benchmark for deemed-to-satisfy rules xd

7/25/2019 Benchmark for Deemed-To-satisfy Rules Xd

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BENCHMARK FOR DEEMED-TO-SATISFY RULES (XD, XS)

FORfib-CONGRESS February 2014 MUMBAI

Greve-Dierfeld, S. vonformer Materials Science and Testing (MST), TU Muenchen, Baumbachstr. 7, 81245 Muenchen,Germany.

Gehlen, Ch.Chair of Materials Science and Testing (MST), TU Muenchen, Baumbachstr. 7, 81245

Muenchen, Germany.

Abstract

The current system for specifying and ensuring durability of new concrete structures in standards is

commonly of a prescriptive type. In prescriptive specifications, durability is guaranteed indirectly

by ensuring compliance with limiting values for concrete composition and construction details.

These empirical provisions have typically evolved from local experience and the local

availability of concrete constituents. They are based on the individual preferences on safety without

any type of mathematical or scientific verification. One of the practical results is that there is an

enormous variation in requirements between the various countries all over the world and even in

Europe when close regional proximity is given. However, the different national provisions cannot

be explained on a rational basis and it is likely that they do not lead to a consistent exposure

resistance.

The aim of this work is to perform a benchmark for deemed-to-satisfy rules for the exposure

classes XD and XS. Within the benchmark it is determined which reliabilities against chloride-

induced depassivation of rebars can be expected if the deemed-to-satisfy rules of different countries

are considered. This includes not only calculations mainly based on short term laboratory data, but

also an independent assessment of existing structures.

The calculated reliability ranges determined are compared with the target reliabilities proposed by

current specifications and, based on the above comparison, a proposal for improving deemed-to-

satisfy rules and specifications is made.

Keywords: Durability, deemed-to-satisfy rules, performance based rules, chloride, reliabilitydesign, assessment of existing structures

1

Introduction

In prescriptive specifications durability with respect to chloride induced corrosion is guaranteed by

ensuring compliance with limiting values for:

- maximum w/c-ratio, minimum cement content, limits on the permitted types of cement andtheir components and / or limits for the compressive strength, together with

- a minimum concrete cover mostly combined with an allowed tolerance, both in dependenceof

- exposure class, giving the classified degree of severity of the environmental load.Although globally these limiting values vary over a wide range of values and although these

values are often combined differently, they all follow the same goal: provide enough resistance in

order to avoid chloride induced corrosion with sufficient reliability.


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Hence, one aim of the benchmarking was to determine whether the limiting values and their

various combinations fulfil the target reliabilities of current specifications. In order to verify the

reliability provided by the deemed-to-satisfy rules, the initial goal was to

-identify those prescriptive values that mainly affect the material performance and to relatematerial performance (under constant, standardized conditions) to the prescriptivespecifications.

-transfer the definitions of the exposure classes in meso-climatic environmental loads in orderto describe the material performance under exposure.

2 Background: model, parameters and data used for the benchmark

task

2.1Mathematical model

Diffusion, permeation and convection are the means by which chlorides penetrate concrete.

Assuming, diffusion to be the prevailing transport process, the following mathematical expressionis used to describe the rate at which chlorides penetrate the concrete, Eq. (1).

=

=

t

tD(t)Dwitht

C

C1erf)t(D2t)x(C, 00app

s

1-

app (1)

Here x in [m] is the depth with a defined critical chloride content (C = Ccrit) at time t, Cs is the

chloride surface concentration [wt.%/cement],Dapp(t)in [m2/s] is the apparent diffusion coefficient

at time t [s],D0is the diffusion coefficient measured at a reference time t0and in [-] is the agingexponent, giving the decrease over time of the apparent diffusion coefficient.

This is a simple transformation of the well-known expression, where the chloride content

C(x,t)[wt.%/cement] at depthxand time tis given by Eq. (2).

t)t(D2

xerfC)t,x(C

app

s

= (2)

The initial chloride content (Ci) can be included in both the above equations (ISO 16204, 2012).

One can conclude that the rate at which chlorides penetrate concrete is governed by the diffusivity

of the concrete (material) and concentration of the chloride load (environment).

2.2 Data

Material

The apparent chloride diffusion coefficient is used to describe the diffusivity of the concrete. Insaturated concrete, the apparent diffusion coefficient is mainly controlled by the pore structure

(amount, size and tortuosity) and is less affected by ionic interactions.

Usually, the chloride diffusion coefficients for specific concrete compositions are either

determined in accelerated tests or in short term tests both under different experimental condition.

Mostly, non-steady-state diffusion coefficients are determined. In the accelerated tests methods,

migration coefficients are determined by accelerating the chlorides in an electric field, where

transport by diffusion is negligible (e.g. NT BUILD 492, 1999), or the diffusion coefficients are

determined with increased chloride concentrations (e.g. NT BUILD 443, 1995). In short term tests,

diffusion coefficients are determined under natural chloride load (e.g. DD EN/TS 12390-11,

2010). The migration coefficient is assumed to correlate well with the diffusion coefficients at early

ages (Tang et al. 2010, Gehlen, 2000, Tang, 1996).

In Fig. 1 (left) a summary of migration coefficients (t0= 28 d) in dependence of the type ofcement and w/c-ratio is given since these two parameters strongly affect the pore structure of the


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concrete. The amount of binder, providing a minimum for sufficient compaction is guaranteed, as

well as by the type, shape and size of aggregate are less important (Lay & Schiel, 2002). The

migration coefficients where derived from (Bjegovic et al., 2012, Heinz et al., 2011, Mller &

Severins, 2009, Mller et al., 2009, Visser & Nijland, 2009, Gruyaert et al., 2009, Wiens, 2005,Lay & Schiel, 2002, Gehlen, 2000, Chrisholm & Lee, 2001). In Fig. 1 (right) the correlation

between chloride migration coefficient and chloride diffusion coefficient according to (NT BUILD

443, 1995) and (DD EN/TS 12390-11, 2010) is shown (Tang et al., 2010).

Fig. 1 Chloride diffusion coefficient at time t0= 28 d (left), correlation between chloride migration and

chloride diffusion coefficient (Tang et al, 2010) (right).

In Fig. 1 the symbols represent the mean value of the chloride migration coefficients determined by

various authors. An exponential function was fitted to the mean values. Due to the random scatter

for CEM II/A,B-LL, CEM II/A,B-V and CEM III/A,B (A: full symbols, B: empty symbols) one

curve was fitted to both cement clinker contents (A and B).

