influence of concrete composition on the …third rilem workshop on testing and modelling the...

INFLUENCE OF CONCRETE COMPOSITION ON THE TRANSPORT OF CHLORIDE IONS IN CONCRETE M. Manuela Salta and A. B. Ribeiro Laboratório Nacional de Engenharia Civil – Lisboa – Portugal Abstract The influence of concrete composition on the ingress of chloride ions under marine atmosphere, submerged and splash seawater environments has been evaluated for eight concrete mixtures. Characterisation of concrete mixtures has been made at 28 days of age involving performance properties related with the resistance to chloride ingress: resistivity, charge transported under an electrical field, capillary absorption and chloride diffusion coefficients in non-steady-state accelerated (diffusion or migration) conditions. Concrete specimens have been exposed in marine environments and chloride ingress has been measured after 6 months of exposure. This paper correlates the results from concrete performance properties measured at 28 days with composition parameters (W/C ratio, cement content and compressive strength) and with the achieved chloride diffusion coefficients of concrete mixtures estimated after 6 months of natural exposure using an analytical solution of Fick´s 2nd law of diffusion. 1. Introduction Corrosion of the steel reinforcement in concrete caused by chloride ingress is a major durability problem for reinforced concrete structures in marine environments. According to FIP/CEB Model Code and European Standards for reinforced concrete, the designer of reinforced concrete structures must to verify that structures withstand a number of “limit states”. This verification is based on a probabilistic approach using characteristic numbers for the action and the material resistance to the different actions. Due to the lack of reliable models no characteristic parameters are already defined for the verification of the limit states involving aggressive environmental actions. Designers

(c) 2005 RILEM, Bagneux, France

Third RILEM workshop on Testing and Modelling the Chloride Ingress into Concrete9-10 September 2002, Madrid, Spain

use “rules-of-thumb” which link the class of environmental aggressiveness to a required concrete composition, from the indications given in some concrete standards. The European Standard EN 206-1 (1), recommends applicable requirements in terms of limiting values for concrete composition, for concrete withstanding environmental actions. On the assumption of an intended service lifetime of 50 years, for each exposure class, these requirements refer to: type and class of constituent materials; maximum W/C; minimum cement content; minimum concrete compressive strength class (optional); minimum air-content of the concrete (if relevant). However, the European Standard (in Annex F) gives recommendations for choosing some of the limiting values only in very restrictive conditions, when using portland cement, CEMI conforming to EN 197-1 (2), and aggregates with maximum nominal upper size in the range of 20 mm to 32 mm. The use of this prescriptive method based only on the concrete composition for new structures or repaired structures instead of the adoption of safety design rules directly related with concrete durability may be, in some cases, the main cause of the increased number of new structures showing reduced service life for some new structures. In other cases, excessively restrictive concrete composition requirements are defined in relation to the intensity of the environmental action, thus increasing costs of construction. Some reasons for the lack of reliable models on environmental aggressiveness include: 1) the transport of chloride ions in concrete is not a simple diffusion process, it is affected by a number of factors partly related to the characteristics of the concrete and partly to the characteristics of the exposure environment; 2) chloride ingress in concrete can not be described only by the diffusion laws; 3) no agreement has been yet reached on reference methods to test chloride penetration in concrete and 4) very little field performance data reported about the correlation between the concrete performance properties and the durability of different concrete mixtures according to the class of aggressiveness of the natural exposure conditions. Recently, a research program has been initiated, which has the main objectives:

• to evaluate the relevance of different performance tests to the concrete characterisation related to durability;

• to analyse the correlation between concrete performance properties with in-situ behaviour to achieve their limit values reported to the different classes of exposure.

