CEN/TR 16639:2014
(Main)Use of k-value concept, equivalent concrete performance concept and equivalent performance of combinations concept
Use of k-value concept, equivalent concrete performance concept and equivalent performance of combinations concept
This Technical Report provides more detailed information on the k-value concept principles of the equivalent concrete performance concept (ECPC) and the equivalent performance of combinations concept (EPCC) in accordance to EN 206:2013, 5.2.5.
k-Wert-Ansatz, Prinzipien des Konzepts der gleichwertigen Betonleistungsfähigkeit und Konzept der gleichwertigen Leistungsfähigkeit von Kombinationen aus Zement und Zusatzstoff
Utilisation du concept de coefficient k, concept d’équivalence de performance et concept d’équivalence de performance en combinaison
Uporaba koncepta k-vrednosti, koncepta enakovrednega obnašanja betona in koncepta enakovrednega obnašanja kombinacij
To tehnično poročilo zagotavlja bolj podrobne informacije o načelih koncepta k-vrednosti, konceptu enakovrednega obnašanja betona (ECPC) in konceptu enakovrednega obnašanja kombinacij (EPCC) v skladu s standardom prEN 206:2012, 5.2.5.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-april-2015
Uporaba koncepta k-vrednosti, koncepta enakovrednega obnašanja betona in
koncepta enakovrednega obnašanja kombinacij
Use of k-value concept, equivalent concrete performance concept and equivalent
performance of combinations concept
k-Wert-Ansatz, Prinzipien des Konzepts der gleichwertigen Betonleistungsfähigkeit und
Konzept der gleichwertigen Leistungsfähigkeit von Kombinationen aus Zement und
Zusatzstoff
Utilisation du concept de coefficient k, concept d’équivalence de performance et concept
d’équivalence de performance en combinaison
Ta slovenski standard je istoveten z: CEN/TR 16639:2014
ICS:
91.100.30 Beton in betonski izdelki Concrete and concrete
products
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
TECHNICAL REPORT
CEN/TR 16639
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
March 2014
ICS 91.100.30
English Version
Use of k-value concept, equivalent concrete performance
concept and equivalent performance of combinations concept
Utilisation du concept de coefficient k, concept k-Wert-Ansatz, Prinzipien des Konzepts der gleichwertigen
d'équivalence de performance et concept d'équivalence de Betonleistungsfähigkeit und Konzept der gleichwertigen
performance en combinaison Leistungsfähigkeit von Kombinationen aus Zement und
Zusatzstoff
This Technical Report was approved by CEN on 26 November 2013. It has been drawn up by the Technical Committee CEN/TC 104.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United
Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2014 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 16639:2014 E
worldwide for CEN national Members.
Contents Page
Foreword .3
0 Introduction .4
0.1 General .4
0.2 Task Group 5 .4
0.3 k-value concept .4
0.4 ECPC and EPCC.4
1 Scope .5
2 k-value concept .6
2.1 k-values in EN 206:2013 .6
2.2 Use of k-values in the member states .6
2.3 Procedure for using the k-value concept .7
2.3.1 Principle of the k-value concept .7
2.3.2 Method of calculation .8
2.3.3 Example for determination of k . 10
2.3.4 Further recommendations for the application of the k-value . 12
2.3.5 Example for establishing a general concept using the k-value concept . 12
2.4 Application of k-value concept by the users . 14
2.4.1 General . 14
2.4.2 Example for concrete mix design applying the k-value concept . 14
3 Equivalent concrete performance concept (ECPC) . 15
3.1 General . 15
3.2 Dutch Method . 15
3.2.1 Definitions . 15
3.2.2 Procedure and criteria for assessment of durability aspects . 17
3.2.3 Test methods . 22
3.2.4 Quality assurance . 23
3.3 Recommendations for the application of ECPC . 24
3.4 Additional information to the use of the Dutch method . 25
4 Equivalent performance of combinations concept . 26
4.1 General . 26
4.2 UK method . 27
4.3 Irish method . 28
4.4 Portuguese method . 29
4.5 Recommendation for application of EPCC . 30
4.6 Additional information the UK method . 30
4.6.1 Annexes from BS 8500-2 relating to conformity control of combinations . 30
4.6.2 How this works when specifying concrete to BS 8500 . 35
4.7 Additional information to the Irish method . 39
4.8 Additional information to the Portuguese method . 41
Annex A (informative) Replies to the k -value questionnaire of CEN/TC 104/SC 1/TG 5 . 47
A.1 General questionnaire . 47
A.2 Addition to answer of Finland . 57
Bibliography . 60
Foreword
This document (CEN/TR 16639:2014) has been prepared by Technical Committee CEN/TC 104 “Concrete
and related products”, the secretariat of which is held by DIN.