In Fig. 1 (left) it can be seen that chloride migration coefficients increase exponentially with

w/c-ratio. At the same w/c-ratio, concretes with high contents of ground granulated blast-furnace

slag (GGBS) show low chloride migration coefficients due to their low porosity (CEM III).Generally, the chloride migration coefficients decrease continuously from 30 wt.% GGBS content

up to 50 wt.% GGBS (Lay & Schiel 2002). Concretes with silica fume (SF) (CEM II/A-D)

possess low chloride migration coefficients mainly due to the beneficial filler effect of SF. The

same holds for concretes with fly ash (FA) (CEM II/A-V, CEM II/B-V), but with less effect. The

highest chloride migration coefficients are possessed by concretes with limestone (LS) which is

due to the increased porosity - especially if more than 15 wt.% is used (Lay & Schiel, 2002).

CEM I concretes show slightly lower migration coefficients than CEM II/A,B-LL concretes.

The chloride diffusion coefficient decreases due to ongoing hydration and reaction products

that lead to changes in the pore structure. The decrease in chloride diffusion coefficient is

represented by the aging exponent.

The aging exponent under constant saturated conditions is mainly affected by the type of

cement and its components (Gehlen, 2000). Ordinary Portland cement concretes (OPCC), andconcretes with components like LS (CEM II/A, B-LL), SF (CEM II/A-D) or low contents of GGBS

(CEM II/A, B-S) have the lowest aging exponents ( ~ 0.30), due to the negligible ongoinghydration and the low binding capacity. Higher aging exponents are possessed by concretes with

higher amounts of GGBS (CEM III) due to the ongoing latent hydraulic reaction and the higher

binding capacity ( ~ 0.45). Concretes with fly ash (CEM II/A, B-V) show the highest aging

exponent due to the ongoing puzzolanic reaction and the high binding capacity ( ~ 0.60). Thevalues for the ageing exponents given are derived from (Caballero et al., 2010, Polder et al., 2010,

Markeset & Skjlsvold, 2010, Nokken et al., 2006, Stanish & Thomas, 2003, Gehlen, 2000).

Taking into consideration aging behaviour of different types of cement: concretes with lower

resistances (with higher migration coefficients or diffusion coefficients, respectively) determined inshort-term tests may have a higher long-term resistance. Thus, from the migration coefficients of

Fig. 1, the apparent diffusion coefficients at time t = 50 years where calculated with the aging

0

5

10

15

20

25

30

0.4 0.45 0.5 0.55 0.6

DRCM

[10-12m2/s]

w/c-ratio [-]

CEM II/A,B-LL

CEM I

CEM III/A,B

CEM II/A,B-V

CEM II/B-S

CEM II/A-D

05

10

15

20

25

30

0 5 10 15 20 25 30

Dapp

(t0

)[10-12m/s]

DRCM(t0) [10-12 m/s]

prEN/TS 12390-11

NT BUILD 443


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function (Eq. (1) right) and the aging exponents for the specific type of cement introduced above,

see Fig. 2.

Fig. 2 Apparent chloride diffusion coefficients at time t= 50 years, calculated for the cement types of Fig.

1 (left) using Eq. (1) (right) and the aging exponents introduced above.

Environment

The chloride surface concentration strongly affects the concentration gradient. The chloride surface

concentration under saturated conditions depends on the chloride concentration of the ambient

solution as well as on the adsorption and binding capacity of the concrete. Especially under

immersed conditions, the chloride surface concentration is affected by the type of cement. The

surface concentration of concretes with GGBS or FA is increased due to their higher binding

capacity (higher C3A, C4AF contents). For concretes with OPC or additives like SF, the chloride

surface concentration is decreased due to the lower binding capacity. Furthermore, the chloride

surface concentration increases with increasing w/c-ratio (adsorption). The amount of binder has

less effect.

The environmental load is loosely defined in the exposure classes by the description of the chloridesource and humidity conditions. The effect of chloride load on material performance is governed

by the chloride surface concentration Cs. The effect of moisture content is included in the surface

concentration Csand the aging exponent .The chloride surface concentration under real exposure conditions is subject to systematic

spatial variations documented in dependence of the distance of the concrete surface to the chloride

source in urban (DARTS 2004) as well as marine environments (Markeset & Skjlsvold, 2010,

Helland et al., 2010, Wall, 2007, Nokken et al., 2006, Ghods et al., 2005, Fluge et al., 2001), Fig. 3.

Herein, our own data (black symbols) is included derived from four car parks in Munich (XD3) and

from exposed specimens in Helgoland (XS3). In Fig. 3, the chloride surface concentration

determined from field exposure (meso-climatic conditions) is shown in dependence of the distance

to the chloride source to the concrete surface and related to the exposure classes.

Fig. 3 Chloride surface concentration in dependence of the distance to chloride source for urban (DARTS,

2004) (left) and marine environments (Markeset & Skjlsvold, 2010, Helland et al., 2010, Wall, 2007,

Nokken et al., 2006, Ghods et al., 2005, Fluge et al., 2001) (right) meso-climatic conditions both in wt. % percement.

0

1

2

3

4

5

0.4 0.45 0.5 0.55 0.6

Dapp

(t=50)[10-12m

2/s]

w/c-ratio [-]

CEM II/A,B-LL

CEM I

CEM III/A,B

CEM II/A,B-V

CEM II/B-S

CEM II/A-D

0

1

2

3

4

5

6

0 1 2 3 4 5

Chloridesurface

concentration[wt.%/c.]

Distance to chloride source [m](height above road)

XD1

XD2

horizontal distancefrom road:

0.5 m

2.0 m

carprarks

XD3

0

1

2

3

4

5

6

-5 0 5 10 15 20 25

Chloridesurface

concentration[wt.%/c.]

Distance to chloride source [m]

XS1XS3XS2

< MLT ~ wave crest

CEM I+FA

CEM I

CEM I


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In Fig. 3 (left) for wet, rarely dry conditions (XD2) no systematic spatial variability is considered.

For cyclic wet and dry conditions (XD3) and in moderate humidity (XD1), a constant decrease with

the distance to the chloride source occurs.

In Fig. 3 (right) for permanently submerged conditions (XS2) no systematic spatial variabilityis reported. The chloride surface concentration corresponds with the salinity of the ambient

solution. For tidal and splash zone (XS3), the chloride surface concentration decreases rapidly with

the distance to the chloride source. In the spray zone (XS1), a further decrease in chloride surface

concentration occurs. Furthermore, it can be seen that differences due to chloride binding and

adsorption in the exposure classes XS3 and XS1 disappear against the background of random

spatial variability.

The effect of humidity is empirically included in the lower surface concentration and is partly due

to the reduced adsorption. Furthermore, the diffusion process is reduced in partly saturated concrete

(spray zone: XD1, XS1), which results in an increased aging exponent (Fig. 4). The degree of

saturation in dependence of relative humidity decreases with increasing pore radius. Because of

this, higher differences in the aging exponents for OPCC (more dry) concretes are reported, smallerdifferences are reported for FA concretes (less dry) see Fig. 4 (cf. left with right). The aging

exponents in Fig. 4 are taken from (Caballero et al., 2010, Polder et al., 2010, Markeset &

Skjlsvold, 2010, Nokken et al., 2006, Stanish & Thomas, 2003, Gehlen, 2000).

