1、raising standards worldwide NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW BSI Standards Publication PD CEN/TR 16142:2011 Concrete A study of the characteristic leaching behaviour of hardened concrete for use in the natural environmentPD CEN/TR 16142:2011 PUBLISHED DOCUMENT N
2、ational foreword This Published Document is the UK implementation of CEN/TR 16142:2011. The UK participation in its preparation was entrusted to Technical Committee B/516/12, Sampling and testing. A list of organizations represented on this committee can be obtained on request to its secretary. This
3、 publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. BSI 2011 ISBN 978 0 580 71784 0 ICS 91.100.10; 91.100.30 Compliance with a British Standard cannot confer immunity from legal obligations. This Published Document w
4、as published under the authority of the Standards Policy and Strategy Committee on 31 March 2011. Amendments issued since publication Date 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
5、 - A study of the characteristic 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 20
6、10. It has been drawn up by 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, Net
7、herlands, Norway, Poland, 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 exploitatio
8、n in any form and by any means reserved worldwide for CEN national Members. Ref. No. CEN/TR 16142:2011: EPD CEN/TR 16142:2011 CEN/TR 16142:2011 (E) 2 Contents Page Foreword 4 Summary 5 1 Introduction 6 Part I . 8 2 Scope of the study . 8 2.1 Summary of three interlaboratory studies (ILS) . 8 2.1.1 F
9、irst interlaboratory study and its evaluation (ILS #1) 8 2.1.2 Second interlaboratory study and its evaluation (ILS #2) . 13 2.1.3 Third interlaboratory study and its evaluation (ILS #3) . 17 3 The experimental precision and its implications . 20 3.1 Introduction 20 3.2 Discussion of the precision e
10、stimates . . 22 4 Standardisation of the characterisation leaching method 23 4.1 Introduction 23 4.2 Potential applications for the method . 23 4.3 Necessary developments before any method can be applied 24 5 Conclusions . 24 6 Appendices . 26 6.1 Members of the Project Team that undertook the inves
11、tigations 26 6.2 Laboratories participating in the precision experiment in ILS #3 26 7 References 27 Part II (informative) TEST METHOD USED IN THE STUDY FOR CHARACTERISATION OF LEACHING 28 1 Scope 28 2 Normative references 29 3 Terms, definitions, symbols and abbreviations . 29 4 Materials and reage
12、nts 31 4.1 Materials . 31 4.1.1 General 31 4.1.2 Requirements for standard specimens as test pieces (P D ) and test pieces (P A ) 31 4.1.3 Requirements for precast products (or parts thereof) as test pieces (P D ) and (P A ) . 33 4.2 Reagents . 33 4.2.1 General requirements 33 4.2.2 Leachant . 33 4.
13、2.3 Acids . 33 4.2.4 Oxidising agent . . 34 5 Apparatus . 34 5.1 General 34 5.2 Sealable tank (or bucket) . . 35 5.3 Filtering equipment 35 5.4 Membrane filters 35 5.5 Plastics bottles . 35 5.6 pH meter . 36 5.7 Conductivity meter 36 6 Determining the leaching behaviour. . 36 6.1 General 36 PD CEN/T
14、R 16142:2011 CEN/TR 16142:2011 (E) 3 6.2 Principles . 36 6.2.1 Diffusion (tank) test . 36 6.2.2 Availability test 36 6.2.3 Surface area determination 36 6.2.4 Assessment of the characteristic leaching 36 6.3 Diffusion (tank) test . 37 6.3.1 Test conditions 37 6.3.2 Procedure . 37 7 Calculation of cu
15、mulative leaching and expression of results 38 7.1 Measured leaching of a component per leachate fraction 38 7.2 Measured and theoretical cumulative leaching of a component . 39 7.2.1 General . 39 7.2.2 Measured cumulative leaching of a component 39 7.2.3 Theoretical cumulative leaching of a compone
16、nt 40 8 Precision of cumulative leaching 40 8.1 General . 40 8.2 Precision of the availability test . 41 8.3 Precision of the diffusion (tank) test . 42 9 Characterising the leaching behaviour . 42 9.1 General . 42 9.2 Determining the controlling leaching mechanism . 43 9.3 Calculating the effective
17、 and mean effective diffusion coefficients of a component 43 9.3.1 Effective diffusion coefficient of a component 43 9.3.2 Mean effective diffusion coefficient of a component 44 9.3.3 Selection of the lowest value of the mean effective diffusion coefficient . 44 9.4 Calculating the cumulative leachi
18、ng of a component per surface unit, per time interval . 44 9.5 Assessment of components for which no diffusion coefficient can be determined . 45 9.6 Assessment of a diffusion coefficient . 45 9.6.1 General . 45 9.6.2 Assessment of the negative logarithm of the mean effective diffusion coefficient .
