Electrochemical realkalization and chloride extraction treatments for reinforced concrete - Part 2: Chloride extraction

This document specifies a procedure for carrying out impressed current electrochemical chloride extraction from chloride bearing concrete in existing structures. It is applicable to atmospherically exposed parts of structures with ordinary reinforcement and/or post-tensioned tendon ducts embedded in concrete. In the latter case, it is essential to verify that there is no risk of hydrogen embrittlement, if necessary by conducting trials and installing monitoring during the treatment.
This document does not apply to concrete containing pre-stressing steel which can suffer hydrogen embrittlement during chloride extraction, or to concrete containing epoxy-coated or galvanized reinforcement.
In case of post-tensioned, pre-stressing concrete, the endangered tendon strands may be shielded by the tendon ducts from unwanted and/ or exceeded polarization into the cathodic range and respective water reduction.

Elektrochemische Realkalisierung und Chloridextraktionsbehandlungen für Stahlbeton - Teil 2: Chloridextraktion

Dieses Dokument legt ein Verfahren zur elektrochemischen Chloridextraktion aus chloridhaltigem Beton in bestehenden Bauwerken mittels Fremdstrom fest. Es ist anwendbar an atmosphärisch exponierten Bauteilen von Bauwerken, welche normal bewehrt oder als Spannbeton mit nachträglichem Verbund ausgeführt sind. Im letztgenannten Fall ist es erforderlich zu prüfen, dass keine Gefahr von Wasserstoffversprödung besteht; falls notwendig kann dies durch die Durchführung von Probeläufen und die Installation von Überwachungsgeräten während der Behandlung erreicht werden.
Dieses Dokument ist nicht anwendbar auf Beton mit vorgespannter Bewehrung, die während der Chloridextraktion der Wasserstoffversprödung unterliegen kann, oder auf Beton mit Epoxidharz-beschichtung oder galvanisierter Bewehrung.
Im Fall von Spannbeton mit nachträglichem Verbund können gefährdete Spannglieder durch deren Lage im Hüllrohr vor unerwünschter und/oder zu starker kathodische Polarisation und entsprechender Wasser-reduktion geschützt sein.

Réalcalinisation électrochimique et traitements d'extraction des chlorures applicables au béton armé - Partie 2 : Extraction des chlorures

Le présent document spécifie une procédure d’extraction électrochimique par courant imposé des chlorures contenus dans des bétons d’ouvrages existants. Il est applicable à des éléments de structure exposés au milieu ambiant contenant des armatures ordinaires et/ou à des gaines de câbles de post-tension noyées dans le béton. Dans le dernier cas, il est essentiel de vérifier qu’il n’y a pas de risque de fragilisation due à l’hydrogène, en réalisant si nécessaire des essais et en assurant une surveillance pendant le traitement.
Le présent document ne s’applique ni au béton contenant des aciers de précontrainte qui peuvent subir une fragilisation due à l’hydrogène lors de l’extraction des chlorures, ni au béton contenant des armatures revêtues époxy ou galvanisées.
Dans le cas du béton précontraint par post-tension, les torons menacés peuvent être protégés par des gaines contre la polarisation indésirable et/ou excessive dans le domaine cathodique et contre la réduction de l’eau associée.

Elektrokemična realkalizacija in postopki kloridne ekstrakcije za armirani beton - 2. del: Kloridna ekstrakcija

General Information

Status
Published
Public Enquiry End Date
14-Sep-2018
Publication Date
11-Nov-2020
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
29-Oct-2020
Due Date
03-Jan-2021
Completion Date
12-Nov-2020

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SLOVENSKI STANDARD
SIST EN 14038-2:2020
01-december-2020
Nadomešča:
SIST-TS CEN/TS 14038-2:2012

Elektrokemična realkalizacija in postopki kloridne ekstrakcije za armirani beton - 2.

del: Kloridna ekstrakcija

Electrochemical realkalization and chloride extraction treatments for reinforced concrete

- Part 2: Chloride extraction

Elektrochemische Realkalisierung und Chloridextraktionsbehandlungen für Stahlbeton -

Teil 2: Chloridextraktion

Réalcalinisation électrochimique et traitements d'extraction des chlorures applicables au

béton armé - Partie 2 : Extraction des chlorures
Ta slovenski standard je istoveten z: EN 14038-2:2020
ICS:
91.100.30 Beton in betonski izdelki Concrete and concrete
products
SIST EN 14038-2:2020 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 14038-2:2020
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SIST EN 14038-2:2020
EN 14038-2
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2020
EUROPÄISCHE NORM
ICS 91.100.30 Supersedes CEN/TS 14038-2:2011
English Version
Electrochemical realkalization and chloride extraction
treatments for reinforced concrete - Part 2: Chloride
extraction