Eight concrete mixtures have been prepared, including cement type I 32.5 R and IV 32.5 in different contents from 260 to 530 kg/m3 and w/c ratios from 0.30 to 0.65. Silica fume has also been used in the concrete mixes with the highest cement content and the lowest w/c ratio. Some of the mixtures with cement type I respect the limit values established by the EN 206-1 for the three classes of marine environment. Concrete specimens with



and without reinforcements have been prepared for concrete characterisation at 28 days and for natural exposure. As the chloride ingress on concrete depends on the environmental aggressiveness and the characteristics of the concrete, the main physical and chemical processes in concrete expected to give the largest contribution to chloride transport in concrete are water and moisture transport, ionic diffusion, and chemical reactions between chloride ions and the cement paste. Based in these assumptions, in this study some performance properties related to some of these processes have been selected for the characterisation of the eight concrete mixtures at 28 days. These include: resistivity and electrical charge transported under an electrical field according to the ASTM C 1202 test method (3), capillary absorption, and chloride diffusion coefficients performed under accelerated non-steady-state conditions. To evaluate the environment factors three marine exposure conditions have been selected at the Atlantic coast around 30 km to the north of Lisbon, in: seawater airborne salt zone, tidal zone, and permanently immersed in the seawater. Two reinforced concrete and two plain concrete prisms from all the eight concrete mixtures were exposed in each of three conditions. Five years is the estimated duration for the natural exposure tests. Chloride profiles have been measured on concrete prisms at 6 months of exposure. Periodic electrochemical measurements have been also performed on the reinforced concrete prisms to detect ecorrosion initiation in the different exposure conditions, but their results are not analysed in this paper. This paper evaluates the relevance of the different performance properties, for the characterization of concrete compositions, as well as the correlations between these properties and the achieved chloride transport coefficients in concrete, estimated from the chloride profiles measured after 6 months of exposure. Some considerations are also made concerning the test methods to measure the performance properties. 2. Experimental Part 2.1. Materials Eight concrete mixtures have been prepared using two types of cement: a portland cement CEM I 32.5 R and a pozzolanic cement CEM IV/B 32.5, in accordance with EN 197-1. Limestone coarse aggregates and natural silica sand have been used. Concrete mixtures included three water reducing admixtures: Pozzolith 390 N, based on modified lignosulphonates; Rheobuild 1000, based on polynaphthalene sulphonated condensate; and Glenium 27, based on polycarboxilic acid. Silica fume has also been used in some mixtures. Tables 1-3 show the properties of the cements and aggregates used. Table 4 presents the proportions of the eight concrete mixtures. This table also indicates the slump value, the W/C and the 28 day compressive strength on 150 mm cubic



specimens. Table 5 shows the limiting values for concrete composition, based in Annex F of EN 206-1, for the three exposure classes related to corrosion induced by chlorides studied in this work. 2.2. Laboratory tests at 28 days For each mixture, different tests on laboratory specimens have been carried out to determine concrete performance properties that are expected to be more related with corrosion degradation processes of concrete due to the influence of chloride ions. The properties evaluated have been: concrete resistivity, electrical charge transported in concrete according to the ASTM C 1202 test method, chloride diffusion coefficients obtained in non-steady state under diffusion or migration conditions, and capillary absorption. Different types of specimens have been prepared according to the test procedures. After casting concrete specimens have been removed from the moulds at 24 hours, stored for 7 days in a moist curing room (20±2ºC and >95% RH) and then, generally, maintained in closed plastic bags at the laboratory (21±3ºC and 60±5% RH) until 28 days. From the values measured for each property, the mean values and the standard deviation have been calculated for each concrete mixture. 2.2.1. ASTM C1202 electrical charge transported and resistivity The electrical charge transported in concrete has been measured on three 50 mm thick test slices, cut from the middle of concrete cylinder specimens with 100 mm diameter and 200 mm height and prepared according the test method ASTM C 1202 (3). After vacuum water saturation, the resistivity of concrete has been measured at 1000 Hz with ac impedance equipment, using two stainless steel electrodes contacting the concrete plane surfaces through moist pads. Specimens were then installed in the cell, the electrical field of 60 Vdc applied over 6 hours, and the charge transported during this time was calculated (3). When the test has been concluded, concrete specimens were cracked in two halves along the thickness by compression and the chloride penetration front measured by a colorimetric test using an 0.1 M AgNO3 aqueous solution, applied to the fresh concrete broken surfaces (4). 2.2.2. Chloride diffusion coefficient in non-steady state conditions Concrete cylinders with 100 mm diameter and 200 mm height, as well as 150 mm cubes have been cast. Chloride diffusion coefficients in non-steady-state conditions have been calculated following three test methods, two under migration (methods A and B) and one under chloride diffusion from a NaCl solution with a high concentration (method C). Method A - Migration test using the colorimetric front measured after ASTM C1202 test From the colorimetric chloride front depth, measured after ASTM 1202 test and using equation [1], proposed by C. Andrade, the chloride diffusion coefficient in non-steady- state migration conditions (Dns) has been estimated for the different mixtures.