Fig. 4 Aging exponents for nominally saturated conditions (XS2, XS3, XD2, XD3) (left) and partly

saturated conditions (XS1, XD1) (right) from (Caballero et al., 2010, Polder et al., 2010, Markeset &

Skjlsvold, 2010, Nokken et al., 2006, Stanish & Thomas, 2003, Gehlen, 2000).

Furthermore, it is known, that temperature affects binding capacity and ion mobility and hence the

diffusion process. The effect of temperature on the diffusion coefficient is accounted for by the

Arrhenius function with the regression parameters given in (fib, 2006).At least, deviations from Ficks second law of diffusion for example due to leaching,

capillary suction and interactions with effects like carbonation in the exposure classes XD3, XS3

have to be taken into consideration. One possibility is to use an apparent chloride surface

concentration calculated for the surface at x = 0. Another possibility is to use the highest chlorideconcentration (Cs,x) in the depth xand to deduct the depth xfromx, as applied here.

Summary

The prescriptive values minimum w/c-ratio and recommendations with respect to the type of

cement and its components are the decisive parameters that govern material resistance. The

cement content, provided a minimum for sufficient compaction is guaranteed, is of less

importance. The effect of compressive strength is already given by the w/c-ratio and may be

regarded as supplementary control measure.

An increase in w/c-ratio leads to an increased chloride diffusion coefficient and higher

chloride surface concentrations. In contrast, types of cement which yield low diffusion coefficients

lead to high chloride surface concentrations and vice versa. Furthermore, the effect of cement type

0.0

0.2

0.4

0.6

0.8

1.0

CEM I

(+ LL, S, D)

CEM I

(+ FA)

CEM III

ageexponent

[-]

0.0

0.2

0.4

0.6

0.8

1.0

CEM I

(+ LL, S, D)

CEM I

(+ FA)

CEM III

ageexponent

[-]

XD2, XD3, XS2, XS3 XD1, XS1


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on material performance is strongly time dependent. Type of cement with low diffusion

coefficients at young ages may possesses higher diffusion coefficients at higher ages.

3

Benchmarking

3.1 Selection of countries

Regarding material performance under immersed conditions (more or less constant), the w/c-ratio

and the type of cement are the decisive parameters that affect material performance. Regarding

material performance under exposure, the decisive parameters are the location (distance to chloride

source, humidity condition and the chloride content of the ambient solution) to be taken into

account when selecting a country.

Thus for the selection of countries, i.e. the respectively national specifications, the following was

considered:

I. diversity in deemed-to-satisfy rules: w/c-ratio, cover, types of cement and the diversity in

construction practice given by the local availability of specific types of cementII. diversity in environmental load (exposure class definition, salinity of seawater,

temperature conditions and frequency of de-icing salt application)

Point I: a significant diversity in deemed-to-satisfy rules in comparison with EN 1992-1-1/EN 206-

1 (EN 1992-1-1, 2002, EN 206-1, 2001) may be found when considering Australia (AUS), United

States of America (USA), Portugal (P), Spain (E) and Great Britain (GB), the Netherlands (NL),

Germany (D), Denmark (DK) and Norway (N). The variety of permitted types of cements and their

combination with w/c-ratio and / or cover are summarized in Table 1.

Table 1Diversity in deemed-to-satisfy rules for structures exposed to chloridesCountry Diversity in deemed-to-satisfy rules and permitted types of cement

Spain (E) CEM III, CEM IV,

CEM II/B-S, B-P, B-V, A-D combined

with a lower cover for one w/c-ratio

Others

combined with a higher cover for

one w/c-ratio

Portugal (P) CEM II/A-D, CEM II/B, CEM III/A, CEM

III/B, CEM IV/A, CEM IV/B, CEM Vcombined with a higher w/c-ratio for one

cover

CEM I, CEM II/A

combined with a lower w/c-ratio forone cover

Great Britain (GB) Groups of types of cement combined with w/c-ratio correlated with cover

The Netherlands (NL) All types of cement; One cover and w/c-ratio within each exposure class

Germany (D) All except: CEM II/B-LL, CEM II/B-L, CEM II/A-W, CEM II/B-W, CEM

IV/A, CEM III/C{1}, one cover and w/c-ratio within each exposure class

Denmark (DK) XD1, XS1, XS2:CEM I, CEM II/A-L, CEM II/A-LL and

CEM II/A-V

XS3, XD2, XD3:CEM I and CEM II/A-V

One cover and w/c-ratio within each exposure class

Norway (N) XD1, XS1:CEM I, CEM II/A-S, CEM II/B-S, CEM

II/A-D, CEM II/A-V, CEM II/B-V, CEM

III/A

XD2, XD3, XS2, XS3:CEM I + 4 M.% SF/c., CEM II/A-

S, CEM II/B-S, CEM II/A-D, CEM

II/A-V, CEM II/B-V, CEM III/A


United States of America

(USA)

All, except LS or GGBS contents > 70 % (Beushausen & Fernandez, 2011)


Australia (AUS) No recommendations on type of cement and w/c-ratio: durability is verified

with respect to compressive strength combined with cover

{1}Not considered in exposure classes XD2 and XS2


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In the Netherlands traditionally concretes with BFSC are preferred. In Germany preferably CEM II

concretes are used. In Norway concretes with additives like SF of FA are favoured.

Point II: while in P, GB, NL, D, DK and N the exposure classes (European definition: XD and XS)are applied as defined in (EN 1992-1-1, 2002), in AUS, USA and E exposure classes are defined

individually. Especially in AUS the class definition is not identical with the European definition,

which leads to an overlap of the classes. The salinity of oceans is similar with ~35 g/L (except the

Baltic Sea with a salinity of ~8 g/L). Temperature affects the mobility of ions and hence the

diffusion rate, as well as the frequency of usage of de-icing salts. The temperature ranges from

~15C (E and P Southern Europe, AUS), ~10C (GB, NL, D Central Europe, USA) to ~8C

(DK, N Northern Europe) mean annual temperature.

Thus the following countries are considered, see Table 2. Herein, additionally the respective

specifications are summarized.Table 2

Selected countries and specifications taken into accountCountry Considered specifications

Spain (E) EHE-08 (2008)Portugal (P) LNEC E 464 (2007), NP EN 206-1 (2007)

Great Britain (GB) BS 8500-1 (2006), BS 8500-2 (2006), EN 206-1 (2000)The Netherlands (NL) NEN 8005 (2008), EN 206-1 (2000)

Germany (D) DIN 1045-2 (2008), EN 206-1 (2000)Denmark (DK) DS/EN 1992-1-1 DK NA: 2011, DS 2426 (2011), EN 206-1 (2000)

Norway (N) NS-EN 206-1 (2007), NS-EN 1992-1-1 (2008), NS EN 13670 (2010)United States of America (USA) ACI-318-08 (2008)

Australia (AUS) AS 3600 (2009)

In all countries, except USA, deemed-to-satisfy rules are provided for a design service life ofaround 50 years. In some countries additionally rules for a design service life of 100 years are

given. In this publication resistances and reliabilities provided from deemed-to-satisfy rules were

analysed for a design service life of 50 years.