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.
0 Introduction
0.1 General
This report outlines the current understanding of the use and application of three concepts used within
EN 206:2013 for Type II additions to concrete. These are the k-value concept, the Equivalent Concrete
Performance Concept (ECPC) and Equivalent Performance of Combinations Concept (EPCC).
Within 5.2.5 of EN 206:2013 k-values are given for fly ash and silica fume and a recommended k-value for
GGBS as well as general principles for the ECPC and the EPCC concepts. It is also stated in EN 206:2013
that modifications to the rules of application of the k-value concept are permitted if ‘suitability is established’.
As stated within EN 206:2013 the establishment of suitability should result from provisions valid in the place of
use of the concrete. In order to further explain the three concepts and to give guidance to the regulation
writers and users of these concepts, this report provides background information and an overview of these
concepts and rules of application as used within Europe.
0.2 Task Group 5
CEN/TC 104/SC 1 created Task Group 5 (TG 5) “Use of Additions” and assigned them the task to update
EN 206-1:2000, 5.2.5 as part of the revision of EN 206-1. Because of the publication of product standard
EN 15167-1 for ground granulated blastfurnace slag (GGBS), TG 5 was also asked to include rules for GGBS.
CEN/TC 104/SC 1 passed various resolutions instructing TG 5 that it should implement the EPCC and ECPC
concepts and the existing k-value concept for use of additions at the concrete mixer.
The rules for the use of type II additions in concrete according to EN 206:2013 are given in 5.2.5 “Use of
additions”. For two additions, fly ash and silica fume, specific requirements for their use with k-values are
given. In this prescriptive k-value concept for concrete mix design, the defined rules are on the safe side and
cover all possible variations for the possible permutations of cement and addition. An alternative option is the
use of ECPC and EPCC concepts. Their principles are described in EN 206:2013, 5.2.5.3 and 5.2.5.4 while
examples for the assessment using these concepts are given in this CEN/TR. The rules for these performance
concepts should also be safe and lead to a more efficient use of additions.
0.3 k-value concept
With respect to the k-value concept in EN 206:2013, it was agreed that for fly ash and silica fume prescriptive
k-values and cement substitution rates will be given which are proven to be on the safe side. Although the
k-value concept for GGBS is included in some national regulations (see /2/) only a recommended value is
given in EN 206:2013 due to limited practical experience. In national provisions, however, modifications to the
rules of the k-value concept may be applied where their suitability has been established, e.g. higher k-values,
increased proportions of additions, other additions (including type I), combinations of additions and other
cements than those normally permitted. In this report the derivation of the prescriptive k-value approach is
explained. The report also describes how the k-value concept should be applied by users such as the
concrete producers.
0.4 ECPC and EPCC
The equivalent performance concepts, ECPC and EPCC, for the use of additions may be applied where
suitability has been established. In countries where ECPC and EPCC are applied, nearly always, GGBS as
addition to concrete is used under these concepts. This report describes how the ECPC and EPCC are
applied in some European countries.
1 Scope
This Technical Report provides more detailed information on the k-value concept principles of the equivalent
concrete performance concept (ECPC) and the equivalent performance of combinations concept (EPCC) in
accordance to EN 206:2013, 5.2.5.
2 k-value concept
2.1 k-values in EN 206:2013
The k-value concept has been established for a number of years in a number of countries and was therefore
implemented in EN 206-1 for fly ash and silica fume. In CEN/TC 104/SC 1 report N 278 (June 1996) the
background was given to the application of k-value concept with fly ash concrete [1]. Later this concept was
also applied for concretes containing silica fume and in some member states k-values for concretes with
ground granulated blastfurnace slag (GGBS) are given in national application documents.
In EN 206:2013 prescriptive k-values are given for fly ash and silica fume and a recommended one for GGBS.