⎥⎦⎤

⎢⎣⎡ −= 2

2coth

tL102Dns 2

2 νννcx [1]

Where, L is the thickness of concrete specimen, t is the test duration, xc the colorimetric chloride front and ν= ze∆φ/kT, with z the ionic valence, e the electron charge, ∆φ the potential, k the Boltzman constant, and T the absolute temperature . Method B - Migration test by NT Build 492 standard For each concrete mixture three concrete slices with 50 mm thickness cut from the middle of the 100 mm of diameter by 200 mm of height concrete cylinders have been tested following the NT Build 492 (5) standard, at the temperature of 23±2ºC. Chloride diffusion coefficients have been estimated using the solution of the Nernst – Planck equation given by equation [2].

t

xx

zFERTDns dd α−

= [2]

Where, ⎟⎠⎞

⎜⎝⎛ −⋅

Δ=α

−

CoCd21erf

EzFRTL2 1 , with z- chloride ion valence , F- Faraday

constant, E=(U-2)/L and U – potential applied, L – thickness of concrete specimen, R-real gas constant, T- temperature, xd – chloride penetration depth, Cd –the chloride content sensible to change the colour , Co – chloride content on the catholyte solution and t – test duration. Method C – Ponding test by NT BUILD 443 standard The ponding test has been performed at the temperature of 23±2ºC using the general procedure of NT BUILD 443 (6) with 165±1 g/L NaCl solution and test duration of 2 and 4 months. From each concrete mixture two cylinders with 100mm of diameter and height have been tested. After to 2 or 4 months of immersion, powder concrete samples have been obtained from the concrete specimens, by drilling at increments of 2 mm in the first 20 mm and, after that, at increments of 5 mm. Samples have been analysed for total chloride ions using a chloride selective electrode. The effective chloride transport coefficient (Dns) has been estimated by fitting of chloride profiles to the solution of 2nd Fick´Law equation given by [3],



( )⎥⎥

⎦

⎤

⎢⎢

⎣

⎡

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛−−=

tD2x erf -1CCCt)C(x,

nsiss

[3]

Where: Cs is the chloride content at the concrete surface, Ci is the initial chloride content in concrete, C(x,t) is the chloride content at the x depth and time t, x is the penetration depth from the concrete surface. 2.2.3. Capillary absorption Capillary absorption have been performed on concrete slices with (150mm of diameter and 50 mm of height). Three slices from each mixture have been cut from the inner part of standard cylindrical specimens with 300 mm height, after the 7 days of moist curing. The concrete slices have been placed in a drying oven at 50ºC for 72 hours. Afterwards, the curved edges of the specimens were covered with an adhesive tape. The specimens were then sealed and kept until 27 days in the drying oven, at the same temperature, for humidity redistribution. After that, they were placed in a laboratory room at 65% RH for 24 hours, in order to reduce their temperature to 20º C, and placed in a tin with water for the capillary absorption test, which has been carried out following procedure 4.2 of reference (7). However, the water uptake has been measured at time intervals of 15 minutes, 30 minutes, 1 h, 2 h, 4 h, 8 h, 24 h, and 48 h. 2.3. Natural exposure tests For each concrete mixture, 100 × 100 × 510 mm concrete prisms have been cast. After 7 days in moist curing, the specimens have been kept under standard laboratory conditions (21±3ºC and 60±5% RH) for 14 days before natural exposure initiation. An epoxy-based coating was applied on two opposite lateral surfaces of the concrete prisms to obtain unidirectional penetration of aggressive agents. Two prisms from each concrete mixture have been exposed to the three field conditions: marine atmosphere (airborne salt zone), tidal zone and permanently immersed in the seawater. After 6 months of exposure, powder samples extracted at different depths from each prism have been analysed using the same increments of sampling and analysis techniques indicated on Method B. From the two chloride profiles obtained for each concrete mixture in the three environments, the chloride transport coefficients have been estimated adjusting the solution of Fick’s 2nd Law, given by equation [3]. 3. Results and Discussion Table 6 summarises the results obtained for the ASTM charge transported, resistivity, colorimetric chloride front depth (after ASTM test), and capillary absorption. Table 7



