SIST-TP CEN/TR 16142:2011
(Main)Concrete - A study of the characteristic leaching behaviour of hardened concrete for use in the natural environment
Concrete - A study of the characteristic leaching behaviour of hardened concrete for use in the natural environment
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 establishing the effects, if any, of concrete on the natural environment and the potential effects of cementitious materials on the quality of drinking water.
This 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 natural environment.
Zement - Studie zum charakteristischen Auslaugverhalten von Festbetonen zur Verwendung in der natürlichen Umwelt
Auf Initiative von CEN/TC 51 (Zement und Baukalk) und CEN/TC 104 (Beton und zugehörige Produkte) wurde eine Task-Group (TG 6) der TC 51/WG 12 gebildet, um die Forschungsarbeit des EG-Forschungsprogramms zu begleiten oder zu verfolgen, das mit dem Ziel durchgeführt wird die Auswirkungen von Beton auf die natürliche Umwelt, falls es solche gibt, und die poten¬ziellen Auswirkungen zementgebundener Werkstoffe auf die Trinkwasserqualität festzustellen.
Dieser Bericht behandelt ausschließlich die Entwicklungen zu einem Ver¬fahren für eine Leistungsprüfung zur Charakterisierung des Auslaugungsverhaltens von Festbeton zur Anwen¬dung in Kon¬takt mit der natürlichen Umwelt, die offiziell der Europäischen Kommission in EUR 17869 EN [1] von einem Kon¬sortium aus niederländischen/deutschen Instituten vorgelegt wurden.
ANMERKUNG Die Normung von Prüfverfahren für die Verwendung von zementgebundenen Werkstoffen (möglicherweise einschließlich Beton) in Kontakt mit Trinkwasser wird – obwohl im Prinzip nicht fundamental abweichend – innerhalb einer Ad-hoc-Gruppe von CEN/TC 164/WG 3 erarbeitet und in einem anderen Bericht behandelt.
Der Schutz der natürlichen Umwelt sowie der öffentlichen Gesundheit und Sicherheit sind von vorrangiger Bedeutung. Von wesentlicher Bedeutung ist jedoch auch die effiziente und nachhaltige Verwendung natür-licher und sekundärer Materialien/Ressourcen. Viele davon können als Bestandteile von Beton verwendet werden. Die Motivation für die in diesem Bericht beschriebenen Untersuchungen beruhte auf der Notwendig-keit, diese beiden Gesichtspunkte innerhalb des Konzepts nachhaltigen Bauens in ein Gleichgewicht zu bringen.
Cement - Študija značilnih lastnosti izluževanja strjenega betona za uporabo v naravnem okolju
Na pobudo CEN/TC 51 (Cement in gradbena apna) in CEN/TC 104 (Beton in sorodni proizvodi) je bila sklicana delovna skupina (TG 6) TC 51/WG 12 za spremljanje ali sledenje raziskovalnemu delu, ki se izvaja v okviru raziskovalnega programa ES in je predviden za ugotavljanje morebitnih učinkov betona na naravno okolje in morebitnih učinkov cementnih materialov na kakovost pitne vode.
To poročilo obravnava samo razvoj, kot o njem uradno poroča konzorcij nizozemskih in nemških inštitutov Evropski komisiji v EUR 17869 EN [1], ki vodi do metode preskusa proizvodnih lastnosti za opis lastnosti izluževanja strjenega betona za uporabo v stiku z naravnim okoljem.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST-TP CEN/TR 16142:2011
01-julij-2011
&HPHQWâWXGLMD]QDþLOQLKODVWQRVWLL]OXåHYDQMDVWUMHQHJDEHWRQD]DXSRUDERY
QDUDYQHPRNROMX
Concrete - A study of the characteristic leaching behaviour of hardened concrete for use
in the natural environment
Zement - Studie zum charakteristischen Auslaugverhalten von Festbetonen zur
Verwendung in der natürlichen Umwelt
Ta slovenski standard je istoveten z: CEN/TR 16142:2011
ICS:
91.100.10 Cement. Mavec. Apno. Malta Cement. Gypsum. Lime.
Mortar
91.100.30 Beton in betonski izdelki Concrete and concrete
products
SIST-TP CEN/TR 16142:2011 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST-TP CEN/TR 16142:2011
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SIST-TP CEN/TR 16142:2011
TECHNICAL REPORT
CEN/TR 16142
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
March 2011
ICS 91.100.30; 91.100.10
English Version
Concrete - A study of the characteristic leaching behaviour of
hardened concrete for use in the natural environment
Zement - Eine Untersuchung der bezeichnenden
Auslaugungseigenschaften von ausgehärtetem Beton zur
Verwendung in natürlichen Umgebungen
This Technical Report was approved by CEN on 20 December 2010. 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, Netherlands, Norway, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2011 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 16142:2011: E
worldwide for CEN national Members.