These k-values allow the use of these additions in concrete throughout Europe with a restricted range of
cement types within the requirements of the standard without any further verification procedure, i.e. without
further testing except for the normal quality control for the concrete. In a prescriptive concept for concrete mix
designs, the defined rules shall be on the safe side and cover all possible combinations of materials and
variations for the given addition.
The k-value concept is a prescriptive concept. It is based on the comparison of the durability performance (or
strength as a proxy-criterion for durability where appropriate) of a reference concrete with cement “A” against
a test concrete in which part of cement “A” is replaced by an addition as function of the water/cement ratio and
the addition content. With the proof of durability indirectly the proof for the exposure classes is given.
The k-value concept permits type II additions to be taken into account:
— by replacing the term “water/cement ratio” with “water/(cement + k * addition) ratio” and;
— the amount of (cement + k * addition) shall not be less than the minimum cement content required for the
relevant exposure class.
When part of Cement “A” is replaced by an addition, the limiting values that have to be applied are those that
would apply for Cement “A”.
The rules of application of the k-value concept for fly ash conforming to EN 450-1, silica fume conforming to
EN 13263-1 and ground granulated blast furnace slag conforming to EN 15167-1 together with cements of
type CEM I and CEM II/A conforming to EN 197-1 are given in corresponding clauses in EN 206:2013.
Modifications to the rules of the k-value concept may be applied where their suitability has been established
(e.g. higher k-values, increased proportions of additions, other additions (including type I), combinations of
additions and other cements than permitted.
2.2 Use of k-values in the member states
The use of k-values for type II additions in concrete has developed differently across the European member
states over years. Within the revision work of EN 206:2013 member states experience was compiled with a
series of differing enquiries. In 2007 a “Survey of National requirements used in conjunction with EN 206-
1:2000” was published [2]. For the use of additions this enquiry was focused to the regulations for different
classes of LOI for fly ash, environmental compatibility and the use of k-values, especially for fly ash and silica
fume. Five countries responded on the use of k-values for GGBS.
In March 2007, CEN/TC 104/WG 15 presented the results of a survey on the “Use of GGBS as a type II
addition in concrete to EN 206-1”. Eight countries reported on the use of GGBS and it was found that GGBS is
used as type II addition under the ECPC, EPCC and the k-value principles. However, the amount used based
on the k-value concept is relatively limited and this experience is confined only to some Nordic countries [3].
Within the revision work of 5.2.5 “Use of additions” in EN 206:2013, TG 5 also prepared an enquiry on the use
of k-values for additions [4] focusing the experience with the different additions, the k-values and the
determination of these k-values. In total 12 countries answered to the enquiry. Three countries do not use the
k-value concept as they are using existing performance concepts and one country does not use the k-value
concept for GGBS resulting in nine countries with regulations for using GGBS with the k-value concept. The
answers of the enquiry can be compiled as follows:
— The k-value was mostly established based on results of research work and experience.
— The compressive strength is mostly evaluated after 28 days on concrete samples (9 countries) or mortar
(1 country).
— Where the k-value was determined the relationship between the compressive strength and water/cement-
ratio of concrete samples was used.
— The type of cement and the maximum proportions of additions permitted vary widely in the National
regulations, from the use with CEM I only to the use with all cements where the additions are also used in
cement.
— Fly ash is used with more cement types than silica fume and GGBS using the k-value concept.
— k-values for fly ash vary from 0,2 to 0,8, those for silica fume from 1,0 to 2,0 and those for GGBS from 0,4
to 1,0.
— Where k-values had been determined the durability aspects had also been taken into account.
— Most of the countries have experience with k-value concept for fly ash and silica fume, only a few
countries use the k-value concept for GGBS.
The single answers to the TG 5 enquiry are given at the end of this report.
2.3 Procedure for using the k-value concept
2.3.1 Principle of the k-value concept
Type II additions contribute to concrete properties by various mechanisms. Their influence on concrete
properties depends on the characteristics of the individual material properties, on the age of concrete, on the
ambient conditions (temperature, humidity) and various other parameters. To take into account these effects
in the concrete mix design, the k-value method uses the relationship between the water/cement ratio and the
strength of concrete. The concept was introduced by Iain A. Smith for the first time in 1967 for the design of fly
ash concretes with fly ash amount up to 25 % [5] and has developed further on.