19、 45 9.7 Comparison of the mobility of a component with the free mobility of the same component in water . 45 9.7.1 General . 45 9.7.2 Calculating the tortuosity . 46 9.7.3 Calculating the retention factor . 46 9.8 Calculating the quantity leached, per mass unit, in the diffusion (tank) test . 46 9.9
20、 Calculating the extent of depletion of a component 47 10 Test report 47 Annex A (normative) Determination of the available (potential) amount of a component for leaching 49 A.1 Procedure . 49 A.2 Expression of results 49 Annex B (normative) Determination of the surface area (A) of a test piece (PD)
21、 for use in the diffusion (tank) test . 50 B.1 Procedure . 50 B.2 Calculation and expression of results 50 Annex C (informative) Diagrammatic representation of the diffusion (tank) leaching procedure . 51 Annex D (informative) Supplementary procedures for calculating the indicative upper limit for l
22、eaching for particular characteristics of the leaching behaviour . 52 D.1 General . 52 D.2 Diffusion-controlled leaching of components for which no diffusion coefficient can be established . 52 Bibliography 55 PD CEN/TR 16142:2011 CEN/TR 16142:2011 (E) 4 Foreword This document (CEN/TR 16142:2011) ha
23、s 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 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 15
24、678:2008 which is complementary to this TR. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. PD CEN/TR 16142:2011 CEN/TR 16142:2011 (E)
25、 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/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 establishi
26、ng the effects, if any, of concrete on the natural environment and the potential effects of cementitious materials on the quality of drinking water. This Technical Report deals only with developments, as officially reported, by a consortium of Dutch/German Institutes, to the European Commission in E
27、UR 17869 EN 1, leading to a performance test method for characterising the leaching behaviour of hardened concrete for use in contact with the natural environment. NOTE The standardisation of test methods for the use of cementitious materials (possibly including concrete) in contact with drinking wa
28、ter, although not fundamentally different in principle, is being developed within an adhoc group of CEN/TC 164/WG 3 and will be reported elsewhere. The protection of the natural environment and the publics health and safety are matters of major importance. Also of significant importance, however, is
29、 the efficient and sustainable use of natural and secondary materials/resources. Many of these may be used as constituents of concrete. The need to appropriately balance these two issues within the concept of sustainable construction, provided the motivation for the investigations considered in this
30、 Technical Report. The prenormative research, underpinning this Technical Report, included a literature survey and three progressively staged interlaboratory studies (ILS). These led to the refinement of a characterisation (sequential leaching) test, comprising a tank (diffusion) test and a separate
31、 availability (maximum leaching) test. A single-extraction compliance test was not developed. A range of inorganic components/species (anionic and cationic) was targeted; some with a potential environmental significance, others of a more mechanistic relevance. Overall, a statistical and mechanistic
32、evaluation of the results within EUR 17869 EN 1 and an environmental analysis undertaken in this Technical Report, has lead to the following conclusions. The leaching of major components/species, which have no environmental significance (e.g. Ca, Na, K and SO 4 ) from monolithic hardened concrete is
33、 diffusion controlled. Diffusion control could not be demonstrated, even after 14 days of leaching, for most environmentally relevant elements (e.g. 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 sensiti
34、ve instrumental techniques employed. Leached levels of components from monoliths are not related, in any simple or consistent manner, to the total concentrations of components present in concrete, and are, typically, orders of magnitude smaller. Leached levels of components from monolithic specimens
35、 are not related, in any simple or consistent manner, to amounts apparently available for leaching as indicated from a leaching test on finely ground concrete and the appropriateness of using such a test in attempting to characterise the leaching behaviour of hardened concrete is subject to continui
36、ng discussion. The concentration levels found in almost all leachates from the different tests were very low and often near the limit of the chemical analysis, indicating the good environmental quality of the concrete mixes tested. PD CEN/TR 16142:2011 CEN/TR 16142:2011 (E) 6 Concrete, containing a
37、bituminous coal fly ash constituent specifically selected for its relatively high content of trace/heavy metals, and designed to represent a worst case within EN 206-1 2 in terms of permeability, did not show significant leaching of trace/heavy metals. Most components were at concentrations below th
38、e analytical limits of detection. The anomalous leaching behaviour shown by specimens where the mixing water was spiked with aqueous solutions of the very mobile oxyanions of As, Cr, Cd and V, indicates that they were not representative of real concretes, as acknowledged by the research investigator
39、s. The disproportionate effect observed in the investigations, between the relatively large amounts of trace/heavy metals added as spikes to fresh concrete and apparently available for leaching, versus the minimal amounts actually leached, suggests that substituting standardized recycled or more mar
40、ginal, but standardized, novel materials for the traditional constituents of concrete, would not significantly affect concretes environmental compatibility. Subjecting the solid constituents of concrete to test, in isolation, either on the basis of their total elemental composition, or their respons
41、e to an availability test, or their individual performance in a compliance test, will give no indication of their potential performance (either relative or absolute) when chemically and physically bound in hardened concrete. The characterisation leaching method, reproduced in Part II of this Technic
42、al Report, demonstrates such poor reproducibility (R approximately 76 % at 14d for trace metals As/Cd/Cr/V) that without much further investigation and 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. Concre
43、tes within the envelope of compositions permitted in the EN 206-1 2 will have an insignificant impact upon the natural environment under conditions of natural exposure. 1 Introduction Traditionally, hardened concrete has not been perceived to be a material which has contributed emissions adversely a
44、ffecting the quality of the natural environment. Indeed, concrete construction in contact with the natural environment constitutes the bedrock of infrastructure and the built environment. Additionally, hardened concrete has never been shown to be responsible for any incidence of environmental pollut
45、ion. Accordingly, within the range of traditional compositions used in the EU Member States, concretes environmental service record can be taken to be unblemished. Concrete, unlike most other construction materials, is an active material; its chemical and physical microstructure develops in a contin
46、uous process as it ages. These changes give rise to a densification of the matrix, with attendant reductions in porosity/permeability and a more efficient/effective binding of chemical species within the hydrate structures. It would be expected that concretes leaching behaviour would also be subject
47、 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 question whether protocols, derived as in this study, from those developed for testing inert materials, are at all appropriate for concrete. Concrete is,
48、 however, in common with other construction materials, subject to continual product development. Its compositional complexity is increasing, as constituent 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 potential emission levels. In addition, envi
