BS DD CEN TS 14038-2-2011 Electrochemical re-alkalization and chloride extraction treatments for reinforced concrete Chloride extraction《加筋混凝土的电化学再碱化和氯化物萃取处理 氯化物萃取》.pdf

1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationDD CEN/TS 14038-2:2011Electrochemical re-alkalizationand chloride extractiontreatments for rein-forcedconcretePart 2: Chloride extractionDD CEN/TS 14038-2:2011 DRAFT FOR DEVELOPM

2、ENTNational forewordThis Draft for Development is the UK implementation of CEN/TS14038-2:2011.This publication is not to be regarded as a British Standard.It is being issued in the Draft for Development series of publicationsand is of a provisional nature. It should be applied on thisprovisional bas

3、is, so that information and experience of its practicalapplication can be obtained.Comments arising from the use of this Draft for Developmentare requested so that UK experience can be reported to theinternational organization responsible for its conversion toan international standard. A review of t

4、his publication willbe initiated not later than 3 years after its publication by theinternational organization so that a decision can be taken on itsstatus. Notification of the start of the review period will be made inan announcement in the appropriate issue of Update Standards.According to the rep

5、lies received by the end of the review period,the responsible BSI Committee will decide whether to support theconversion into an international Standard, to extend the life of theTechnical Specification or to withdraw it. Comments should be sentto the Secretary of the responsible BSI Technical Commit

6、tee at BritishStandards House, 389 Chiswick High Road, London W4 4AL.The UK participation in its preparation was entrusted to TechnicalCommittee GEL/603, Cathodic protection.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not pur

7、port to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. BSI 2011ISBN 978 0 580 63862 6ICS 91.080.40; 91.100.30Compliance with a British Standard cannot confer immunity fromlegal obligations.This Draft for Development was published under the author

8、ity ofthe Standards Policy and Strategy Committee on 28 February 2011.Amendments issued since publicationDate Text affectedDD CEN/TS 14038-2:2011TECHNICAL SPECIFICATION SPCIFICATION TECHNIQUE TECHNISCHE SPEZIFIKATION CEN/TS 14038-2 February 2011 ICS 91.100.30 English Version Electrochemical re-alkal

9、ization and chloride extraction treatments for rein-forced concrete - Part 2: Chloride extractionTraitements lectrochimiques de ralcalinisation et dextraction de chlorures applicables au bton arm - Partie 2: Extraction de chlorures Elektrochemische Realkalisierung und Chloridextraktionsbehandlungen

10、fr Stahlbeton - Teil 2: Chloridextraktion This Technical Specification (CEN/TS) was approved by CEN on 15 May 2010 for provisional application. The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to submit their comments, pa

11、rticularly on the question whether the CEN/TS can be converted into a European Standard. CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS available promptly at national level in an appropriate form. It is permissible to keep confli

12、cting national standards in force (in parallel to the CEN/TS) until the final decision about the possible conversion of the CEN/TS into an EN is reached. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, G

13、ermany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORM

14、UNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2011 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. CEN/TS 14038-2:2011: EDD CEN/TS 14038-2:2011CEN/TS 14038-2:2011 (E) 2 Contents Page Foreword 3Introduction .41 Scope 52 Norm

15、ative references 53 Terms and definitions .54 Principle 65 Assessment and repair of the structure 65.1 General 65.2 Review of records 65.3 Inspection .65.4 Determination of chloride content .75.5 Carbonation depth measurement 75.6 Concrete cover thickness and reinforcement location measurements .75.

16、7 Alkali aggregate reaction 75.8 Reinforcement continuity and size 75.9 Repair 85.9.1 General 85.9.2 Concrete removal.85.9.3 Reinforcement preparation .86 Materials and equipment .86.1 Calibration of instrumentation .86.2 Anode system 86.2.1 General 86.2.2 Anode 86.2.3 Anode zone .86.2.4 Alkaline el

17、ectrolyte solution .96.3 Electric cables 96.4 Power supply 97 Installation procedures .97.1 Electrical continuity .97.2 Other metallic parts within the treatment area .97.3 Performance monitoring 107.4 Installation of anode system . 107.5 Protection of electrolyte solution 107.6 Electrical installat

18、ion 107.7 Preliminary testing and documentation . 108 Commissioning, operation and termination of treatment 118.1 Visual inspection 118.2 Safety precautions 118.3 Energising and adjustment of current output . 118.4 Routine inspection and maintenance . 118.5 Chloride extraction process monitoring 118

19、.6 Termination of treatment . 129 Final report 1210 Post-treatment coating and monitoring . 13Bibliography . 14 DD CEN/TS 14038-2:2011CEN/TS 14038-2:2011 (E) 3 Foreword This document (CEN/TS 14038-2:2011) has been prepared by Technical Committee CEN/TC 219 “Cathodic protection”, the secretariat of w

20、hich is held by BSI. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. According to the CEN/CENELEC Internal Regulations, the national s

21、tandards organizations of the following countries are bound to announce this Technical Specification: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Lat-via, Lithuania, Luxembourg, Malta, Netherlands,

22、 Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. DD CEN/TS 14038-2:2011CEN/TS 14038-2:2011 (E) 4 Introduction The purpose of chloride extraction is to rehabilitate a reinforced concrete part from corrosion activity and to provide long term co

23、rrosion protection of steel reinforcement in concrete which has been affected by chloride and to re-establish self protection ability. The duration of treatment is from several weeks up to as much as several months, depending on the amount of accumulated chloride, the permeability of the concrete, t

24、he lay-out of the reinforcement and other factors. The decision to terminate the application should be made accord-ing to the specific requirements detailed in this technical specification. There are other electrochemical procedures that can be used to provide corrosion protection of steel in con-cr

