1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationPD CEN/TR 16142:2011Concrete A study ofthe characteristic leachingbehaviour of hardenedconcrete for use in the naturalenvironmentPD CEN/TR 16142:2011 PUBLISHED DOCUMENTNational f
2、orewordThis Published Document is the UK implementation of CEN/TR16142:2011.The UK participation in its preparation was entrusted to TechnicalCommittee B/516/12, Sampling and testing.A list of organizations represented on this committee can beobtained on request to its secretary.This publication doe
3、s not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. BSI 2011ISBN 978 0 580 71784 0ICS 91.100.10; 91.100.30Compliance with a British Standard cannot confer immunity fromlegal obligations.This Published Document was published under the
4、authority of theStandards Policy and Strategy Committee on 31 March 2011.Amendments issued since publicationDate Text affectedPD CEN/TR 16142:2011TECHNICAL REPORT RAPPORT TECHNIQUE TECHNISCHER BERICHT CEN/TR 16142 March 2011 ICS 91.100.30; 91.100.10 English Version Concrete - A study of the characte
5、ristic leaching behaviour of hardened concrete for use in the natural environment Zement - Eine Untersuchung der bezeichnenden Auslaugungseigenschaften von ausgehrtetem Beton zur Verwendung in natrlichen Umgebungen This Technical Report was approved by CEN on 20 December 2010. It has been drawn up b
6、y the Technical Committee CEN/TC 51. 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,
7、Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2011 CEN All rights of exploitation in any form and by any m
8、eans reserved worldwide for CEN national Members. Ref. No. CEN/TR 16142:2011: EPD CEN/TR 16142:2011CEN/TR 16142:2011 (E) 2 Contents Page Foreword 4Summary 51 Introduction 6Part I . 82 Scope of the study . 82.1 Summary of three interlaboratory studies (ILS) . 82.1.1 First interlaboratory study and it
9、s evaluation (ILS #1) 82.1.2 Second interlaboratory study and its evaluation (ILS #2) . 132.1.3 Third interlaboratory study and its evaluation (ILS #3) . 173 The experimental precision and its implications . 203.1 Introduction 203.2 Discussion of the precision estimates 224 Standardisation of the ch
10、aracterisation leaching method 234.1 Introduction 234.2 Potential applications for the method . 234.3 Necessary developments before any method can be applied 245 Conclusions . 246 Appendices . 266.1 Members of the Project Team that undertook the investigations 266.2 Laboratories participating in the
11、 precision experiment in ILS #3 267 References 27Part II (informative) TEST METHOD USED IN THE STUDY FOR CHARACTERISATION OF LEACHING 281 Scope 282 Normative references 293 Terms, definitions, symbols and abbreviations . 294 Materials and reagents 314.1 Materials . 314.1.1 General 314.1.2 Requiremen
12、ts for standard specimens as test pieces (PD) and test pieces (PA) 314.1.3 Requirements for precast products (or parts thereof) as test pieces (PD) and (PA) . 334.2 Reagents . 334.2.1 General requirements 334.2.2 Leachant . 334.2.3 Acids . 334.2.4 Oxidising agent 345 Apparatus . 345.1 General 345.2
13、Sealable tank (or bucket) 355.3 Filtering equipment 355.4 Membrane filters 355.5 Plastics bottles . 355.6 pH meter . 365.7 Conductivity meter 366 Determining the leaching behaviour 366.1 General 36PD CEN/TR 16142:2011CEN/TR 16142:2011 (E) 3 6.2 Principles . 366.2.1 Diffusion (tank) test . 366.2.2 Av
14、ailability test 366.2.3 Surface area determination 366.2.4 Assessment of the characteristic leaching 366.3 Diffusion (tank) test . 376.3.1 Test conditions 376.3.2 Procedure . 377 Calculation of cumulative leaching and expression of results 387.1 Measured leaching of a component per leachate fraction
15、 387.2 Measured and theoretical cumulative leaching of a component . 397.2.1 General . 397.2.2 Measured cumulative leaching of a component 397.2.3 Theoretical cumulative leaching of a component 408 Precision of cumulative leaching 408.1 General . 408.2 Precision of the availability test . 418.3 Prec
16、ision of the diffusion (tank) test . 429 Characterising the leaching behaviour . 429.1 General . 429.2 Determining the controlling leaching mechanism . 439.3 Calculating the effective and mean effective diffusion coefficients of a component 439.3.1 Effective diffusion coefficient of a component 439.