presents the results of chloride diffusion coefficients, obtained on laboratory specimens at 28 days of age, from the three test methods. Some relationships can be achieved between results from all the performance tests and W/C ratio and compressive strength, Figs.1 to 6. With the cement content, no correlation at all was found for the different properties. For resistivity, charge transported, capillary absorption, and non-steady state chloride diffusion coefficients obtained by methods A and B, very good correlation has been achieved, for concrete mixtures with the two types of cement. Good correlations have been also obtained for other environments, where the durability is related mainly with carbonation (8). Despite the different results obtained with CEM I and CEM IV/B concrete mixtures, it can be seen that for each property, the shape of the correlation curves is similar for both cements. This may indicate a standard behaviour, which could be extrapolated to other cement types. The values presented for the different performance properties clearly show that it is possible to use them to classify different concrete mixtures. In fact, different concrete mixtures present distinct properties, but, generally, all the properties lead to a similar ranking for concrete mixtures. It seems also that there is no loss of sensitivity to distinguish concretes with different compositions, when replacing the design parameters specified in terms of the concrete composition, by performance-related properties. The chloride profile obtained for a concrete mixture in natural exposure depends on the chloride diffusivity of the concrete, of the aggressiveness of environment and on the time of exposure. The shape of the chloride profiles obtained after 6 months of natural exposure are different for the various concrete mixtures. Concrete mixtures with the highest capillary absorption values (specially A1 and A2) show a more flat profile in the first 15 to 20 mm from the surface. This effect, more pronounced for specimens submerged or in the tidal zone, indicates that for 6 months of exposure, chloride ingress is dominated by the water absorption process. Table 8 shows the chloride transport coefficients estimated from the chloride profiles. As expected, the highest chloride diffusion coefficients in natural exposure have been obtained for concrete permanently submerged in seawater (not very different from tidal zone values) and the lowest for concrete exposed to the marine atmosphere, due to the differences in the chloride content and in the contribution of water transport processes in these environments. However, these differences in the achieved diffusion coefficients are more significant for mixtures with the highest W/C ratios, probably due to the significant contribution of water absorption in these mixtures. However, the same ranking of concrete mixtures is also achieved with the chloride diffusion obtained in natural exposure.



Figs. 7 and 8 show the relations between chloride diffusion coefficients obtained in non-steady state conditions and in natural exposure. The best correlations have been achieved with the coefficients obtained from methods A and B. Comparing the three types of non-steady state chloride diffusion coefficients it can be pointed out that:

- there was no significant influence of type of cement, Table 7; - the coefficients obtained from the three methods are of the same order of

magnitude; - Dns values obtained from methods A and B, as shown in Figs. 4 and 5, give the

best correlations with W/C ratio and compressive strength. One of the reasons for the poor correlations obtained for the diffusion coefficients from method C can be related to the very reduced age of concrete at the beginning of the test (28 days) and to the excessive duration used for the ponding of concrete specimens in chloride solution (2 and 4 months), when compared with the delay in the hydration processes especially for concrete mixtures with CEM IV;

- values of chloride diffusion coefficients obtained from the methods A and B, are identical, except for concrete mixtures A1 and A2, with the highest ASTM charge . In fact, the application to these compositions of the electrical field (60 Vdc) used on method A introduces an additional acceleration factor on the chloride ingress due to the increase in temperature by Joule effect which is more pronounced with this mixtures ( an increase of the temperature around 40ºC has been measured) .