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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 First 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 estimates . 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 investigations . 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 reagents . 31
4.1 Materials . 31
4.1.1 General . 31
4.1.2 Requirements for standard specimens as test pieces (P ) and test pieces (P ) . 31
D A
4.1.3 Requirements for precast products (or parts thereof) as test pieces (P ) and (P ) . 33
D A
4.2 Reagents . 33
4.2.1 General requirements . 33
4.2.2 Leachant . 33
4.2.3 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
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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 cumulative 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 component . 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 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 leaching 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 . 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 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) 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
leaching 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
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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 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 of
patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent
rights.
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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 establishing 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 EUR 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 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.
The protection of the natural environment and the public’s 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 to
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 interlaboratory 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 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 conclusions.
The leaching of major components/species, which have no environmental significance (e.g. Ca, Na,
K and SO ) from monolithic hardened concrete is diffusion controlled.
4
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 sensitive 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 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 continuing 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.
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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 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 the 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 investigators.
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 marginal, but
standardized, novel materials for the traditional constituents of concrete, would not significantly affect
concrete’s environmental compatibility.
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 relative 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 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.
Concretes 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 affecting 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 pollution.
Accordingly, within the range of traditional compositions used in the EU Member States, concrete’s
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 continuous 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 concrete’s 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 question 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 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, 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.
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Within this operational framework, standardised leaching tests, whether national or international, have
taken a range of forms:
characterisation;
compliance;
verification;
each of which can be used to evaluate the environmental performance/compatibility of hardened
concrete, under different specified conditions using different assessment criteria. Characterisation
leaching tests consist of an availability (granular or pulverized specimen) procedure and a
sequential/periodic tank (monolithic specimen) procedure which together provide the means for
discriminating between the several transport processes such as:
dissolution;
wash-off;
diffusion;
and for predicting the rate of leaching and long term behaviour of a material.
In addition, physical characteristics such as tortuosity, which is a measure of the prolonged path along
which leached components have to travel, can be calculated.
Compliance leaching tests consist of single extractions of short duration, generally without agitation, and
which permit a direct comparison with regulatory limits for individual analytical components. Such tests
use the prior output from characterisation tests to establish and optimise their parameters.
Verification leaching tests are essentially second order compliance tests, modified for operation in the
field and used to identify/assess changes in established performance of batches of a material.
A final, and desirable, element in any authoritative procedure designed to evaluate environmental
performance would be the preparation and maintenance of a certified reference material (CRM), for
example, a certified reference concrete, preferably used within the context of a proficiency testing scheme
(PTS), in order to monitor the performance of a laboratory and validate the accuracy of its procedures. In
the case of concrete, the preparation and robust certification of a CRM is unlikely to be either attempted
or to be feasible given the continuous changes in microstructure to be expected, with the likelihood of
associated changes in its leaching characteristics.
Accepting that a concrete CRM is unlikely to be developed, then the preparation of a standard leachate,
again for use within a PTS, would be the minimum expected for validation of laboratory performance.
It should be understood that the complete analysis of a concrete (or any of its constituents) in order to
give a total elemental composition, is generally acknowledged to be of little environmental value and
would be rarely undertaken in testing given that the greater proportion of most analytical components,
whether environmentally significant or not, is known to be insoluble under naturally occurring exposure
conditions.
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Part I
2 Scope of the study
2.1 Summary of three interlaboratory studies (ILS)
As reported in EUR 17869 EN [1], the Dutch/German Project Team (see 6.2) carried out its investigations
in three stages, each stage leading to an interlaboratory study (ILS); the final ILS involved European
participation much broader than the Project Team’s membership.
The starting point for each stage was that a method of short duration, for the basic characterisation of
leaching of inorganic components, should be developed and finally, validated.
A literature survey had indicated that the main transport process from monolithic concrete should be
diffusion controlled and that a diffusion (tank) test, together with a maximum leachability (availability) test
would be required in order to derive effective coefficients of diffusion, in order to be able to predict long-
term leaching behaviour of concrete in the field
2.1.1 First interlaboratory study and its evaluation (ILS #1)
2.1.1.1 Objective
The objective of the first ILS was to assess the effect(s) on the leaching of a range of inorganic
...
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