Based on the established concept of EN 206-1 and related Eurocodes the concrete mix design is based on
the 28 days strength of concrete. Consequently the standardised prescriptive k-value for a concrete addition is
related to this age. Nevertheless, when a k-value has to be defined, the durability of concretes shall be
considered for the relevant exposure classes.
In concretes containing type II additions, the term “water/cement ratio” is replaced with
“water/(cement + k · addition)” ratio. The factor k indicates the contribution of the addition in concrete
compositions reaching the same strength like the reference concretes without addition.
When the condition of equal strength is assumed, Formula (1) is fulfilled for a specific k-value.
ω w / c+⋅ka (1)
( )
o aa
When these parameters have been determined for equal strength, k can be calculated;
k=(w /ω −c )/ a (2)
a o a
=
or if normalized to the cement content c of the concrete with addition
a
k=(ω /ω −1)/(a / c ) (3)
a o a
where
ω is the water/cement ratio of reference concrete without addition;
o
w is the water content of the concrete with addition;
a
c is the cement content of the concrete with addition;
a
a is the addition content;
ω is the water/cement ratio of concrete with addition (w /c ).
a a a
In prescriptive concrete design methods using the k-value concept, the constant k reflects the maximum value,
which could be used to prove that the water/(cement + k · addition) ratio of the concrete does not exceed the
maximum water/cement ratio as defined for the respective exposure class. It does not give any information
about the effective performance of the used addition in the individual concrete mix.
When evaluating the results of different sets of concrete tests, various k-values could be determined as the
efficiency of a concrete addition is dependent on a number of parameters (e.g. quality and properties of
addition, amount of addition, cement type and properties, water/cement ratio, age, temperature, etc.). The
calculation of k-values indicating the efficiency of a concrete addition is usually performed by the comparison
of the water/cement ratio vs. compressive strength relationship for references concretes without addition and
concretes with addition. For determining the efficiency of an addition, all concretes of a data set calculating k
shall be made of the same cement.
2.3.2 Method of calculation
The method of calculating k-values is generally applicable to type II additions according to EN 206:2013. The
k-value concept is based on the comparison of the performance of a reference concrete with cement “A”
against a test concrete in which part of cement “A” is replaced by an addition as function of the water/cement
ratio and the addition content.
The method described in the following, is based on the Smith method developed for fly ash in 1967 [5]. The
basis for the calculation of k-value is based on the water/cement ratio vs. strength relationship of concretes
with the same content of addition. The determination should preferably not be done on the results of single
concretes mixes, but by a set of data. This allows a more precise determination of the water/cement ratio vs.
strength relationship. To arithmetically describe that relationship, different empirical formulae could be used.
Usually a linear relationship gives a good approximation of strength in restricted ranges of water/cement ratio
Compressive strength = a - b · water/cement ratio
But also other nonlinear approaches (e.g. Abrams law [6, 7], could be used [8, 9]. The values of the factor “k”
may also be given by technical feedback. E.g. in France, where the k-value concept is used for Type II and
some type I addition (limestone and siliceous filler), the values are derived from the Bolomey method [10] and
adjusted by experience.
Comparison of the different approaches shows that there might be slight differences in the calculated k-
values, but the level of the results is similar. The variances in the measured compressive strength results have
a much higher impact on the calculated values [11].
Key
1 addition with content a
2 reference
Y strength
Figure 1 — Principle of k-value determination (shown for w / (c + a))
Strength vs. water/cement – relationship of reference concrete:
f= AB−⋅ω
o o oo
For a selected c/a ratio, the linear approximation can be assumed also for the correlation f versus w / (c + a)
a
as shown by the following formula:
f =A −B ⋅(w /(c+ a))
a a a
When a functional relationship between water/cement ratio and compressive strength based on test results
has been determined for reference concretes without addition and concretes with a defined addition/cement
ratio respectively both formulae are set to be equal;
ff=
o(reference) a(addition)
f = f ⇒ A − B ⋅ω = A − B ⋅ w /(c+ a) (4)
o a o o o a a a
ω w / c+⋅ka ⇒ w ω⋅ c+⋅ka (5)
( ) ( )
o a a o
A − B ⋅ω = A − B ⋅ω ⋅(c+ k⋅ a)/(c+ a) (5) substituted in (4)
o o o a a o
or A− B⋅ωωA− B⋅ ⋅ 1+⋅k ac/ /1+ ac/
( ) ( )
o oo a a o
This follows the principle that the parameter k has to be determined on the basis of equal strength. Now, using
Formula (3) and necessary arithmetic transformations, k can be determined. In this way of calculation, k will
not be a single value but will be a parameter in functional dependence of the water/cement ratio of the
reference concretes (ω ).