Réalcalinisation électrochimique et traitements Elektrochemische Realkalisierung und

d'extraction des chlorures applicables au béton armé - Chloridextraktionsbehandlungen für Stahlbeton –

Partie 2 : Extraction des chlorures Teil 2: Chloridextraktion
This European Standard was approved by CEN on 14 September 2020.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this

European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references

concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN

member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by

translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management

Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and

United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATIO N
EUROPÄISCHES KOMITEE FÜR NORMUN G
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 14038-2:2020 E

worldwide for CEN national Members.
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SIST EN 14038-2:2020
EN 14038-2:2020 (E)
Contents Page

European foreword ....................................................................................................................................................... 4

Introduction .................................................................................................................................................................... 5

1 Scope .................................................................................................................................................................... 6

2 Normative references .................................................................................................................................... 6

3 Terms and definitions ................................................................................................................................... 6

4 Principle ............................................................................................................................................................. 7

5 General ................................................................................................................................................................ 7

5.1 Quality management systems ..................................................................................................................... 7

5.2 Personnel ........................................................................................................................................................... 7

6 Assessment and repair of the structure .................................................................................................. 8

6.1 General ................................................................................................................................................................ 8

6.2 Review of records ............................................................................................................................................ 8

6.3 Inspection .......................................................................................................................................................... 8

6.4 Assessment of corrosion activity ............................................................................................................... 9

6.5 Determination of chloride content ........................................................................................................... 9

6.6 Visual inspection of the rebar surface and carbonation depth measurement ......................... 9

6.7 Concrete cover thickness and reinforcement location measurements .................................... 10

6.8 Alkali aggregate reaction .......................................................................................................................... 10

6.9 Reinforcement continuity and size ........................................................................................................ 10

6.10 Repair ............................................................................................................................................................... 10

6.10.1 General ............................................................................................................................................................. 10

6.10.2 Concrete removal ......................................................................................................................................... 10

6.10.3 Reinforcement preparation ..................................................................................................................... 11

7 Materials and equipment .......................................................................................................................... 11

7.1 Calibration of instrumentation ............................................................................................................... 11

7.2 Anode system ................................................................................................................................................. 11

7.2.1 General ............................................................................................................................................................. 11

7.2.2 Anode ................................................................................................................................................................ 11

7.2.3 Anode zone ..................................................................................................................................................... 11

7.2.4 Alkaline electrolyte solution .................................................................................................................... 11

7.3 Electric cables ................................................................................................................................................ 12

7.4 Power supply ................................................................................................................................................. 12

8 Installation procedures ............................................................................................................................. 13

8.1 Electrical continuity .................................................................................................................................... 13

8.2 Other metallic parts within the treatment area ................................................................................ 13

8.3 Performance monitoring ........................................................................................................................... 13

8.4 Installation of the anode system ............................................................................................................. 13

8.5 Protection of electrolyte solution .......................................................................................................... 13

8.6 Electrical installation .................................................................................................................................. 13

8.7 Preliminary testing and documentation ............................................................................................. 14

9 Commissioning, operation and termination of treatment ............................................................ 14

9.1 Visual inspection .......................................................................................................................................... 14

9.2 Safety precautions ....................................................................................................................................... 14

9.3 Energizing and adjustment of current output ................................................................................... 14

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SIST EN 14038-2:2020
EN 14038-2:2020 (E)

9.4 Routine inspection and maintenance .................................................................................................... 15

9.5 Chloride extraction process monitoring .............................................................................................. 15

9.6 Termination of treatment .......................................................................................................................... 15

10 Final report ..................................................................................................................................................... 17

11 Post-treatment coating and monitoring ............................................................................................... 18

Bibliography ................................................................................................................................................................. 19

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SIST EN 14038-2:2020
EN 14038-2:2020 (E)
European foreword

This document (EN 14038-2:2020) has been prepared by Technical Committee CEN/TC 219 “Cathodic

protection”, the secretariat of which is held by BSI.

This European Standard shall be given the status of a national standard, either by publication of an

identical text or by endorsement, at the latest by April 2021, and conflicting national standards shall be

withdrawn at the latest by April 2021.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

This document supersedes CEN/TS 14038-2:2011.

