A Guide to the Concrete Repair European Standards BS EN 1504 Series

Introduction

BS EN 1504 – standards for products and systems for the protection and repair of concrete structures – definitions, requirements, quality control and evaluation of conformity provides a comprehensive set of standards for concrete repair.

The 10 documents which form BS EN 1504 are complex and provide information not only to those specifying and applying products but also for the manufacturer.

These guidance notes are aimed to provide information to all those involved with concrete repairs.

This guide extracts the key components of each document relevant to the specifier and applicator in a brief easily understood format. If more detail is required then reference should be made to the relevant standard.

Sika have carried out seminars to applicators and consultants in the UK based on this guide. It is clear that although these documents are to be implemented by 2009, the industry has not fully embraced them.

Hopefully this guide will generate your interest in the standards and prepare you for implementation.

 

Overview of BS EN 1504 Documents

BS EN 1504-9 products and systems for the protection and repair of concrete structures – Definitions, requirements, quality control and evaluation of conformity.

Each standard is commonly sectioned as follows:

• Foreword
• Introduction
• Scope
• Normative reference
• Terms and definitions

These sections should be reviewed by all.

The standards that relate specifically to products and systems and are generally common throughout are:

• Performance characteristics for intended uses
• Requirements

Again these sections should be reviewed by all.

The following sections are specifically aimed at the manufacturer and CE approved inspection body:

• Sampling
• Evaluation of conformity
• Marking and labeling

This guidance document is focused on the terms & definitions, performance characteristics and requirements.

 

BS EN 1504 Principles

There are 11 Corrosion Principles related to Defects in Concrete and Remediation of Reinforcement Corrosion

Defects in Concrete

Principle 1 (PI) Protection against ingress

Principle 2 (MC) Moisture control

Principle 3 (CR) Concrete restoration

Principle 4 (SS) Structural strengthening

Principle 5 (PR) Physical resistance

Principle 6 (RC) Resistance to chemicals

 

Remediation of Reinforcement Corrosion

Principle 7 (RP) Preserving or restoring passivity

Principle 8 (IR) Increasing resistivity

Principle 9 (CC) Cathodic control

Principle 10 (P10) Cathodic protection

Principle 11 (CA) Control of anodic area

 

BS EN 1504-1

BS EN 1504-1 provides terms and definitions used within the standards.

Terms are divided into the following groups:

3.1 General
3.2 Main categories of products and systems
3.3 Main chemical types and constituents of protection and repair products and systems

3.1 Refer to standard.

3.2 Main categories of products and systems

• Anchoring
• Injection products and systems
• Non structural repair products and systems
• Reinforcement protection
• Structural bonding
• Structural repair
• Surface protection systems

3.3 Main chemical types and constituents by protection and repair products and systems

• Additions
• Additives
• Admixtures
• Coatings
• Hydraulic binders (H)
• Hydraulic mortars and hydraulic concretes (CC)
• Hydrophobic impregnations
• Impregnation
• Polymer hydraulic cement mortars or concretes (PCC)
• Polymer mortars and polymer concretes (PC)
• Reactive polymer binder (P)

 

Product Overview for Surface Protection Systems

Hydrophobic Impregnations

• To produce a water repellent surface
• Pores and capillaries internally coated – not filled
• No film or change in concrete appearance
• Silanes or siloxanes

 

Impregnations

• To reduce surface porosity and strengthen the surface
• Pores and capillaries are partially or totally filled
• Discontinuous thin film of organic polymers
• Sodium silicates

 

Coatings

• A continuous protective layer
• Thickness 0.1mm-5.0mm
• Typically organic polymers

 

BS EN 1504-4 covers the following 3 areas of structuring bonding.

• Bonding of external steel or composites to concrete for strengthening purposes
• Bonding of hardened concrete to hardened concrete (precast units)
• Casting of fresh concrete to hardened concrete to form composite bond
• Products suitable for application are polymer mortars or polymer concretes

 

Concrete Injection

BS EN 1504-5 provides guidance on the concrete injection of cracks, voids and interstices in accordance with the following 2 principles.

