EN1504 & Protective Coating Selection for Concrete Structures

OVERVIEW:
This article is intends to discuss:

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 based on the individual condition of buildings. 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:

N1504 acts as a guide to ensure proper material selection and application methods are used for protection and repair of concrete structures.


The Importance of EN1504

It is critical to develop techniques and materials that can improve reinforced concrete (RC) in terms of its mechanical & functional characteristics, and to extend their lifetime cycle. Hence, the guidelines in EN 1504 have been developed to assist owners and engineers in using suitable materials for concrete protection and creating suitable repair strategies. It is adopted by the industry as a guide for concrete repair as it provides complete repair methodology from initial site inspection to the end of works.

All the specifications presented in BS 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. Six of the principles address remediation on concrete defects, while the remaining five relates to preventing reinforcement corrosion.

Furthermore, EN 1504 is used by most of the industry for major concrete projects due as it has a broad scope that provides engineers 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 guidance by the industry for onsite quality assurance, and to define the site application of these products.


EN1504-9 Performance Criteria for Protective Coating Systems

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 an element of a structure	– 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 attack	– Overlays of coating – Impregnation – Adding mortar or concrete
Principle 7 Preserving or restoring passitivity 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 the 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 fo steel are unable to participate in corrosion	– Active coating for reinforcement – Barrier coating – Inhibitor

EN1504 acts as a guidance by the industry for onsite quality assurance, and to define the site application of these products, including protective coatings.


Dri-Gard Protective Coating Systems
(According to EN1504)

• EN1504 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 EN1504-2 and EN1504-9.

> 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.

Summary of Dri-Gard CF 900 System [Full test report available here]

> Dri-Gard AC 800 System

• This system consists of Dri-Gard AC 800 Primer, water-based primer, and Dri-Gard AC 800, water-based acrylate protective coating.

Summary of Dri-Gard AC 800 System [Full test report available here]

Please contact us for more information on appropriate protective coating systems for your structures.

by Isaac Chin
[28 August, 2021]