BS EN 480-14-2006 Admixtures for concrete mortar and grout - Test methods - Determination of the effect on corrosion susceptibility of reinforcing steel by potentiostatic electro-c.pdf

1、 g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58Test methods Part 14: Determination of the effect on corrosion susceptibility of reinforcing steel

2、by potentiostatic electro-chemical testThe European Standard EN 480-14:2006 has the status of a British StandardICS 91.100.30Admixtures for concrete, mortar and grout BRITISH STANDARDBS EN 480-14:2006BS EN 480-14:2006This British Standard was published under the authority of the Standards Policy and

3、 Strategy Committee on 30 November 2006 BSI 2006ISBN 0 580 49498 5Amendments issued since publicationAmd. No. Date Commentscontract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations. National forewordThis British Stand

4、ard was published by BSI. It is the UK implementation of EN 480-14:2006.The UK participation in its preparation was entrusted by Technical Committee B/517, Concrete, to Subcommittee B/517/3, Admixtures.A list of organizations represented on B/517/3 can be obtained on request to its secretary.This pu

5、blication does not purport to include all the necessary provisions of a EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 480-14October 2006ICS 91.100.30English VersionAdmixtures for concrete, mortar and grout - Test methods - Part14: Determination of the effect on corrosion susceptibility ofreinfor

6、cing steel by potentiostatic electro-chemical testAdjuvants pour bton, mortier et coulis - Mthodes dessai -Partie 14 : Dtermination de leffet sur la tendance lacorrosion de lacier pour armature au moyen dun essailectrochimique potentiostatiqueZusatzmittel fr Beton, Mrtel und Einpressmrtel -Prfverfah

7、ren - Teil 14: Bestimmung desKorrosionsverhaltens von Stahl in Beton -Elektrochemische Prfung bei gleich bleibendem PotentialThis European Standard was approved by CEN on 19 August 2006.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for givin

8、g this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions

9、(English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus,

10、Czech Republic, Denmark, Estonia, Finland, France,Germany, 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 STANDARDIZATIONCOMIT EURO

11、PEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2006 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 480-14:2006: EEN 480-14:2006 (E) 2 Contents Page Foreword3 1 Scope 4 2 Norm

12、ative references 4 3 Test principle4 4 Equipment, materials and test specimens5 4.1 Equipment and materials 5 4.1.1 Electrodes.5 4.1.2 Reference mortar .5 4.1.3 Moulds 5 4.1.4 Test cell solution5 4.1.5 Polarisation circuit.5 4.2 Preparation of test specimens .6 4.2.1 General6 4.2.2 Preparation of th

13、e working electrode 6 4.2.3 Preparation of the mortar specimens6 5 Testing 6 5.1 Preparation for testing 6 5.2 Test procedure.7 5.3 Test result.7 6 Test report 7 Bibliography 10 EN 480-14:2006 (E) 3 Foreword This document (EN 480-14:2006) has been prepared by Technical Committee CEN/TC 104 “Concrete

14、 and related products”, the secretariat of which is held by DIN. 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 2007, and conflicting national standards shall be withdrawn at the latest by

15、April 2007. This document has been prepared by Subcommittee 3 (SC 3) of TC 104 “Admixtures of concrete.” This document is part of the series EN 480 “Admixtures for concrete, mortar and grout - Test methods“ which include the following: Part 1: Reference concrete and reference mortar for testing Part

16、 2: Determination of setting time Part 4: Determination of bleeding of concrete Part 5: Determination of capillary absorption Part 6: Infrared analysis Part 8: Determination of the conventional dry material content Part 10: Determination of water soluble chloride content Part 11: Determination of ai

17、r void characteristics in hardened concrete Part 12: Determination of the alkali content of admixtures Part 13: Reference masonry mortar for testing mortar admixtures Part 14: Determination of the effect on corrosion susceptibility of reinforcing steel by potentiostatic electro-chemical test This do

18、cument is applicable together with the standards of the series EN 934 “Admixtures for concrete, mortar and grout. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus

19、, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EN 480-14:2006 (E) 4 1 Scope This European

20、Standard defines: A test method for determining the influence of an admixture on the corrosion of a steel bar embedded in a mortar sample held at an increased potential in an electrochemical cell. The method can be used to determine the harmlessness of admixtures with regard to corrosion of reinforc

21、ing but not stressed steel. It applies to all admixtures for concrete, mortar and grout in contact with reinforcing steel. NOTE 1 This test method does not apply to assessing corrosion behaviour of admixtures when used with high tensile steel. NOTE 2 This test method does not assess the efficacy of

22、admixtures defined as corrosion inhibitors. NOTE 3 The quantity of chloride ion present in admixtures is covered by a separate requirement in the relevant parts of the EN 934 series. 2 Normative references The following referenced documents are indispensable for the application of this document. For

23、 dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 196-1, Methods of testing cement Part 1: Determination of strength EN 197-1, Cement Part 1: Composition, specifications and conformity crite

24、ria for common cements 3 Test principle During the test, a steel bar, embedded in a cement mortar containing the admixture, is maintained at a constant potential relative to a reference electrode. The potential chosen is close to the higher level of the passive state for steel in plain concrete. Any

25、 detrimental effect from the addition of the admixture will be immediately obvious as the passive state will change, leading to increased anodic dissolution rates and corrosion currents above those of the control. The test specimen containing the admixture, is compared with a control specimen withou

26、t admixture, to assess the effect that the admixture has on the corrosion process. EN 480-14:2006 (E) 5 4 Equipment, materials and test specimens 4.1 Equipment and materials 4.1.1 Electrodes 4.1.1.1 Working electrode: comprising a smooth bar, without visible scratches or corrosion, of low carbon mil

27、d steel (carbon less than 0,4 %, steel tensile strength 300 MPa), e.g. S235JRG1 to EN 10025-1 and 10025-2. The working electrode is cylindrical, (7 + 1) mm in diameter and the length in contact with mortar is 65 mm (see Figure 1). 4.1.1.2 Reference electrode: saturated calomel electrode, silver/silv

28、er chloride electrode or mercury/mercuric oxide electrode. 4.1.1.3 Counter electrode: platinum electrode or a thin sheet of stainless steel (e.g. EN 10088-1 type X2CrNi19-11) with a submerged length equal to the length of the working electrode in contact with the mortar. 4.1.2 Reference mortar The c

29、omposition of the reference mortar shall conform to EN 196-1. The cement shall be a CEM I in accordance with EN 197-1 and C3A content 3,0 %; water shall be de-ionized and the water/cement ratio shall be 0,50. Preparation of the mortar shall be in accordance with EN 196-1. For each test, two mixes ar

30、e prepared: a reference control mortar, without admixture, and a reference test mortar which contains the admixture or admixture constituent being tested at the maximum recommended dose. All mortar is made using materials from the same delivery. If a liquid admixture is being tested, it is added to

31、the mixing water of the test mortar and the amount of mixing water is decreased by the water content of the admixture. If a powder/granulated admixture is being tested it is added to the sand for the test mortar. NOTE In some cases it may be difficult to obtain a dense, uniform and fully compacted m

32、ortar specimen when using the admixture at its maximum recommended dose under the specified test conditions. Segregation, excessive retardation, air entrainment or poor compaction due to early stiffening all have to be avoided as they may affect the test result. In such cases, modifications to the m

33、ixing and test procedures such as test and/or curing temperature or time/method of filling the mould should be agreed with the manufacturer and recorded in the test report. In exceptional cases, when testing retarding admixtures it may be necessary to increase the mix and curing temperature. When te

34、sting set accelerating admixtures for sprayed concrete use a w/c = 0,55, cool the constituents to (5 1) C and add the admixture 15 s before the end of mixing. 4.1.3 Moulds Moulds used in the preparation of a particular set of specimens (control and test) shall be made from cardboard, plastic or stee

