thermal cycling, there is no blistering, cracking and delamination | No scaling effect after 50 cycles exposure | PASS |
Please contact Dritech Chemicals Sdn. Bhd. for more information on appropriate protective coating systems for your structures.
Dritech Chemicals Sdn. Bhd.
F-8-3, Jalan SS 7/13A, Plaza Kelana Jaya,
47301, Petaling Jaya, Selangor, Malaysia.
Tel: +6016-618 2178
Fax: +603-8727 1786
Email: info@dritechchemicals.com
by Isaac Chin
(28 Aug, 2021)