EN 14038, Electrochemical realkalization and chloride extraction treatments for reinforced concrete is

currently composed of the following parts:
— Part 1: Realkalization;
— Part 2: Chloride extraction.
In comparison with CEN/TS 14038-2:2011, the following changes have been made:
a) Clause 2 “Normative references” has been revised;

b) Clause 4 “Principle”, Clause 6 “Assessment and repair of the structure” has been revised;

c) 7.2.2 “Anode” has been complemented by requirements for the used anodes;
d) Requirements for anode zones have been added to 7.2.3 “Anode zone”;
e) A note has been added to 7.4 “Power supply”;
f) Clause 8 “Installation procedures” has been revised;

g) Clause 9 “Commissioning, operation and termination of treatment” has been revised, especially 9.6

“Termination of treatment”;

h) Clause 10 “Final report” and Clause 11 “Post-treatment coating and monitoring” have been revised;

i) Bibliography has been supplemented with several publications;
j) Document has been revised editorially.

According to the CEN-CENELEC Internal Regulations, the national standards organisations of the

following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,

Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,

Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of

North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the

United Kingdom.
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SIST EN 14038-2:2020
EN 14038-2:2020 (E)
Introduction

The purpose of chloride extraction is to rehabilitate a reinforced concrete part from corrosion activity

non-destructively and to provide long term corrosion protection of steel reinforcement in concrete

which has been affected by chloride. The duration of the treatment is from several weeks up to as much

as several months, depending on the amount and ingress depth of accumulated chloride, the

permeability of the concrete, the layout of the reinforcement and other factors.

NOTE Based on experience, in case of a cover thickness of 30 mm to 40 mm and a concentration of chloride in

the cover zone, an ECE can be done successfully in a one-stage treatment of 4 to 6 weeks.

There are other electrochemical procedures that can be used to provide corrosion protection to steel in

concrete structures. These include cathodic protection and re-alkalization. There are European

standards for cathodic protection of steel in concrete (EN ISO 12696) and for the re-alkalization of

carbonated concrete (EN 14038-1).

It has been assumed in the drafting of this document that design and execution of a chloride extraction

application will be entrusted to appropriately qualified, competent and experienced people, for whose

use it has been prepared.
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SIST EN 14038-2:2020
EN 14038-2:2020 (E)
1 Scope

This document specifies a procedure for carrying out impressed current electrochemical chloride

extraction from chloride bearing concrete in existing structures. It is applicable to atmospherically

exposed parts of structures with ordinary reinforcement and/ or post-tensioned tendon ducts

embedded in concrete. In the latter case, it is essential to verify that there is no risk of hydrogen

embrittlement, if necessary by conducting trials and installing monitoring during the treatment.

This document does not apply to concrete containing pre-stressing steel, which can suffer hydrogen

embrittlement during chloride extraction, or to concrete containing coated or galvanized reinforcement.

In case of post-tensioned, pre-stressing concrete, the endangered tendon strands can be shielded by the

tendon ducts from unwanted and/or exceeded polarization into the cathodic range and respective

water reduction.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

EN 1504-2, Products and systems for the protection and repair of concrete structures - Definitions,

requirements, quality control and evaluation of conformity - Part 2: Surface protection systems for

concrete

EN 1504-9, Products and systems for the protection and repair of concrete structures - Definitions,

requirements, quality control and evaluation of conformity - Part 9: General principles for the use of

products and systems

EN 14629, Products and systems for the protection and repair of concrete structures - Test methods -

Determination of chloride content in hardened concrete

EN 14630, Products and systems for the protection and repair of concrete structures - Test methods -

Determination of carbonation depth in hardened concrete by the phenolphthalein method

EN ISO 8044, Corrosion of metals and alloys - Vocabulary (ISO 8044)
EN ISO 12696:2016, Cathodic protection of steel in concrete (ISO 12696:2016)
3 Terms and definitions

For the purposes of this document, the terms and definitions given in EN ISO 8044 and EN 1504-2 and

the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
3.1
chloride extraction

electrochemical treatment for providing a low chloride content and developing a high pH value to

concrete which surrounds reinforcing bars, corresponding to sound, carbonated or non-carbonated

concrete
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SIST EN 14038-2:2020
EN 14038-2:2020 (E)
4 Principle

Electrochemical Chloride extraction (ECE) of reinforced concrete is performed by applying an electric

field between the steel reinforcement embedded in the concrete and an anode surrounded by an

alkaline electrolyte solution. The anodes are placed temporarily on the concrete surface. Dissolved,

negatively charged ions – such as chloride – will be moved from the reinforcement to the external

electrode. This is a physical process, controlled by the applied voltage.