3.2Procedure

Based on Table 1 and Section 2 the following may be concluded.

I. All prescriptive specifications give freedom in choice of cement type. Some prescriptivespecifications give freedom in the choice of combined limiting values (E, P, GB). Hence,

within one exposure class, a concrete composition with a lower resistance (low-resistance

concrete) or a concrete composition with a higher resistance (high-resistance concrete)

may be chosen (Fig. 2).

II. Within one exposure class a high or low chloride load is possible (Fig. 3).Both I. and II. will result in different structural reliabilities (spectrum of reliabilities) within

one exposure class. Therefore, the goal of this work was to determine the spectrum of reliabilities

provided by choosing unfavourable design situations (lower reliability level) and favourable design

situations (upper reliability level). Unfavourable design situations are characterized by a low-

resistance concrete composition (type of cement and w/c-ratio) in combination with a high chloride

load. Favourable design situations are characterized by a high-resistance concrete composition in

combination with a low chloride load.

The procedure to determine the levels of reliability is explained with the example of Germany

exposure class XS3 in detail. The limiting values for the exposure class XS3 as stated in DIN 1045-

2, 2008 are summarized in Table 3.


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Table 3Limiting values (DIN 1045-2, 2008)

Environ-

mental load

Material performance Structural

performanceExposure

class

Minimum cement

content [kg/m]

Minimum

w/c-ratio [-]

Type of cement [-] Nominal concrete

cover cnom= cmin+ c[mm]

XS3 320 0.45 All except CEM II/B-LL, CEM II/B-L,

CEM II/A-W, CEM II/B-W,

CEM IV/A, CEM III/C

55 = 40 + 15

The nominal concrete cover is stated in the specification. The difficulty which arises is the question

as to which type of cement in combination with maximum w/c-ratio yields the low-resistance

concrete or the high-resistance concrete? Which chloride loads in combination should be selected?

Fig. 5 Material performance in dependence of type of cement and w/c-ratio (left), chloride surface

concentration in dependence of the exposure class (right).

In Fig. 5 (left) it can be seen that a low-resistance concrete is provided by CEM II/A-LL. A high-

resistance concrete is provided by CEM III/B, both with a minimum w/c-ratio of 0.45.

In Fig. 5 (right) obviously a high chloride load occurs at a short distance from the chloride

source and a low chloride load further from the chloride source.Based on the above considerations the unfavourable design situation was chosen for a CEM

II/A-LL and a chloride surface concentration of 4.0 wt.%/c. The favourable design situation was

chosen for a CEM III/B and a chloride surface concentration of 2.0 wt.%/c. Both with a w/c-ratio

of 0.45.

All the parameters, which have been described in detail in Section 2 with respect to their

effect on material performance, are listed in in Table 4. In addition to the explanations in Section 2,

all these variables are linked with uncertainties due to the inhomogeneity of material, execution

quality, random temporal and spatial variability of the environmental conditions etc. In order to

take these uncertainties into account each variable was described as a random variable with a

distribution function and its distribution parameters (mean and standard deviation). These

uncertainties were quantified as follows.

Chloride diffusion coefficients are sufficiently described by a normal distribution (Gehlen,2000). The reproducibility is taken into account with a constant coefficient of variation of 0.4.

According to (Gehlen, 2000), the aging exponent may be sufficiently described using a beta

distribution with the boundary conditions 0 < < 1. For saturated conditions (XD2, XD3, XS2,XS3) the standard deviation was set to 0.12, 0.15 and 0.20 for CEM I, CEM II and CEMIII

concretes, respectively. For dry conditions (XD1, XS1) the standard deviation was set to 0.12.

The chloride surface concentration varies randomly due to variations in the chloride content

of the ambient solution, frequency of use of de-icing salts, temporal and spatial variations in the

humidity conditions of the concrete etc. The chloride surface concentration may be sufficiently

described with a lognormal distribution. For urban environments (XD1, XD2 and XD3) a CoV of

75% is documented in DARTS, 2004 because of the huge variability in frequency and amount of

used de-icing salts. For submerged conditions in marine environments (XS2) a low CoV of 25 % is

given which is mainly due to the inhomogeneity of concrete surfaces and the variation in

composition of the ambient solution. With increasing distance to the chloride source (XS3, XS1),

0

1

2

3

4

5

0.4 0.45 0.5 0.55 0.6

Dapp

(t=50)[10-12m

2/s]

w/c-ratio [-]

CEM II/A,B-LL

CEM I

CEM III/A,B

CEM II/A,B-V

CEM II/B-SCEM II/A-D

0

1

2

3

4

5

6

-5 0 5 10 15 20 25

Chloridesurface

concentration[wt.%

/c.]

Distance to chloride source [m]

XS1XS3XS2

< MLT ~ wave crest

favourable

favourableunfavourable

unfavourable


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the random spatial variations increase from a CoV of 45 % (DARTS, 2004) up to 65% (Wall,

2007).

The concrete cover may be sufficiently described with a normal distribution. The mean

concrete cover is the nominal concrete cover a which is the sum of minimal cover and an allowedtolerance. The standard deviation is independent of the mean value and is given by 9 mm (Gehlen,

2000, JCSS, 1999).

Information on the critical chloride content may be found for example in (Breit et al., 2011,

Angst et al., 2009). The critical chloride content may be described by a beta distribution with mean

of 0.6 and a standard deviation of 0.15 with a lower boundary of 0.2 and an upper boundary of 2.0.

The reliability index was calculated according to Eq. 3, where the depth with a critical chloride

content (C = Ccrit) is compared with the concrete cover a. Both are described as random variables

(Ditlevsen & Madsen, 2005).

( ) { } ( )00crit.dep pa)t,C(xpp


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Fig. 6 Reliability index versus design service life for the unfavourable and the favourable design situation.

Reliability spectrum provided when following the recommendations of deemed-to-satisfy rules of German

specification for XS3.

3.3Reliability spectra

This methodological approach was applied for each country and exposure class.

In Fig. 7 a and b (left) the w/c-ratio and the concrete cover is given for each country and

exposure class. Additionally, the favourable and unfavourable types of cement are stated which

may be selected when taking into consideration the permitted types of cement of Table 1. In Fig. 7

a and b (right) the reliability spectrum (bars) derived from the unfavourable and favourable design

situation at the end of design service life (50 years) is shown for each country and exposure class.