17、3.2 Mean effective diffusion coefficient of a component 449.3.3 Selection of the lowest value of the mean effective diffusion coefficient . 449.4 Calculating the cumulative leaching of a component per surface unit, per time interval . 449.5 Assessment of components for which no diffusion coefficient
18、 can be determined . 459.6 Assessment of a diffusion coefficient . 459.6.1 General . 459.6.2 Assessment of the negative logarithm of the mean effective diffusion coefficient . 459.7 Comparison of the mobility of a component with the free mobility of the same component in water . 459.7.1 General . 45
19、9.7.2 Calculating the tortuosity . 469.7.3 Calculating the retention factor . 469.8 Calculating the quantity leached, per mass unit, in the diffusion (tank) test . 469.9 Calculating the extent of depletion of a component 4710 Test report 47Annex A (normative) Determination of the available (potentia
20、l) amount of a component for leaching 49A.1 Procedure . 49A.2 Expression of results 49Annex B (normative) Determination of the surface area (A) of a test piece (PD) for use in the diffusion (tank) test . 50B.1 Procedure . 50B.2 Calculation and expression of results 50Annex C (informative) Diagrammat
21、ic representation of the diffusion (tank) leaching procedure . 51Annex D (informative) Supplementary procedures for calculating the indicative upper limit for leaching for particular characteristics of the leaching behaviour . 52D.1 General . 52D.2 Diffusion-controlled leaching of components for whi
22、ch no diffusion coefficient can be established . 52Bibliography 55PD CEN/TR 16142:2011CEN/TR 16142:2011 (E) 4 Foreword This document (CEN/TR 16142:2011) has been prepared by Technical Committee CEN/TC 51 “Cement and building limes”, the secretariat of which is held by NBN. The work which the report
23、refers to was developed by CEN/TC51-TC104 JWG12/TG6 in the period 1994-1999. JWG12/TG6 has continued to work on this subject and has produced the CEN/TR 15678:2008 which is complementary to this TR. Attention is drawn to the possibility that some of the elements of this document may be the subject o
24、f patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. PD CEN/TR 16142:2011CEN/TR 16142:2011 (E) 5 Summary At the initiative of CEN/TC 51 (Cement and building limes) and CEN/TC 104 (Concrete and related products), a task group (TG 6) of TC 51
25、/WG 12 was convened in order to accompany or follow research work being carried out within the EC research programme which has the objective of establishing the effects, if any, of concrete on the natural environment and the potential effects of cementitious materials on the quality of drinking wate
26、r. This Technical Report deals only with developments, as officially reported, by a consortium of Dutch/German Institutes, to the European Commission in EUR 17869 EN 1, leading to a performance test method for characterising the leaching behaviour of hardened concrete for use in contact with the nat
27、ural environment. NOTE The standardisation of test methods for the use of cementitious materials (possibly including concrete) in contact with drinking water, although not fundamentally different in principle, is being developed within an adhoc group of CEN/TC 164/WG 3 and will be reported elsewhere
28、. The protection of the natural environment and the publics health and safety are matters of major importance. Also of significant importance, however, is the efficient and sustainable use of natural and secondary materials/resources. Many of these may be used as constituents of concrete. The need t
29、o appropriately balance these two issues within the concept of sustainable construction, provided the motivation for the investigations considered in this Technical Report. The prenormative research, underpinning this Technical Report, included a literature survey and three progressively staged inte
30、rlaboratory studies (ILS). These led to the refinement of a characterisation (sequential leaching) test, comprising a tank (diffusion) test and a separate availability (maximum leaching) test. A single-extraction compliance test was not developed. A range of inorganic components/species (anionic and
31、 cationic) was targeted; some with a potential environmental significance, others of a more mechanistic relevance. Overall, a statistical and mechanistic evaluation of the results within EUR 17869 EN 1 and an environmental analysis undertaken in this Technical Report, has lead to the following concl
32、usions. The leaching of major components/species, which have no environmental significance (e.g. Ca, Na, K and SO4) from monolithic hardened concrete is diffusion controlled. Diffusion control could not be demonstrated, even after 14 days of leaching, for most environmentally relevant elements (e.g.