Coincidentally, the electrochemical reactions occurring at the steel surface provide the evolution of

hydroxyl ions by the reduction of oxygen and water. This process alkalizes the concrete in the vicinity of

the rebar as described in EN 14038-1 and is in correlation with the flowing current.

The chloride content will not be reduced to zero; the usual target content is an average profile of 0,4 %,

related to the cement mass. To achieve this, the driving voltage between reinforcement and the external

anode should be set as high as possible, but not exceeding safety limits.

NOTE 1 The chloride extraction effect is not limited to the zone between concrete surface and next

reinforcement layer, but can be triggered in greater depths of concrete, as long as reinforcement is present and is

connected with the upper reinforcement layer. In such a case, a multi-stage treatment is required. Treatments

from the opposite side of a concrete slab are possible, but will need an extended time of application.

If the reinforcement surface is covered by corrosion products, these oxides will have to be reduced

prior to the possible reduction of oxygen and water. During this period which can consume theoretically

up to 700 Ah/m , few if any hydroxyl ions can be developed. In such a case, hydrogen evolution is

unlikely, and high initial currents can be tolerated.

NOTE 2 Details of the principles underlying this process are given in the European Federation of Corrosion

report [1] and in a more recent publication [2]. Fundamental research reports on ECE have been published in [5]

to [8].

NOTE 3 Some electrolyte materials can change the surface appearance of the concrete.

5 General
5.1 Quality management systems

The design, the installation, the energizing, the commissioning, the long-term operation of all of the

elements of electrochemical chloride extraction systems for steel in concrete shall be fully documented.

NOTE EN ISO 9000 constitutes a suitable Quality Management Systems Standard, which can be utilized.

Each element of the work shall be undertaken in accordance with a fully documented quality plan. Each

stage of the design shall be checked and the checking shall be documented. Each stage of the

installation, energizing, commissioning and operation shall be the subject of appropriate visual,

mechanical and/or electrical testing and all testing shall be documented.

All test instrumentation shall have valid calibration certificates traceable to national or European

Standards of calibration.
The documentation shall constitute part of the permanent records for the works.
5.2 Personnel

Each aspect of the ECE system design, installation, testing of the installation, energizing, commissioning

and long-term operational control shall be under the supervision of persons with appropriate

qualification, training, expertise and experience in the particular element of the work for which they are

responsible.
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SIST EN 14038-2:2020
EN 14038-2:2020 (E)

ECE of steel in concrete is a specialist multidiscipline activity. Expertise is required in the fields of

electrochemistry, concrete technology, civil and/or structural engineering and cathodic protection

engineering.

Persons who undertake the design, supervision of installation, commissioning, supervision of operation,

measurements, monitoring and supervision of maintenance of ECE applications shall have the

appropriate level of competence for the tasks undertaken.

EN ISO 15257 constitutes a suitable method of assessing Competence of Cathodic Protection Persons

which can be utilized for ECE as well as cathodic protection. Competence of Persons to the appropriate

level in the application sector of reinforced concrete for tasks undertaken should be demonstrated by

certification in accordance with EN ISO 15257 and suitable experience with ECE or by another

equivalent prequalification procedure.
6 Assessment and repair of the structure
6.1 General

Prior to undertaking chloride extraction, an assessment of the structure, including its physical

condition, its structural integrity and the nature and extent of any repairs which might be needed, shall

be performed in accordance with EN 1504-9. In most cases such condition surveys are made on the

occasion of damage observations and have resulted in the choice of ECE as a possible repair option. So

many of the following mentioned data might be available already, and just the missing and/ or out-of-

date information needs to be added as appropriate.
The investigations specified in 6.2 to 6.9 shall be carried out in order to:
a) determine the suitability of the structure for chloride extraction;
b) provide information for design and time of treatment;
c) identify any conditions which can preclude the use of chloride extraction.
6.2 Review of records

All available drawings, specifications, records and notes shall be reviewed for information on the

location, quantity, nature (e.g. mild or high strength steel, smooth or deformed bar, galvanized, epoxy-

coated) and continuity of the reinforcement, as well as the constituents and quality of the concrete.

The possible sensitivity to reduction of bond strength should be evaluated in the case of smooth

reinforcement.
6.3 Inspection

An inspection shall be carried out to ascertain the type, causes and extent of defects and any features of

the structure or of its surrounding environment, which could influence the application and effectiveness

of the chloride extraction. All areas of the structure, which require chloride extraction, shall be checked

for delamination of the concrete cover. Defects such as delamination, cracks, honeycombing or poor

construction joints which could permit significant water penetration, or prevent current flow and

thereby impair the effectiveness of the chloride extraction treatment, shall be recorded.