35、l and essentially identical in internal dimensions. A suitable arrangement, including the dimensional requirement, is shown in Figure 1. 4.1.4 Test cell solution The electrolyte of the cell shall be a saturated calcium hydroxide solution at a temperature of (20 + 2) C. The electrolyte shall be made

36、from analytical grade calcium hydroxide in de-ionised water. 4.1.5 Polarisation circuit The polarisation circuit includes: potentiostat to apply a potential between the working electrode and the reference electrode, maintained at (+ 500 5) mVNHE. The potentiostat provides a constant voltage between

37、the working electrode and the EN 480-14:2006 (E) 6 counter electrode relative to the reference electrode. The potentiostat should have a minimum impedance of 100 M. ammeter, with an accuracy 0,1 A, to measure changes in the current between the working electrode and the counter electrode. The range o

38、f the ammeter should be between 0 A and x A where x = 100 times exposed surface of the working electrode in cm. 4.2 Preparation of test specimens 4.2.1 General Condition all the materials at (20 + 2) C before preparing the specimens. NOTE Following the note in 4.1.2 a different conditioning temperat

39、ure may be necessary when some admixtures are tested at their maximum recommended dose. 4.2.2 Preparation of the working electrode All steel bar working electrodes used in a particular set of tests shall be from the same heat. Before making the reinforced mortar specimen, clean the working electrode

40、 using metallographic emery paper, grade 400 and then degrease with acetone or other suitable solvent. Handle the bars (working electrodes) with gloved hands only from this point in the procedure. Immediately after cleaning, coat each working electrode with an appropriate epoxy resin for a length of

41、 approximately 40 mm centred about the point where it emerges from the mortar (see Figure 1). Measure the length and diameter of the uncoated part of the electrode to be encased in mortar to the nearest 1,0 mm and 0,1 mm respectively. NOTE 1 If the working electrode is not incorporated in mortar imm

42、ediately after cleaning and coating, store it in a desiccator at a relative humidity 30 %. If the surface has become tarnished it should be cleaned again before use. NOTE 2 Other coatings can be used in place of epoxy resin if they can be shown to give equivalent results. 4.2.3 Preparation of the mo

43、rtar specimens Prepare three similar specimens from each mortar mix. Place the working electrode centrally in the mould so that the mortar cover to the embedded part without coating is (20 5) mm and secure it to prevent movement during filling, compaction and whilst the mortar remains in the plastic

44、 state. Fill the moulds and compact to ensure complete compaction without segregation. If the mortar is not fully compacted or is subject to segregation, this can induce corrosion and invalidate the test. In such cases the test shall be repeated, if necessary with a change to the test conditions as

45、suggested in the note in 4.1.2. NOTE The working electrode may be placed in the mould after filling, provided it can be centrally located and full contact between the mortar and the bar achieved. After preparation store the specimens at (20 2)C and 95 % RH for 24 h prior to demoulding. If the specim

46、ens do not harden in 24 h, demould after hardening and record the age for inclusion in the test report. 5 Testing 5.1 Preparation for testing After demoulding place the specimen vertically into a test cell, fill with the test cell solution (clause 4.1.4), to within 10 mm of the top of the mortar cyl

47、inder, and leave for 24 h at (20 2) C. Do not allow water or the test cell solution to come into contact with the top surface of the specimen at any time as moisture around the embedded bar may lead to errors in the test. EN 480-14:2006 (E) 7 5.2 Test procedure After the 24 h equilibration period, t

48、horoughly clean the exposed end of the working electrode then connect the working electrode, reference electrode and the counter electrode to the polarisation circuit as shown in Figure 2. Raise the output of the potentiostat, until the working electrode potential, referred to the normal hydrogen re

49、ference electrode, reaches (+500 5) mVNHE.Maintain this potential for at least 24 h whilst continuously recording the current between the working electrode and the counter electrode. Keep the top of the test specimen dry as contact with water or the test cell solution can lead to errors in the test result. After completing the 24 h test period, break open the test specimens and examine the working electrodes for crevice corrosion at the boundary of the protective coating. If evidence of