o
(A − A )⋅(1+ a / c) 1 B ⋅(1+ a / c) 1
a o o
k= ⋅ + −1⋅
B ⋅ a / c ω B a / c
a o a
=
= =
where
ω water/cement ratio of reference concrete without addition
o
ω water/cement ratio of concrete with addition (w /c )
a a a
w 3
a water content of concrete with addition [kg/m ]
c 3
a cement content of concrete with addition [kg/m ]
a
content of addition [kg/m ]
f , f compressive strength of concretes [MPa]
0 a
A , A , B , B empirical coefficients of the linear relations between water-cement ratio and strength of the reference
0 a 0 a
concrete and the concrete with additions
2.3.3 Example for determination of k
For demonstrating the calculation of k, an example is used with concretes containing a fly ash content of 20 %
by mass (related to cement plus fly ash). Figure 2 shows the relationship between water/(cement + fly ash)
ratio and strength for the concretes with fly ash and the reference concretes without addition which have been
used for the calculation.
Key
1 0 % fly ash
2 20 % fly ash
X water / (cement + fly ash) ratio
Y compressive strength at 28 days [MPa]
Figure 2 — Example for strength vs. water / (cement + fly ash) relationship
f =91,64−95,20⋅ω
o o
f=101,8−124,6⋅water/ cement+flyash with fly ash/cement = 0,25 (20 % fly ash)
( )
f
(101,8−91,64)⋅+(1 0,25) 1195,20⋅+(1 0,25)
k ⋅+ −⋅1
124,6⋅0,25 ω 124,6 0,25
o
⇒= k 0,408⋅1/ω−0,180
o
With this term, the k-value can be plotted as function of ω (see Figure 3).
o
For a given ω , k can be calculated, for example: ω = 0,50 k = 0,64
o o
ω = 0,60 k = 0,50
o
Key
1 20 % fly ash
Y k-value at 28 days
Figure 3 — k-value plotted as function of water/cement ratio ω of reference concrete
o
Control
Alternative 1
Select a compressive strength, e.g. 35 MPa
f= AB−⋅ωω= 35= 91,64−95,20⋅
o o o o o
⇒=ω (91,64−35)/95,20 0,595
o
f=A− B⋅+wc/ f=35=101,8−124,6⋅+wc/ f
( ) ( )
f ff
⇒ wc/(+ f) (101,8−35)/124,6 0,536
k=(ω /ω −1)/( f / c) with ω w/(c+ f)⋅+(1 fc/ ) (see box in Figure 1)
f o
f
=
= =
=
=
k 0,536(1+0,25)/0,595−1 /0,25 0,504
[( ) ]
Alternative 2
Select a w/c ratio, e.g. ω = 0,50
o
k ω= 0,50= 0,408/0,50−=0,180 0,636
( )
o
f ω= 0,50= 91,64−95,20⋅=0,50 44,0MPa
( )
oo
f A− B⋅ω⋅ 1+⋅kf / c /1+ f / b
( ) ( )
f f fo
101,8−124,6⋅0,50⋅+1 0,636⋅0,25 / 1+0,25 44,0MPa
( ) ( )
NOTE The example origins from concretes with fly ash as addition therefore in the formulae the amount of fly ash is
represented by the symbol f.
2.3.4 Further recommendations for the application of the k-value
For the application of the k-value concept the following recommendations should be considered:
— k-values should be calculated only for water/cement ratios in the range investigated (no extrapolation).
— Beside cement and addition all other concrete components have an effect on the strength of concrete.
Therefore keep them constant.
— If a constant workability is preferred, where necessary use a water reducing admixture (plasticiser) to
ensure no excessive air is entrained.
— Ensure the variability in the determination of compressive strength is as low as possible because any
scattering is magnified in the calculation of the k-value.
2.3.5 Example for establishing a general concept using the k-value concept
As an example the principles of the procedure of introducing the k-value for fly ash in the 1990s is
demonstrated. The results of this approach were included in EN 206-1:2000.