Fig. 7a Favourable and unfavourable type of cement, maximum w/c-ratio and minimum cover (left),

reliability spectra (right).

-2

-1

0

1

2

3

4

0 10 20 30 40 50

Reliabilityindex

[-]

Time t [a]

CEM III/B

favourable

CEM Iunfavourable

reliabilityspectrum

-2

-1

0

1

2

3

4

-2

-1

0

1

2

3

4

-2

-1

0

1

2

3

4

0.3

0.4

0.5

0.6

0.7203040506070

0.30.4

0.5

0.6

0.72030405060700.3

0.4

0.5

0.6

0.7

2030

40506070

XD1

XD2

XD3

E P GB NL D DK N USA AUS

Reliability index [-]

w/c-ratio[-]

cmin[mm]

w/c-ratio[-]

cmin[mm]

w/c-ratio[-]

cmin[mm]


CEMIII

CEMI

w/c = 0.45

w/c = 0.60

CEMI

CEM III

favourable CEM III/B, II/A-V

unfavourable CEM I, II/A-LL

favourable CEM III/B, II/A,B-V

unfavourable CEM I , II/A-LL


unfavourable CEM I, II/A-LL, II/A-S

CEMIII

CEMI

w/c = 0.4

w/c = 0.55

CEMI

CEM III

CEMIII

CEMI

w/c = 0.35

w/c = 0.5CEMI

CEM III


11/20

Fig. 7b Favourable and unfavourable type of cement, maximum w/c-ratio and minimum cover (left),

reliability spectra (right), AUS: w/b ratios appraised from concrete strength requirements, exposure class C1was assumed to be equivalent to XS1, USA: concrete cover in dependency to bar diameter, cover tabled

refers to bars of diameter ds> 19 mmThe lower reliability level (bottom of bars) results when selecting CEM I, CEM II/A-LL,

CEM II/A-S cements. The upper reliability level (top of bars) results when selecting CEM III or

CEM II/A,B-V cements.

In all exposure classes, an increased cover (E) for low-resistance types of cements or the

exclusion of low-resistance types of cement (N) leads to a narrower reliability spectrum. The same

holds for a reduced w/c-ratio (P) for low-resistance types of cement, but with less effect. An

increase in w/c-ratio of about 0.1 in combination with an increase of cover of about 10 mm yields

no significant change in reliability spread (GB).

The above reliability spectra were calculated with the listed data in Section 2. These

calculations were subject to simplifications and effects that, strictly, are not taken into properconsideration. Some effects and simplifications are due to:

-the variety of specific surface effects ,-neglecting the effect of discrete changes in diffusion coefficient during the design service life,-neglecting the time-dependent development of chloride surface concentration in the first five

to ten years of exposure (Bioubakhsh, 2011, Markeset & Skjlsvold, 2010)

-neglecting the effect of binding on the concentration gradient (Baroghel-Bouny et al., 2012)In order to quantify the effect of these simplifications, the reliabilities of some existing structures

where checked.

0.3

0.4

0.50.6

0.7

2030405060700.3

0.40.5

0.6

0.7

203040506070

0.3

0.4

0.5

0.6

0.7203040506070

-2

-1

0

1

2

3

4

-2

-1

0

1

2

3

4

-2

-1

0

1

23

4XS1

XS2

XS3


Reliability index [-]

w/c-ratio[-]

cmin[mm]

w/c-ra

tio[-]

cmin[mm]

w/c-ratio[-]

cmin[mm]


CEMIII

CEMI

w/c = 0.35

w/c = 0.55CEMI

CEM III

favourable CEM III/B, II/A-V

unfavourable CEM I , II/A-LL


unfavourable CEM I, II/A-LL


unfavourable CEM I, II/A-LL, II/A-S

CEMIII

CEMI

w/c = 0.4

w/c = 0.55CEMI

CEM III

CEMIII

CEMI

w/c = 0.35

w/c = 0.5

CEMI

CEM III


12/20

3.4 Verification by assessing existing structures

By assessing existing structures, the in-field performance of the material was determined. In-field

performance is given by measured chloride profiles and is used to

- analyse whether the predicted chloride concentrations reflect the real behaviour.- verify the reliability spectra determined by reliability design with field reliability.

MethodologyIn order to verify the model predictions all measured chloride profiles for individual structures

where compared with the predicted performance represented by the calculated chloride profiles.

Chloride contents were calculated for the specific design situation using Ficks second law (Eq.

(2)). The model parameters where varied randomly in a Monte Carlo approach to yield chloride

concentration distributions (50 % and 95% quantiles) at discrete depths (Ditlevsen & Madsen,

2005).

In order to verify the calculated reliability spectra in Figs. 7, the measured depth-dependent

chloride contents where used to calculate the reliability at the end of design service life within a

Bayesian update as is well-documented in (Ditlevsen & Madsen, 2005). This requires that the

material composition on-site fulfils the requirements stated in the specifications.

Field investigations

Chloride profiles from structures older than 5 years where provided by the members of fib-TG5.11. In Table 5 the age of the investigated structural elements, the country, the related exposure

class, the description of the location, the concrete composition (w/c-ratio and type of cement) as

well as the cover required by the specific specification are summarized.Table 5

On-site investigations fromfib-TG 5.11

No. age[a]

Coun-try

Exposureclass

Description of location Type of cement w/c-ratio[-]

cmin[mm]

1 5 P XS3 Setenave shipyards, Atlantic Ocean CEM I + 5 % SF 0.35 45

2 18 NL XS3 Box girder bridge wall, North Sea CEM III/B 0.45 40

3 6 D XS2 Specimens exposed to Eckenfrde, Baltic

Sea (exposed specimen)

CEM I 0.47 40

4 6 XS2 CEM III/A 0.47 40

5 6 XS3 Specimen exposed to wall of Eider barrage,

North Sea (exposed specimen)

CEM I 0.45 40

6 6 XS3 CEM III/A 0.45 40

7 30, 40 XS3 Wall of Eider barrage, North Sea

(Osterminski & Gehlen, 2009)

CEM I + 5 % trass 0.45 40

8 12 DK XS3 Bridge pile CEM I + FA 0.38 35

9 32 XS3 Bridge pile CEM I 0.40 35

10 8 N XS2 Floating structure Troll B

(Helland et al., 2010)

CEM I +7 % SF 0.35 50

11 5, 9 XS3 Floating structure Heidrun

(Helland et al., 2010)

CEM I + 5 % SF 0.39 50


13/20

Fig. 8 shows some of the locations.

Fig. 8 Some of the locations investigated by fib-TG 5.11 (www.somague.pt, www.shz.de, www.

eiderstedt.net, Helland et al., 2010).

ResultsIn Figs. 9 (left) the measured chloride profiles from each field investigation are compared with the

calculated chloride profiles. In Figs. 9 (right) the evolution of the reliability indices is shown as

determined by reliability designs presented in Section 3.2 and 3.3. Furthermore, the field

reliabilities are given. Here the field reliabilities are based on the measured chloride profiles and

the concrete cover required by the standards.