In areas, which have been previously repaired, the repair methods and materials used should be

identified as far as possible. If the concrete behind the repair is to be treated with chloride extraction,

the electrical resistivity and porosity of the repair media should be considered in comparison to the

original concrete.

The cause of any deterioration which is not attributable to corroding reinforcement shall be

determined.
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SIST EN 14038-2:2020
EN 14038-2:2020 (E)

If any signs of structural distress are evident, an assessment of both the load-bearing capacity of the

structure and the need for temporary or permanent strengthening or support should be made.

6.4 Assessment of corrosion activity

Corrosion measurements provide essential information about the effect of chloride on the corrosion

behaviour of the reinforcement and help to identify the concrete areas which are in need of appropriate

repair. Suitable measurement methods are potential survey, galvanostatic pulse measurements, AC

impedance measurements, linear polarization measurements (LPR) and Tafel polarization

measurements. Details and work principles of these methods as well as approaches for the

interpretation of the received data are discussed comprehensively in [3].

NOTE 1 A usual approach is to do a full-scale potential survey along with the inspection for concrete defects

first, to correlate these data with reinforcement cover depths and to assess corrosion suspect areas for a local

detailed inspection.

NOTE 2 Great care needs to be taken on the interpretation of the potential readings, as they are not only

influenced by macro-cell induced corrosion, but also by variations in concrete moisture, the total water content

and varying cover depths or concrete composition.

Better accuracy in the interpretation of the corrosion status can be obtained by including enhanced

methods (galvanostatic pulse, etc.) in the scope of survey. These methods can also prove the result and

success of the chloride extraction application; if this is intended initial data need to be taken on

specified test coordinates before the chloride extraction, preferably along with chloride profiles. If

available, these enhanced corrosion measurements should be applied.
6.5 Determination of chloride content

The chloride content of the concrete shall be determined as a proportion of the mass of cement or

concrete according to EN 14629 as well as the source of the chloride contamination. Concrete samples

shall be taken from areas expected to have the highest possible chloride content in order to ascertain

whether chloride contamination is present and the profile from the surface through the cover to behind

the reinforcement.

It shall be made certain by an appropriate condition survey that sufficient and correct information are

known about the chloride distribution across the concrete surface and the related depth of ingress. A

dust sampling plan shall be specified to monitor the chloride extraction progress in relation to the

initial condition. Chloride profiles shall be measured in all concrete areas with increased corrosion

activity.

The concrete samples taken for chloride analysis should also be analysed for their water content. This

provides additional information for an improved understanding of potential data (e.g. the reason for

negative potential readings) or for designing the chloride extraction application.

6.6 Visual inspection of the rebar surface and carbonation depth measurement

A visual inspection of the rebar surface shall be made in locations with high corrosion activity and/ or

high chloride content in rebar vicinity. The results shall be documented accordingly. Carbonation depth

shall be measured at several of those locations to ascertain its distribution according to EN 14630 and

to verify, if there is a possible combined limitation of the corrosion protection (especially at low

concrete cover). In such case, the chloride extraction treatment can be designed to meet the

requirements of EN 14038-1 as well.
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SIST EN 14038-2:2020
EN 14038-2:2020 (E)
6.7 Concrete cover thickness and reinforcement location measurements

Concrete cover thickness and reinforcement location measurements shall be carried out in order to

enable a determination to be made of comparative current flow through areas of thick and thin cover,

and to identify regions of varying reinforcement density. Any features that could impair the

effectiveness of chloride extraction, such as shielding of the reinforcement caused by embedded metal

mesh, metal fibres, metal plates, plastic sheets or non-conductive repair materials shall be identified.

Points at which short circuits between the reinforcing steel and the anodes could occur shall be noted.

6.8 Alkali aggregate reaction

If the concrete of the structure which is to be treated with chloride extraction contains aggregates

which can be sensitive to alkali, the risk of provoking an alkali aggregate reaction (AAR) shall be

considered prior to any treatment.

NOTE 1 No case of induced AAR has been reported in connection with chloride extraction.

NOTE 2 The use of lithium borate based electrolytes has been used on structures treated with ECE and

suffering from AAR (see SHRP field trial report [5]).
6.9 Reinforcement continuity and size

The reinforcement continuity shall be proven on site by measuring the electrical resistance between

reinforcing bars in mutually remote locations across the structure and between all reinforcing bars

exposed during concrete repairs (s
...

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