The determination of the prescriptive k-value is performed in two steps. In the first step, k-values are
calculated from concrete tests according to the procedure and recommendation reported above. In the
concrete tests all relevant parameters (cement type, strength class, quality of addition, water/cement ratio,
etc.) should be considered to allow the definition of a generally applicable prescriptive k-value. Figure 4
demonstrates the range of calculated k-values resulting from concrete strength tests using various
combinations of different cements and a fly ash. The fly ash used for durability test as shown in Figures 5 and
6 is representative for a fly ash according to EN 450-1. It had been selected from pre-tests out of a range of
more than 30 fly ashes. As shown in Figure 4 a prescriptive k-value of 0,4 was derived taking into account a
certain safety margin [12].
= =
=
= ⇒=
Key
1 range of various cement and fly ash combinations
X age of concrete, [days]
Y k-value [–]
Fly ash content 20 % of total binder (f / c = 0.025)
Figure 4 — Determination of a prescriptive k-value from concrete test results [12]
In a second step, concretes with a composition using k = 0,4 or very similar k-value were produced.
In this case (Figures 5 and 6) the fly ash was taken into account by a k-value of 0,5 on the w / (c + k · f) ratio.
Again all relevant parameters (cement type, strength class, quality of addition, water/cement ratio, etc.) were
considered in the testing program. With these concretes it was proven that the critical durability requirements
for a prescriptive concept (e.g. freeze thaw resistance and carbonation in that case) are fulfilled (Figures 5 and
6).
Weight loss after 100 freeze–thaw cycles (wt. %)
Figure 5 — Results from freeze–thaw testing verifying the suitability of a prescriptive k-value [12]
Figure 6 — Results from carbonation tests verifying the suitability of a prescriptive k-value [12]
2.4 Application of k-value concept by the users
2.4.1 General
Permitted k-values and cement substitution ratio (a/c) have to be taken from EN 206:2013 or derived from
national regulations. For the concrete mix, the maximum water/cement ratio (w/c) and minimum cement
content will be specified as a result of the evaluation of the use and conditions.
2.4.2 Example for concrete mix design applying the k-value concept
a) Basic assumptions for the example:
1) A concrete using a cement type CEM II/A-S for Exposure Class XC4 shall be designed.
2) According to EN 206:2013, Table F1 (informative annex) a minimum cement content of 300 kg/m is
required and a maximum w/c of 0,50 is allowed for that exposure class.
3) Fly ash should be used as concrete addition (k = 0,4) and by that the cement content shall be
reduced to 280 kg/m .
b) Determination of the fly ash content
EN 206:2013, 5.2.5.2.1 defines that the amount of (cement + k · addition) shall not be less than the minimum
cement content required for the relevant exposure class.
( )
c+ k⋅ f ≥ 300 kg/m
By transforming that formula, the minimum fly ash content (f) can be determined by
f≥(300− c)/ k=(300−280)/0,4=50kg/m
For a cement of type CEM II/A the maximum amount of fly ash to be taken into account shall meet the
requirement fly ash/cement ≤ 0,25 by mass.
The maximum amount of fly ash to be taken into account is then
fc≤0,25⋅= 0,25⋅280 70kg/m
3 3
Thus the fly ash content should be in the range between 50 kg/m and 70 kg/m (higher amounts are allowed,
3 3
but not more than 70 kg/m can be taken into account). For this concrete a fly ash content of 60 kg/m was
chosen.
c) Determination of water content
According to EN 206:2013, 5.2.5.2.1, the term “water/cement ratio” (w/c) can be replaced by with the ratio
“water/(cement + k x addition)”. This ratio w/(c + k · f) shall be equal or lower than the maximum allowed w/c
w/(c+⋅kf)≤0,50
By transforming that formula, the minimum water content can be determined by
w≤0,50⋅(c+⋅kf) 0,50⋅(280+0,4⋅60) 152l/m
I.e. the concrete should not contain more than 152 l/m to fulfil the requirements for exposure class XC4.
3 Equivalent concrete performance concept (ECPC)
3.1 General
In 5.2.5.3 of EN 206:2013 the principles of the Equivalent Concrete Performance Concept are introduced. This
concept permits amendments to the requirements for minimum cement content and maximum water/cement
ratio (wcr) when a combination of a specific addition and a specific cement source is used for which the
manufacturing source and characteristics of each are clearly defined. It shall be proven that the concrete has
an equivalent performance especially with respect to its interaction with the environment and to its durability
when compared with a reference concrete in accordance with the requirements for the relevant exposure
class.