Fig. 9a Measured chloride concentrations and calculated chloride concentrations (left), reliability index

versus time determined by reliability design and by assessing existing structures (right) Southern Europe.


14/20

Fig. 9b Measured chloride concentrations and calculated chloride concentrations (left), reliability index

versus time determined by reliability design and by assessing existing structures (right) Central Europe.

0

2

4

6

0 10 20 30 40 50 60 70 80

tinsp = 40 years

-2

-1

0

1

2

3

4

0 10 20 30 40 50

Reliabilityindexb[-]

2

4

6No. 7

tinsp = 30 years

-2

-1

0

1

2

3

4

0

1

2

3

4

5

6No.6

-2

-1

0

1

2

3

4

Reliability

index

[-]

0

1

2

3

4

5

6No.2

-2

-1

0

1

2

3

4

Reliabilityindex

[-]

0

1

2

3

4

5

6No.3

-2

-1

0

12

3

4

Reliabilityindex

[-]

0

1

2

34

5

6No.4

-2

-1

0

1

2

3

4

Reliabilityindexb[-]

0

1

2

3

4

5

6No.5

Chloridecontent[wt.%/c.]

Reliabilityindex

[-]

Depth x [mm] Time t [a]


15/20

Fig. 9c Measured chloride concentrations and calculated chloride concentrations (left), reliability index

versus time determined by reliability design and by assessing existing structures (right) Northern Europe.

In Figs. 9 it can be seen that the measured chloride profiles agree very well with the calculated

chloride profiles. Furthermore, the field reliabilities are mostly higher than the ones determined by

reliability design (No. 1, 2, 3, 4, 5, 6, 7, 10, 11). The field reliability is only lower for No. 8 and 9,

where high chloride contents where measured. For structure No. 8, the performance of FA was

overestimated because no information about the actual FA content existed. In the case of No. 10 the

performance of SF was underestimated.

3.5 Comparison and discussion

In Fig. 10 the reliability spectra determined by the reliability design shown in Figs 8 (right) is

reproduced. Here, the field reliabilities are added using symbols. The ranges of all reliabilities are

marked by the grey beams.

-2

-1

0

1

2

3

4

0 10 20 30 40 50

0

2

4

6

0 10 20 30 40 50 60 70 80

tinsp = 9 years

2

4

6No.11

tinsp = 5 years

-2

-1

0

1

2

3

4

0

1

2

3

4

5

6No.9

Chloridecontent[wt.%/c.]

Reliabilityindex

[-]

-2

-1

0

1

2

3

4

0

1

2

3

4

5

6No.10

Depth x [mm]

-2

-1

0

1

2

3

4

0

1

2

3

4

5

6No.8

Time t [a]


16/20

Fig. 10 Spectra of reliabilities provided by deemed-to-satisfy rules for a design service life of 50 years

determined by reliability design (bars) and by assessing existing structures (symbols).In Fig. 10 it can be seen that the reliability spectrum is always broad, independent of the exposure

class. The lower reliability level determined when selecting low-resistance types of cements is

confirmed by the field investigations (CEM I). The same holds for the upper reliability level

determined when selecting high-resistance types of cement (CEM III, CEM II/A-D). Therefore, it

can be concluded that the wide spread of reliability within each exposure class results from the

huge differences in material performance.

In Fig. 10 it can be seen that the reliability level (grey beams) is systematically higher for the

exposure classes XD1 and XS1 and systematically lower for the exposure classes XD2, XD3, XS2,

XS3. The lowest reliability level (bottom bar) for the exposure classes XD1 and XS1 is = 1.5, for

the exposure classes XD2, XD3 and XS2is -1.0 and for the exposure class XS3is -1.5.

In current standards and supplementary documents a variety of reliability levels 0 areproposed for durability limit states for example:

0= 0.5 (Gehlen et al., 2008, DAfStb, 2008, Zilch & Schiel, 2001), 0= 0.8 (Teply & Novak,

2012), 0= 1.0 (Sarja, 2005), 0= 1.2 (LNEC E 465, 2007), 0= 1.3 (fib, 2006, Gulvanessian et

al., 2002, JCSS, 2000), 0= 1.5 (EN 1990, 2002), 0= 1.7 (JCSS, 2000), 0= 1.8 (NEN 6700,

2005), 0= 2.0 (LNEC E 465, 2007, Zilch & Schiel, 2001) and 0= 2.3 (Sarja, 2005,Gulvanessian et al., 2002, JCSS, 2000). Except for the exposure classes XD1 and XS1, the

reliability level provided by deemed-to-satisfy rules is, at least for unfavourable design situations,

below all the proposed target reliabilities.

Therefore it can be concluded that the major consequences of the current prescriptive approach are:

- lack of safety for specific design situations,- lack of economic viability of prescriptive designed structures.This results mainly from the lack of reliable information on the durability properties of the concrete

(type of cement) which makes it difficult to evaluate concrete quality and performance in the

respective environmental load. In order to overcome the current problems an adaption of deemed-

to-satisfy rules is required, where the limiting values are derived from scientifically verified

material resistances (performance based deemed-to-satisfy rules). Therefore, a system with

exposure resistance classes is proposed (Leivestad, 2013).

4 Proposal for performance based deemed-to-satisfy rules

The methodological approach for ensuring durability based on exposure resistance classes inanalogy to the approach for ensuring load-bearing capacity based on strength classes is shown in

Fig. 11.

-2

-1

0

1

2

3

4

-2

-1

0

1

2

3

4

XD1 XD2 XD3

XS1 XS2 XS3

Reliabilityindex

[-]Reliabilityindex

[-]

E P GB NL D DK N USA AUS E P GB NL D DK N USA AUS E P GB NL D DK N USA AUS

CEM I

CEM IIICEM III

CEM IIISF

SFSF

CEM I


17/20

Fig. 11 Methodological approach for ensuring durability based on exposure resistance classes in comparison

with the approach for ensuring load-bearing capacity based on strength classes (RSD for Exposure Resistance

Class Sea/De-Icing Salts, RC for Exposure Resistance Class Carbonation).Exposure resistance classes classify concrete performance. Compliance of a specific concrete

composition with the exposure resistance class is tested under standard conditions using a certain

test specification. The class definition gives the characteristic material performance and the

environmental action. For example the exposure-resistance class RSD45 stands for a characteristic

chloride ingress depth (depassivation will occur with a probability of 10%) of 45 mm (chloride

resistance class). Based on the characteristic material performance the cover required to withstand

the specific environmental load (exposure class) is derived from (reliability) design. This approach

is comparable with the approach for ensuring load-bearing capacity based on strength classes.