Principle 1 (PI) Protection Against Ingress

• Filling cracks

Principle 4 (SS) Structural Strengthening

• Injecting cracks, voids or interstices
• Filling cracks, voids or interstices

Objectives of concrete injection

• Achieve impermeability
• Avoid penetration of aggressive agents to avoid corrosion
• Strengthen the structure by strengthening the concrete

 

The injection products are categorised to achieve the following performance conditions

• Force transmitting (F)
  – Transmit forces through product
• Ductile (D)
  – Flexible to accommodate movement
• Swelling (S)
  – Swell repeatedly by water adsorption

 

Injection products – 2 types

• Reactive Polymer Binder (P)
  – 2-3pt Resins
  – Epoxies, polyurethanes, acrylics, polyesters
• Hydraulic Binder (H)
  – Cementitious

 

A general guide to typical injection products used are as follows:

(F) Epoxies, polyesters and cementitious

(D) Polyurethanes and acrylics

(S) Polyurethanes and acrylics

 

Crack widths considered in standard (measured on surface)

• 0.1mm, 0.2mm, 0.3mm, 0.5mm, 0.8mm

 

Anchoring of Reinforcing Steel Bar

BS EN 1504-6 provides guidance on how to anchor steel bars into concrete for structural applications.

Product types

• Hydraulic binders (cementitious)
• Synthetic resins

Product Consistency

• Fluid
• Paste

 

Reinforcement Corrosion Protection

BS EN 1504-7 provides requirements for the protection of existing uncoated steel reinforcement and embedded steel in concrete structures under repair.

The standard does not cover pre-stressing and stainless steels. Coatings are categorised as follows:

Active Coatings

• Electrochemically active pigments
  – Function as inhibitors
  – Localised cathodic protection
• Barrier Coatings
  – Isolate reinforcement from pore water

 

Quality Control and Evaluation of Conformity

BS EN 1504-8 contains information for the manufacture on the following subjects.

• Specifies procedures for quality control and evaluation of conformity
• CE marking and labelling

 

General Principles for the Use of Products and Systems

BS DDENV 1504 defines the principles for protection and repair of concrete structures which have suffered or may suffer damage or deterioration.

The standard also provides guidance on the key stages in the repair and protection process

1. Assessment of defects
2. Identification of the causes of defects
3. Objectives of protection and repair
4. Selection of the appropriate principles and methods
5. Properties of products and systems (1504 parts 2-7)
6. Maintenance management

 

Site Application of Products and Systems and Quality Control of the Works

BS EN 1504-10 recognises the execution of the work is an important and integral part of the protection and repair process. The standard specifies how the work shall be carried out.

For each principle and method covered in the previous standards, there are appropriate clauses in BS EN 1504-10 that covers:

• Preparation
• Application
• Quality

 

Clauses contained in this document can assist in the development of specifications. clauses include:

• Preparation of Concrete
  – Cleaning
  – Roughening
  – Concrete removal
• Preparation of Reinforcement
  – Cleaning
• Application of Products and Systems
  – Bonding
  – Hand applied mortar and concrete
  – Sprayed mortar or concrete
  – Cast mortar or concrete
  – Curing
  – Cracks and Joints
  – Surface Coatings and other treatments
  — Smoothing coatings
  — Surface coatings
  – Anchoring
  – Plate Bonding

 

The previously mentioned clauses are expanded below to highlight the key aspects of the document.