In the Netherlands the procedure, criteria and test methods for the assessment of the ECPC are given in the
national guideline CUR-Recommendation 48 (in Dutch) [13]. CUR-Recommendation 48 applies to the
assessment of the suitability of a combination of one or more specific additions and one or more specific
cements for application in concrete. All constituents of cement as mentioned in EN 197-1 with the exception of
Portland cement clinker can be used as additions.
Experience
The ECPC has been used in the Netherlands for the past 15 years for combinations of fly ash and cement
(CEM I or a combination of CEM I and CEM III) and almost 10 years for combinations of GGBS and cement.
The procedures and requirements for combinations of fly ash and cement and also for the combination of
cement with GGBS and fly ash are described in the Dutch assessment procedures for certification BRL 1802
[14]. The assessment procedures follow the principles of CUR-Recommendation 48.
Other systems compliant with 5.2.5.3 of EN 206-1:2000 are in existence, e.g. in Germany as a national
technical approval [15, 16], and in Belgium as a national standard [17].
3.2 Dutch Method
3.2.1 Definitions
The definitions given in CUR-Recommendation 48 are given below.
= =
=
Cement types
Cement types refer to those mentioned in column 2 of Table 1 in EN 197-1:2011.
Specific cement
Cement for which the manufacturing source, cement type and strength class are well defined. If two cements
identical in type and strength class are manufactured in the same factory, a specific label should be added for
identification.
Addition
Finely divided material that complies with the following requirements:
— mentioned as main constituent of cement in EN 197-1 (with the exception of Portland cement clinker),
— physical and chemical properties are well defined and documented,
— proven quality control,
— complies with the requirements in the relevant product standards or guidelines for use in concrete.
NOTE Only additions for which a European or national standard or provisions for the addition valid in place of use,
specific for use in concrete complying with EN 206:2013, are within the scope of the recommendation.
Specific addition
Addition, as defined above, for which the manufacturing source and the production method are well
documented.
Binder content
Sum of the amounts (kg/m ) of cement and addition in the test concrete, manufactured with a cement-addition
combination.
Reference cement
Cement, that complies with EN 197-1 and is permitted for general use in concrete by NEN 8005. Furthermore,
the cement shall have been applied in concrete in the Netherlands during at least 5 years.
Reference concrete
Concrete manufactured with fluvial sand, gravel, water and, if appropriate, an admixture and a reference
cement. The composition complies with the requirements of NEN 8005 (National Provisions) for the applicable
exposure class (see Table 7).
Test concrete
Concrete manufactured with a combination of cement and addition, for which the equivalent performance with
the reference concrete has to be demonstrated. With exception of the binder the nature and dosage of the
other constituents are identical to the reference concrete.
Equivalent concrete performance
In the case that the durability aspects, to be tested according to the recommendation, of the test concrete are
equal or better than those of the reference concrete, the performance of the test concrete is assessed as
equivalent to the reference concrete.
Suitability concrete for application in a specific exposure class
If it is demonstrated following the recommendation that the performance of a test concrete is equivalent to the
reference concrete, the composition of which complies with a specific exposure class, the test concrete is
assessed suitable for this exposure class.
3.2.2 Procedure and criteria for assessment of durability aspects
Durability aspects
To demonstrate the equivalent performance of the test concrete, depending on the exposure class, one or
more of the following durability aspects have to be tested:
— resistance to carbonation,
— resistance to chloride ingress,
— frost-thaw de-icing salt resistance,
— resistance to seawater,
— resistance to sulfates.
ASR is not part of this recommendation. Measures to prevent damage to concrete by ASR are given in CUR-
Recommendation 89 [18]. In addition, measurement of the concrete strength at 7 and 28 days is part of the
assessment of the test concrete.
Other mechanical properties (tensile strength, bending strength, elastic modulus, shrinkage, creep) do not
have to be tested. In structural codes these properties are related to the compressive strength. Since the
composition of cement-addition combinations is similar to that of common cements, the relation between
compressive strength and other mechanical properties will also be similar.