4. Conclusions Based on the results obtained in this study the following conclusions can be drawn: • Of the performance concrete properties tested: ASTM charge transported, concrete

resistivity, and chloride diffusion coefficients obtained in non-steady state conditions under migration and capillary absorption are useful to distinguish concrete mixtures with different concrete compositions and different resistances to chloride ingress. The results obtained confirm other previous conclusions (8), that the resistivity of concrete, measured in standard conditions of humidity and temperature, can be an easier alternative to the use of the charge transported by the ASTM C1202, as a parameter for evaluation of the resistance to chloride ingress and also for ranking the concrete mixtures.

• In general, the performance concrete properties have shown good relationships with the behaviour in marine exposure of the different concrete mixtures.. It seems that it is possible, when results for a longer exposure time have been obtained, to establish limit values for these properties, applicable to the different classes of exposure and correlated with those predicted. These limit values could be used in performance-related design methods for new structures and to develop models for service lifetime estimation in reinforced concrete.



• Regarding the methods to obtain chloride diffusion coefficients in non-steady state conditions, results obtained show that the application of a migration method under a lower electrical field (≤ 30 Vdc) correlates better with the concrete chloride transport coefficients in natural environment. However, all of the methods tested give very high values for chloride diffusion coefficients (Dns) when compared with the achieved chloride diffusion coefficient in concrete mixtures exposed in natural conditions. This indicates that the acceleration effect is very significant in the three methods tested. For longer times of exposure, a decrease in the natural achieved chloride diffusion coefficient is expected. For this reasons to model chloride transport in concrete, using non-steady coefficients data from laboratory, other factors must be considered, namely, the effect of the environment aggressiveness, the acceleration effect associated with the chloride diffusion obtained in the laboratory test used and the evolution of concrete micro-structure. Otherwise, big errors can occur on the estimation of service lifetime.

Acknowledgements This study has been developed under the LNEC I&D Research Plan for 2001-2004, with financial support of the Portuguese Government.(PIDDAC). The authors extend their gratitude to co-workers, Ana Paula Melo, Nuno Garcia , Angela Machado, João Balsinha and Victor Fialho for their co-operation in the experimental work. References 1. EN 206-1 – concrete – Part 1: Specification, performance, production and

conformity, European committee for standardization, December 2000. 2. CEN–European Committee for Standardization, “EN 197-1, Cement Part–1:

Composition, specifications and conformity criteria for common cements”; April 2001, 35 pp.

3. ASTM C 1202 – Standard test method for electrical indication of concrete´s ability to resist chloride ion penetration – ASTM, Vol. 04.02, Phildelphia , 1998. pag 620.

4. Collepardi, M.; “Quick method to determine free and bound chlorides in concrete” Proc. of the Int. RILEM Workshop on Chloride penetration into concrete, St. Rémy-lès-Chevreuse,1995, p. 10-16.

5. NT Build 492 – Concrete, Mortar and Cement- Based Repair Materials: Chloride Migration coefficient from non-state migration experiments, Publisher NORDTEST, Espoo, 1998, 8 pp.

6. NT Build 443 – Concrete, Hardened: Accelerated Chloride penetration, Publisher NORDTEST, Espoo, 1995, 4 pp.

7. RILEM TC 116-PCD, “Permeability of concrete as a criterion of its durability”; Materials and Structures, Vol. 32, April 1999, pp. 174-179.



8. Ribeiro, A. B.; Gonçalves ,A.; Salta, M. M and Machado, A.; Performance of Concrete with an Intended Working Life of 50 Years, Paper to be presented at CANMET 2003 Conference.