33、 As, Cd, Co and Cu) even from a relatively weak and porous concrete, since concentrations were at or below the limits of detections (DTL) of the sensitive instrumental techniques employed. Leached levels of components from monoliths are not related, in any simple or consistent manner, to the total c
34、oncentrations of components present in concrete, and are, typically, orders of magnitude smaller. Leached levels of components from monolithic specimens are not related, in any simple or consistent manner, to amounts apparently available for leaching as indicated from a leaching test on finely groun
35、d concrete and the appropriateness of using such a test in attempting to characterise the leaching behaviour of hardened concrete is subject to continuing discussion. The concentration levels found in almost all leachates from the different tests were very low and often near the limit of the chemica
36、l analysis, indicating the good environmental quality of the concrete mixes tested. PD CEN/TR 16142:2011CEN/TR 16142:2011 (E) 6 Concrete, containing a bituminous coal fly ash constituent specifically selected for its relatively high content of trace/heavy metals, and designed to represent a worst ca
37、se within EN 206-1 2 in terms of permeability, did not show significant leaching of trace/heavy metals. Most components were at concentrations below the analytical limits of detection. The anomalous leaching behaviour shown by specimens where the mixing water was spiked with aqueous solutions of the
38、 very mobile oxyanions of As, Cr, Cd and V, indicates that they were not representative of real concretes, as acknowledged by the research investigators. The disproportionate effect observed in the investigations, between the relatively large amounts of trace/heavy metals added as spikes to fresh co
39、ncrete and apparently available for leaching, versus the minimal amounts actually leached, suggests that substituting standardized recycled or more marginal, but standardized, novel materials for the traditional constituents of concrete, would not significantly affect concretes environmental compati
40、bility. Subjecting the solid constituents of concrete to test, in isolation, either on the basis of their total elemental composition, or their response to an availability test, or their individual performance in a compliance test, will give no indication of their potential performance (either relat
41、ive or absolute) when chemically and physically bound in hardened concrete. The characterisation leaching method, reproduced in Part II of this Technical Report, demonstrates such poor reproducibility (R approximately 76 % at 14d for trace metals As/Cd/Cr/V) that without much further investigation a
42、nd development, it should not proceed to CEN/TS status or become the precursor to a draft compliance test or be used for any regulatory purpose. Concretes within the envelope of compositions permitted in the EN 206-1 2 will have an insignificant impact upon the natural environment under conditions o
43、f natural exposure. 1 Introduction Traditionally, hardened concrete has not been perceived to be a material which has contributed emissions adversely affecting the quality of the natural environment. Indeed, concrete construction in contact with the natural environment constitutes the bedrock of inf
44、rastructure and the built environment. Additionally, hardened concrete has never been shown to be responsible for any incidence of environmental pollution. Accordingly, within the range of traditional compositions used in the EU Member States, concretes environmental service record can be taken to b
45、e unblemished. Concrete, unlike most other construction materials, is an active material; its chemical and physical microstructure develops in a continuous process as it ages. These changes give rise to a densification of the matrix, with attendant reductions in porosity/permeability and a more effi
46、cient/effective binding of chemical species within the hydrate structures. It would be expected that concretes leaching behaviour would also be subject to age-related changes and that this would be dissimilar to many other materials. Much research indicates that this is the case and so calls into qu
47、estion whether protocols, derived as in this study, from those developed for testing inert materials, are at all appropriate for concrete. Concrete is, however, in common with other construction materials, subject to continual product development. Its compositional complexity is increasing, as const
48、ituent materials, formerly considered to be marginal, are either now in use or being considered for use. In the absence of quantitative information, some of the more marginal materials (e.g. where a total analysis reveals an apparently high heavy metal content) can give rise to concerns about their
49、potential emission levels. In addition, environmental regulatory activity, although at different points in the cycle in different EU Member States, is more and more subject to centralised direction via instruments such as EU Directives and mandates, and is generally increasing in its pace and scope. PD CEN/TR 16142:2011CEN/TR 16142:2011 (E) 7 Within this operational framework, standar