Assessment procedure
Composition of test and reference concrete
The reference concrete should:
— comply with the requirements of NEN 8005 for the applicable exposure class (see Table 7),
— be manufactured with a reference cement belonging to the applicable exposure class in accordance with
Table 1.
— one or more reference cements may be used for testing the different durability aspects.
Table 1 — Reference cement types in relation to the exposure class
Reference cement types
Exposure
Class CEM I CEM II/A-S CEM II/B-S CEM II/A-V CEM II/B-V CEM III/A CEM III/B
XC X X X X X X X
XD X a X
X
XS X a X
X
XF2 + XF4 X X X X X b c
X X
XA2 + XA3 X X
a
slag content ≥ 50 %
b
slag content < 50 %
c
Only for test concrete, manufactured with a combination of slag and cement as binder, with a slag content virtually
identical to that of the reference cement.
In Table 1 those cements have been selected for a particular exposure class that are commonly used in the
Netherlands in this exposure class.
The composition of the test concrete should comply with the following requirements:
— the minimum clinker content shall be 20 % (m/m) for the combination of Portland cement with slag and
25 % (m/m) for other combinations,
— the maximum limestone content of a cement-addition combination shall be 35 % (m/m),
— the binder content shall be equal or larger than the minimum cement content for the applicable exposure
class, as defined by NEN 8005,
— the water/binder ratio (wbr) shall be smaller than or equal to the maximum water/cement ratio (wcr) for the
applicable exposure class, as defined by NEN 8005.
The clinker and/or limestone contents shall be calculated by the method used in EN 197-1 for the main
constituents of cement.
Durability aspects in relation to the exposure class
Only those durability aspects that are relevant for the exposure class need to be tested (Table 2). For
exposure class XA only sulfate resistance is part of the test program. The resistance to other aggressive
components is outside the scope of the recommendation.
Only in the case that the sulfate content of the soil or the water leads to a classification in XA2 or XA3, a test
of the sulfate resistance is mandatory. In all other cases a cement-addition combination can be applied in XA
with only strength testing.
For exposure classes XF1 and XF3 only strength testing is required.
Table 2 — Durability aspects in relation to the exposure class
Exposure Carbonation Chloride Freeze–thaw Seawater Sulfate
Class ingress de-icing salt resistance resistance
XC X
XD X
XS X X
XF2 + XF4 X
XA2 + XA3 X
Suitability related to the exposure class
A test concrete is suitable for application in a certain exposure class if it fulfils the criteria for all durability
aspects relevant to the exposure class.
A test program has been performed to investigate if the equivalent performance depends on the binder
content and water/binder ratio for combinations with fly ash and slag. The resistance to chloride ingress as
tested by the Rapid Chloride Migration (RCM) test was selected to investigate this dependence. For both
additions it has been found that there is no relation between the resistance to chloride ingress and wbr (tested
range: 0,45 – 0,65) at a concrete age of 1 to 3 years (see Figure 7).
Key
1 PC
2 HOC
3 PC + pvla
X wcf
−12
Y
RCM (10 m /s)
Figure 7 — RCM - value after 1 year versus water/cement ratio for Portland cement (PC), slag cement
(HOC) and a combination of Portland cement and fly-ash (PC+pvla)
The concrete composition for each durability test is given in CUR Recommendation 48. In this report only a
summary is given. For testing the effects of chlorides on corrosion, a single concrete composition can be
applied. This is based on a research project related to the RCM test performed in NL. The background is
given in a Dutch CUR report [19].
For the additions fly ash and slag the test for each durability aspect is therefore performed on a single
concrete composition with a certain binder content and wbr. If the test concrete fulfils the requirements for a
certain exposure class, the combination is then allowed for the full range of binder content and wbr as defined
in NEN 8005 for this exposure class (Table 7).
For additions other than fly ash or slag the assessment of CUR Recommendation 48 has to be performed at
both the upper and lower limit of the wbr for the exposure class for which the durability test is relevant (e.g.
chloride penetration for XD and XS).
Criteria for assessment
Basic assumptions
The assessment of durability aspects is based on the comparison of n samples (of the cement and addition)
and the test specimens made from these samples. Approval or rejection is based on the difference in the test
results between the test and reference concrete. The limit value is based on the following principle.
For each durability aspect a relative difference d [%] is defined (at the level of the population) that is
considered unacceptable. In other words, an a
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.
Loading comments...