9. Salta, M.M.; “Caracterização da resistência do betão à penetração de cloretos”; COLLOQUIA 2001, Madrid, 2001.

Table 1 - Chemical analyses on CEM I 32.5 R and CEM IV/B 32.5, %.

Component CEM I 32.5 R CEM IV/B 32.5 SiO2 Al2O3 Fe2O3 CaO MgO K2O Na2O C3S* C2S* C3A* C3AF*

19.99 5.74 3.02 60.79 1.57 0.28 0.15 45.83 22.74 10.10 9.19

11.94 3.43 1.8 36.71 0.94 0.17 0.09 - - - -

Loss on ignition Insoluble residue Sulphates (SO3) Chlorides

3.56 2.22 2.40 0.020

3.17 32.96 2.00 0.020

*According to Bogue expression

Table 2 - Composition of CEM I 32.5 R and CEM IV/B 32.5.

Cement Clinker %

Filer %

Fly ash %

Calcium sulphate %

CEM I 32.5 R 90.92 5 - 4.08 CEM IV/B 32.5 54.3 3 39.3 3.4



Table 3 - Properties of aggregates.

Aggregate Bulk specific gravity (kg/m3)

Fineness modulus

Maximum size (mm)

Absorption (%)

Coarse aggregate 1

2670 6.22 12.7 0.88

Coarse aggregate 2

2690 7.23 26.1 0.57

Sand 2600 2.63 2.9 - Table 4 - Proportions of concrete mixtures.

Concrete mixture Materials (kg/m3) A1 B1 C1 D1 A2 B2 C2 D2 Coarse

aggregate 1 316 329 345 513 336 348 368 548

Coarse aggregate 2

796 865 867 735 799 871 875 745

Sand 788 719 657 389 732 656 587 279 CEM I 32.5 R 260 300 340 530 - - - -

CEM IV/B 32.5 R

- - - - 260 300 340 530

Silica fume - - - 50.7 - - - 50.7 Water 169.3 150.7 153.3 177.3 169.3 151.9 153.3 177.3

Pozzolith 390 N 2.51 - - - 2.51 - - - Rheobuild 1000 - 3.60 4.11 - - 3.60 4.11 -

Glenium 27 - - - 13.3 - - - 13.3 Slump (mm) 70 130 180 120 150 180 180 140

W/C 0.65 0.50 0.45 0.30* 0.65 0.50 0.45 0.30* Compressive strength, 28 days (MPa)

36.9 49.6 52.9 80.7 32.4 46.4 52.5 76.2

*Silica fume included



Table 5 - Location of natural exposure of concrete specimens, concrete composition and exposure classes according to EN 206-1.

Concrete composition

Location of concrete

specimens

Type of attack

Exposure Class

according EN 206-1

Maximum W/C

Minimum strength

class

Minimum cement content (kg/m3)

Marine atmosphere (Sea water

airborne salt)

chloride and carbonation

XS1 -

0.50 C30/37 300

Marine tidal zone

chloride XS3 0.45 C35/45 340

Permanently submerged

chloride XS2 0.45 C35/45 320

Table 6- Tests results of laboratory specimens at 28 days.

Laboratory tests Concrete mixture Capillary

absorption coefficient

(kg/m2h1/2)(1)

ASTM C1202Charge (2)

(Coulomb)

Colorimetric chloride front (2) (ASTM

C1202) (mm)

Resistivity (2)

(Ω.m)

A1 0.532 ± 0.051 6418 ± 573 55 ± 0.0 58 ± 8 B1 0.215 ± 0.021 4157 ± 367 27 ± 0.9 97 ± 10 C1 0.245 ± 0.024 3694 ± 12 23 ± 0.6 84 ± 2 D1 0.092 ± 0.001 1311 ± 95 5.6 ± 0.4 242 ± 7 A2 0.733 ± 0.042 4968 ± 331 50 ± 0.0 150 ± 10 B2 0.254 ± 0.017 2214 ± 174 18.3 ± 2.3 158 ± 8 C2 0.206 ± 0.017 1827 ± 208 16.6 ±1.7 179 ± 19 D2 0.187 ± 0.030 744 ± 37 6 ± 1.7 323 ± 10

(1) mean value and sd of 6 results (2) mean value and sd of 3 results



Table 7 -Concrete chloride diffusion coefficients measured at 28 days in non-steady state conditions.