Preparation of Concrete

• GENERAL
  weak, damaged deteriorated, micro-cracked or delaminated concrete removed
• CLEANING
  free from dust, loose material, surface contamination and materials which reduce bond

Techniques

• mechanical, percussion and abrasion
• grit and sand blasting
• water blasting with low pressure up to ~18mpa (2700psi)
• low water volumes up to 60mpa (9000psi)

Roughening

• Appropriate for the products and systems to be applied and shall be specified

Techniques

• Mechanical, percussion and abrasion
• Grit and sand blasting
• Water blasting with high pressure up to 60MPa (9000psi)
• Roughening up to 15mm in depth

Concrete Removal

• Kept to a minimum in accordance with method chosen and shall be specified
• Provide uncontaminated cover on all sides of the reinforcement
• Edges to cut to a minimum angle of 90° and maximum of 135°
• Clearance around corroded reinforcement to substrate – 15.0mm or maximum aggregate size of repair material plus 5.0mm
• Chloride contaminated concrete removed on all sides of corroded rebar for minimum 20mm
• Concrete removal 50mm beyond extent of corrosion along length of bar (from cleaning clause)
• Typing wire fragments, nails and other metal debris removed

Techniques

• Mechanical, percussion
• Hydrodemolition
  – High pressure up to 60MPa (9000psi)
  – Very high pressure up to 110MPa (16500psi)

 

Preparation of Reinforcement

• Extent of any cleaning, coating, removal or replacement shall be specified
• Rust, scale, mortar, concrete, dust and other deleterious material which reduces bond or contribute to corrosion shall be removed
• Whole circumference shall be cleaned
• When contaminated by chlorides, clean by water under low pressure below18MPa (2700psi) unless electrochemical methods of protection and repair are to be used
• For active pigment coatings prepare to SA2
• For barrier coatings prepare to SA2½

 

Application of Products and Systems

Bonding Primer

• Temperature of substrate and repair material should not differ
• Hydrodemolition roughness is greater than any other technique and therefore bonding primer generally not required
• Site adhesion values between repair material and substrate:
  – Structural repair 1.2-1.5MPa
  – Non structural minimum 0.7MPa
• Texture surface of repair material before it has set prior to subsequent layers or apply bonding primer to achieve site adhesion values

 

Hand Applied Mortar and Concrete

• Cementitious systems used without bonding primer shall be pre-wetted but free from surface water
• Mortar is worked well into substrate and compacted without inclusion of entrapped air pockets, so that strength is achieved and reinforcement protected against corrosion

Sprayed Mortar or Concrete

• Sprayed concrete and mortar can be applied by the wet or dry process and shall comply with the relevant standard for sprayed concrete
• Sprayed concrete or mortar should be applied at an angle as close as possible to 90° to the substrate and at a distance of between 0.5 and 1.0m between the nozzle and the substrate

Cast Mortar or Concrete (Flowable)

• Formwork shall be watertight and allow air and bleed water to escape
• Shall not be vibrated

 

Curing

• Comply with ENV 13670-1
• Curing compounds shall not be used where they adversely affect subsequently applied products and systems
• Perforated hoses to feed water to hessian covered with transparent plastic sheeting
• Temperature gradient is as flat as possible to avoid thermal cracking

Cracks and joints

• Filling cracks can be by injection soaking or vacuum techniques
• Before filling any cracks, contamination such as oil or other contaminants must be removed
• Sealing of cracks with bandages may be preferable if cracks are contaminated, too small for filling or if longitudinal and/or shear movements are more than 25% of the crack width
• Cracks may require to be converted into joints if considerable changes in crack width are expected, eg due to thermal effects or structural movement

Surface Coatings

• Smoothing coatings shall be applied and cured to fill uneven surface and surface pores before coatings are applied
• Coatings shall be applied within the specified maximum and minimum thickness

Anchoring

• Anchors shall not be installed in cracked concrete

Plate Bonding

• Plate bonding shall be carried out in accordance with BS EN 1504-4 and any other relevant EN or European Technical Approval

Quality Control Tests and Observations

• 9 control tests are considered

 

CONCLUSIONS

• Full implementation date 2009
• The industry has not embraced documents
• Little demand for CE marked repair products
• For products to conform to BS EN 1504 series they have to be CE marked.
  – Labelling and product data sheets
• Current Sika concrete repair mortar product data sheets integrates the European Standard clauses
• Sika have a Product selector to select products in accordance with the guidelines outlined in BS EN 1504-9 Series