25、ete structures. These include cathodic protection and re-alkalisation. There is a European standard for ca-thodic protection of steel in concrete (EN 12696) and a European Technical Specification for the re-alkalisation of carbonated concrete (TS 14038-1). It has been assumed in the drafting of this

26、 Technical Specification that the execution of its provisions will be entrusted to appropriately qualified and competent people, for whose use it has been prepared. DD CEN/TS 14038-2:2011CEN/TS 14038-2:2011 (E) 5 1 Scope This Technical Specification specifies a procedure for carrying out impressed c

27、urrent 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 t

28、here is no risk of hydrogen embrittlement, if necessary by conduct-ing trials and installing monitoring during the treatment. This Technical Specification does not apply to pretensioned concrete, which may suffer hydrogen embrittle-ment on the stressing bars during chloride extraction, or to concret

29、e containing epoxy-coated or galvanised reinforcement. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated refer-ences, only the edition cited applies. For undated references, the latest edition of the referenced document (inclu

30、ding any amendments) applies. EN 1504-2:2004, Products and systems for the protection and repair of concrete structures: Definitions, re-quirements, quality control and evaluation of conformity - Part 2: Surface protection systems for concrete EN 1504-9, Products and systems for the protection and r

31、epair of concrete structures - Definitions, require-ments, quality control and evaluation of conformity - Part 9: General principles for the use of products and sys-tems EN 12696, Cathodic protection of steel in concrete EN 14629, Products and systems for the protection and repair of concrete struct

32、ures - Test methods - Deter-mination of chloride content in hardened concrete EN 14630, Products and systems for the protection and repair of concrete structures - Test methods - Deter-mination of carbonation depth in hardened concrete by the phenolphthalein method EN ISO 8044:1999, Corrosion of met

33、als and alloys Basic terms and definitions (ISO 8044:1999) 3 Terms and definitions For the purposes of this Technical Specification, the terms and definitions given in EN ISO 8044:1999 and EN 1504-2:2004 and the following apply. 3.1 chloride extraction electrochemical treatment for providing a low c

34、hloride content and developing a high pH value to concrete, which surrounds reinforcing bars, corresponding to sound, carbonated or non-carbonated concrete. DD CEN/TS 14038-2:2011CEN/TS 14038-2:2011 (E) 6 4 Principle Chloride extraction of reinforced concrete is performed by applying an electric fie

35、ld between the steel rein-forcement embedded in the concrete and an anode surrounded by an alkaline electrolyte solution containing hydroxyl ions temporarily placed on the concrete surface. Dissolved, negatively charged ions such as chlo-ride - will be moved from the reinforcement to the external el

36、ectrode. This is mainly a physical process. Coincidentally, the electrochemical reactions occurring at the steel surface provide the evolution of hydroxyl ions by the reduction of oxygen and water. This process alkalises the concrete in the vicinity of the rebar as described in CEN/TS 14038-1. NOTE

37、1 The chloride content cannot be reduced to zero; an usual target content is an average profile of 0.4 %, related to the cement mass. To achieve this, the driving voltage between reinforcement and external anode should be set as high as possible usually ranging between 30 V and 40 V. NOTE 2 The chlo

38、ride 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. Ev

39、en treatments from the opposite side of a concrete slab are possible, but require an extended time of application. NOTE 3 If the reinforcement surface is covered by corrosion products, these oxides have to be reduced prior to the possible reduction of oxygen and water. During this period, which may

40、consume theoretically up to 700 Ah/m, few if any hydroxyl ions can be developed. In such a case, hydrogen evolution is likely just as in the later stages of the chloride ex-traction treatment. NOTE 4 Details of the principle underlying this process are given in the European Federation of Corrosion r

41、eport 1. NOTE 5 Some electrolyte materials may change the surface appearance of the concrete. 5 Assessment and repair of the structure 5.1 General Prior to undertaking chloride extraction, an assessment of the structure, including its physical condition, its structural integrity and the nature and e

42、xtent of any repairs which might be needed, shall be performed in ac-cordance with EN1504-9. The investigations specified in 5.2 to 5.8 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. 5.

43、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, galvanised, epoxy-coated) and con-tinuity of the reinforcement, as well as the constituents and

44、 quality of the concrete. NOTE The possible sensitivity to reduction of bond strength should be evaluated in the case of smooth reinforce-ment. 5.3 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 surroundin

45、g environment, which could influence the application and effectiveness of chloride DD CEN/TS 14038-2:2011CEN/TS 14038-2:2011 (E) 7 extraction. All areas of the structure which require chloride extraction shall be checked for delamination of the concrete cover. Defects such as delaminations, cracks,

46、honeycombing or poor construction joints which could permit significant water penetration, or prevent current flow and thereby impair the effectiveness of the chlo-ride extraction treatment, shall be recorded. NOTE 1 In areas which have been previously repaired, the repair methods and materials shou

47、ld be identified, as far as possible. If the concrete behind the repair is to be treated with chloride extraction, the deviating electrical resistivity and porosity of the repair media should be considered. The cause of any deterioration which is not attributable to corroding reinforcement shall be

48、determined. NOTE 2 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. 5.4 Determination of chloride content The chloride content of the concrete shall be de

49、termined as a proportion of the mass of cement or concrete in accordance with EN 14629. Concrete samples shall be taken from areas expected to have the highest possi-ble chloride content in order to ascertain whether chloride contamination is present and the profile from the surface through the cover to behind the reinforcement. 5.5 Carbonation depth measurement Carbonation depth shall be measur