Here, material performance is classified and characterized by strength classes. Compliance is tested

under standard conditions. The dimensions of the structural component required to withstand the

actual load are derived from (reliability) design based on the characteristic strength of the concrete.

In order to maintain the prescriptive concept deemed-to-satisfy rules have to be determined.

Deemed-to-satisfy rules have to be laid down for the concrete composition parameters (w/c-ratio,

type of cement etc.) for which a reliable relationship with the relevant material performance

(exposure resistance, e.g. chloride ingress depth) is documented. For the relevant material

performance, the different cover required to withstand the conditions of the individual exposure

classes may be given in design tables for a specified design service life. Thus, for common design

situations, no reliability design is to be performed. For the carbonation resistance classes (RC),

deemed-to-satisfy values have been developed and introduced in (Greve-Dierfeld & Gehlen, 2014).

Those rules are also based on a benchmark for deemed-to-satisfy rules performed for the exposure

classes XC1, XC2, XC3 and XC4 (Gehlen & Greve-Dierfeld, 2013).

The advantage of this new approach is that reliable information on the durability properties of theconcrete composition is available. This results in (see Fig. 12)

- an increased safety margin for specific design situations and- an improved economic viability of the structures.

Fig. 12 Reliability spectra provided by current deemed-to-satisfy rules (left), reliability spectra provided

when specifying cover in dependence of exposure resistance class (right).

-2

-1

0

1

2

3

4

-2

-1

0

1

2

3

4

Reliabilityindex

[-]

XS3


Reliabilityindex

[-]

XS3



18/20

Acknowledgement

The authors wish to acknowledge the assistance and support of thefib-TG 5.11.

References

ACI-318-08 (2008), Building code requirements for structural concrete. American Concrete

Institute, United States of America.

Angst, U., Elsener, B., Larsen, C., Vennesland, O. (2009), Critical chloride content in reinforced

concrete a review. Cement and Concrete Research 39, pp. 1122-1138.

AS 3600 (2009), Concrete structures. Standards Australia GPO Box 476, Sydney, NSW 2001,

Australia.

Baroghel-Bouny, V. Wang, X., Thiery, M., Saillio, M., Barberon, F. (2012), Prediction of chloride

binding isotherms of cementitious materials by analytical model or numerical inverse

analysis. Cement and Concrete Research, Vol. 42, pp. 1207-1224.

Beushausen, H., Fernandez, L. (2011), Performance based specification and control of concrete

durability. WG3 State-of-the-Art report on prescriptive durability specifications.

Bioubakhsh, S. (2011), The penetration of chloride in concrete subject to wetting and drying:

Measurement and modelling. Ph.D. thesis, UCL University College London, Great Britain.

Bjegovic, D., Stirner, N., Serder, M. (2012), Durability properties of blended cement concrete.

Materials and Corrosion, Vol. 63, Issue 12, pp. 1087-1096.

Breit, W., Dauberschmidt, C., Gehlen, Ch., Sodeikat, C., Taffe, A., Wiens, U. (2011), Zum Ansatz

eines kritischen Chloridgehalts bei Stahlbetonbauwerken. Beton- und Stahlbetonbau, Vol.

106, Issue 5, pp. 290-298.

BS 8500-1 (2006), Concrete complementary British Standard to BS EN 206-1 Part 1: Method

of specifying and guidance for the specifier. London, Great Britain.

BS 8500-2 (2006), Concrete complementary British Standard to BS EN 206-1 Part 2:Specification for constituent materials and concrete. London, Great Britain.

Caballero, J., Polder, R.B., Leegwater, G., Fraaij, A. (2010), Chloride penetration into cementitious

mortar at early ages. 2nd International Symposium on Service Life Design for Infrastructure,

October 2010, Deft, The Netherlands.

Chrisholm, D.H., Lee, N.P. (2001), Actual and effective diffusion coefficients of concrete under

marine exposure conditions. 20thBiennial Conference of the Concrete Institute of Australia,

Perth, Australia.

DAfStb (2008), Positionspapier zur Umsetzung des Konzepts von leistungsbezogenen

Entwurfsverfahren unter Bercksichtigung von DIN EN 206-1, Anhang J. Beton- und

Stahlbetonbau, Vol. 103, Issue 12, pp. 837-839.

DARTS (2004), Durable and reliable tunnel structures DATA. Project with financial support of

the European Commission under the Fifth Framework Program, GROWTH 2000 ProjectGRD1-25633, Contract G1RD-CT-2000-00467.

DD CEN/TS 12390-11 (2010), Testing hardened concrete Part 11: Determination of the chloride

resistance of concrete, unidirectional diffusion.

DIN 1045-2 (2008): Tragwerke aus Beton, Stahlbeton und Spannbeton - Teil 2: Beton - Festlegung,

Eigenschaften, Herstellung und Konformitt - Anwendungsregeln zu DIN EN 206-1.

Ditlevsen, O., Madsen, H.O. (2005), Structural reliability methods. Coastal, maritime and structural

engineering, department of mechanical engineering, Technical University of Denmark, ISBN

0 471 96086 1.

DS 2426 (2011), Concrete materials rules for application of EN 206-1 in Denmark. Danish

Standards Association, Charlottenlund, Denmark.

DS/EN 1992-1-1 DK NA: 2011: National Annex to Eurocode 2: Design of concrete structures

Part 1-1: General rules and rules for buildings.EHE-08 (2008), Code on structural concrete. Ministerio de Fomento, Spain.


19/20

EN 1990 (2002), Eurocode - basis of structural design.

EN 1992-1-1 (2002), Eurocode 2: design of concrete structures - Part 1: General rules and rules for

buildings.

EN 206-1 (2001), Concrete - Part 1: Specification, performance, production and conformity.fib(2006), Model code for service life design. Bulletin of thefib. Lausanne, Switzerland.Fluge, F., Helland, S., Maage, M., Smeplass, S. (2001), Marine chlorides a probabilistic approach

to derive durability related provisions for NS-EN 206-1. Report No. 19 / BP1 B4 of the R&D

project Betongkonstruksjoners liveslop, Oslo, Norway.

Gehlen, Ch. (2000), Probabilistische Lebensdauerbemessung von Stahlbetonbauwerken-

Zuverlssigkeitsbetrachtung zur wirksamen Vermeidung von Bewehrungskorrosion.

Doctoral thesis, RWTH Aachen, Germany.

Gehlen, Ch., Schiel, P., Schiel-Pecka, A. (2008), Hintergrundinformationen zum Positionspapier

des DAfStb zur Umsetzung des Konzepts von leistungsbezogenen Entwurfsverfahren unter

Bercksichtigung von DIN EN 206-1, Anhang J, fr dauerhaftigkeitsrelevante

Problemstellungen. Beton- und Stahlbetonbau, Vol. 103, Issue 12, pp. 840-851.

Gehlen, Ch., Greve-Dierfeld, S. von (2013), Lebensdauer von Stahlbetonbauteilen - Empfehlungenfr eine modifizierte deskriptive Bemessung. Band 1, Kapitel III. In: Konrad Bergmeister,

Frank Fingerloos, Johann-Dietrich Wrner (Hrsg.): Beton-Kalender 2013. Ernst & Sohn

GmbH & Co. KG, pp. 223-270.

Ghods, P., Chini, R., Alizadeh, M., Hoseini, M., Shekrachi, A.A., Ramezanianpour (2005): The

effect of different exposure conditions on the chloride diffusion into concrete in the Persian

Gulf region. ConMAT Conference. Vancouver, Canada.

Greve-Dierfeld, S. von, Gehlen, Ch. (2014), Performance based deemed-to-satisfy rules.

Proceeding of the fourth International fib congress 2014 - Improving performance of concrete

structures, February 2014, Mumbai, India.

Gruyaert, E., Van den Heede Ph., De Belie, N. (2009): Chloride ingress for concrete containing

blast-furnace slag related to microstructural parameters. RILEM Workshop on Concrete

durability and service life planning, Concrete life 09, Haifa, Israel.Gulvanessian, H., Calgaro, J-A., Holicky, M. (2002), Designers guide to EN 1990 Eurocode: basis

of structural design. Thomas Telford Ltd., London, Great Britain, ISBN: 0 7277 3011 8.

Heinz, D., Urbonas, L., Gbel, M., Schubert, J. (2011), Praxisgerechte flugaschereiche Betone mit

Hochleistungsfliemittel. BetonWerk International, Vol. 51, pp. 36-45.

Helland, S. Aarstein, R., Magne, M. (2010), In-field performance of North Sea offshore platforms

with regard to chloride resistance. Structural Concrete, Vol. 11, Issue 2.

ISO 16204 (2012), Durability Service life design of concrete structures. ISO FDIS 16204:

updated 2012-08-08, ISO TC 71/SC 3.

JCSS (1999), JCSS probabilistic model code Part 3: Resistance models. Joint committee on

structural safety.

JCSS (2000), JCSS probabilistic model code Part 1: Basis of design. Joint Committee on Structural

Safety.

Lay, S., Schiel, P. (2002), Dauerhaftigkeitsbemessung von Stahlbetonkonstruktionen.

Forschungsbericht AiF/DBV-Nr. 12525/225, Technical University Muenchen, Germany.

Leivestad, S. (2013), Durability exposure resistance classes, a new system to specify durability in

EN 206 and EN 1992. Memo durability classes, JWG 250/104 N19C.

LNEC E 464 (2007), Betoes metodologia prescritiva para uma vida util de projecto de 50 e de 100

e face as accoes ambientais. Laboratorio naional de engenharia civil, Portugal.

LNEC E 465 (2007), Concrete - methodology for estimating the concrete performance properties

allowing to comply with the design working life of reinforced or pre-stressed concrete

structures under environmental exposures XC and XS. MOPTC - Laboratrio Nacional de

Engenharia Civil, Portugal.

Markeset, G., Skjlsvold, O. (2010), Time dependent chloride diffusion coefficient field studiesof concrete exposed to marine environment in Norway. 2nd International Symposium on

Service Life Design for Infrastructure, October 2010, Deft, The Netherlands.


20/20

Mller, Ch., Severins, K. (2009), Durability of concretes made with cements containing fly ash.

Concrete Technology Reports 2007-2009.

Mller, Ch., Severins, K., Hauer, B. (2009), New finding concerning the performance of cements

containing limestone, granulated blast-furnace slag and fly ash as main constituents.Concrete Technology Reports 2007-2009.

NEN 6700 (2005), Technical principles for building structures. The Netherlands.

NEN 8005 (2008), Dutch supplement to NEN-EN 206-1: Concrete - part 1: specification,

performance, production and conformity. The Netherlands.

Nokken, M., Boddy, A., Hooton, R.D., Thomas, M.D.A. (2006), Time dependent diffusion in

concrete three laboratory studies. Cement and Concrete Research, Vol. 36, pp. 200-207.

NP EN 206-1 (2007), Beto Parte 1: Especificao, desempenho, produo e conformidade. IPQ,

Lisboa, Portugal.

NS EN 13670 (2010), Utfrelse av betongkonstruksjoner. Norway.

NS-EN 1992-1-1 (2008), National annex to EN 1992-1-1. Norway.

NS-EN 206-1 (2007), National annex to EN 206-1. Norway.

NT BUILD 443 (1995), Nordtest method - concrete, hardened: accelerated chloride penetration.NT BUILD 492 (1999), Nordtest method - concrete, mortar and cement-based repair materials:

chloride migration coefficient from non-steady-state migration experiment.

Osterminski, K., Gehlen, Ch. (2009), Zuverlssigkeit Wasserbauwerke Chlorideindring-

widerstand. Forschungsbericht 30-F-0019, TU Muenchen, Germany.

Polder, R.B., Wegen, G. van der, Breugel, K. van (2010), Guideline for service life design of

structural concrete with regard to chloride induced corrosion The approach in the

Netherlands. 2nd International Symposium on Service Life Design for Infrastructure,

October 2010, Deft, The Netherlands.

Sarja, A. (2005), Generic limit state design of structures. 10DBMC International Conference on

Durability of Building Materials and Components, 17-20 April 2005, Lyon, France.

Stanish, K., Thomas, M., (2003), The use of bulk diffusion tests to establish time-dependent

concrete. Cement and Concrete Research, Vol. 33, pp. 5562.Tang, L., Utgenannt, P., Lindvall, A., Boubitsas, D. (2010), Validation of models and test methods

for assessment of durability of concrete structures in road environment. Uppdragsrapport No.

P802606, Lund, Sweden.

Tang, L. (1996), Chloride transport in concrete measurement and prediction. Ph.D. thesis,

Chalmers University of Technology, Gothenburg, Denmark.

Teply, B., Novak, D. (2012), Limit states of concrete structures subjected to environmental actions.

18th International Conference on Engineering Mechanics, 14-17 May 2012, Prague, Czech

Republic.

Visser, J.H.M., Nijland, T.G. (2009), Performance of tenary OPC-FGGBS-FA binder in meeting

conflicting concrete durability demands. IBAUSIL, Weimar, Germany.

Wall, H. (2007), Chloride profiling in marine concrete methods and tools for sampling. Ph.D.

thesis, Lund Institute of Technology, Sweden.

Wiens, U. (2005), Zur Wirkung von Steinkohleflugasche auf die chloridinduzierte Korrosion von

Stahl in Beton. Doctoral thesis, RWTH Aachen, Germany.

Zilch, K., Schiel, A. (2001), The determination of the nominal concrete cover by durability

design. Background document to Chapter 4 in EN 1992-1-1, February 2001.

benchmark for deemed-to-satisfy rules xd

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