Concrete mixture

Method A (ASTM+Color.)

Dns x10-12 (1)

(m2/s)

Method B (NT Build 443) Dns x10-12

(2) (m2/s)

Method C (NT Build 492) Dns x10-12

(1) (m2/s)

A1 88.6 ± 1.3 58.4 40.9 ± 2.0 B1 21.1 ± 0.5 10.5 15.4 ± 1.7 C1 16.0 ± 0.9 29.6 21.3 ± 2.0 D1 0.81 ± 0.1 2.6 2.7 ± 0.2 A2 72.4 ± 0.2 31.0 41.6 ± 1.4 B2 10.8 ± 1.5 2.6 11.0 ± 1.2 C2 7.1 ± 0.2 8.8 10.8 ± 0.2 D2 0.74 ± 0.2 6.0 1.3 ± 0.0

* from colorimetric front (1) medium from 3 tests (2) medium from 2 tests

Table 8 - Concrete chloride diffusion coefficient at 6 months of natural exposure.

D x10-12 (1)

(m2/s) Concrete mixture Marine

atmosphere (airborne salt)

Tidal Submerged

A1 2.2 *

12.3 5.6

24.2 17.2

B1 1.6 2.2

4.6 3.9

4.9 8.6

C1 3.1 2.1

2.4 5.2

1.8 7.0

D1 0.4 0.2

0.6 0.7

0.8 1.3

A2 3.6 *

4.9 7.9

13.0 8.8

B2 2.0 1.1

2.0 2.6

4.4 11.1

C2 1.5 2.0

1.3 2.2

1.2 5.3

D2 0.6 0.4

1.2 0.8

1.1 1.1

*non-calculated value



Fig. 1 – ASTM charge versus W/C ratio, the binder dosage and the compressive strength for CEM I 32.5 R and CEM IV/B 32.5 concrete mixtures.

y = 151,73e5,39x

R2 = 1,00

y = 398,70e4,49x

R2 = 0,93

0

2000

4000

6000

8000

0,20 0,40 0,60 0,80

W/C

AST

M C

harg

e (C

oulo

mb)

CEM I 32,5 R CEM IV 32,5

0

2000

4000

6000

8000

100 300 500

Cement content (kg/m3)

AST

M C

harg

e (C

oulo

mb)


y = 17686,52e-0,04x

R2 = 0,98

y = 25074,22e-0,04x

R2 = 1,00

0

2000

4000

6000

8000

0 20 40 60 80 100

Compression strength (MPa)

AST

M C

harg

e (C

oulo

mb)




Fig. 2 – Resistivity of the concrete versus W/C ratio, the binder dosage and the compressive strength for CEM I 32.5 R and CEM IV/B 32.5 concrete mixtures.

y = 540,16e-2,1 7x

R2 = 0,82

y = 627,61e-3,79x

R2 = 0,840

50

100

150

200

250

300

350

0,20 0,40 0,60 0,80

W/C

Resi

stiv

ity (

m)


0

50

100

150

200

250

300

350

100 200 300 400 500 600

Cement content (kg/m3)Re

sist

ivity

(m

)


y = 75,15e0,02x

R2 = 0,92

y = 18,27e0,03x

R2 = 0,95

0

50

100

150

200

250

300

350

0 20 40 60 80 100


Resi

stiv

ity (

m)




Fig. 3 - Capillary absorption versus W/C ratio, the binder dosage and the compressive strength for CEM I 32.5 R and CEM IV/B 32.5 concrete mixtures.

y = 0,05e3,91x

R2 = 0,80

y = 0,02e4,85x

R2 = 0,95

0

0,2

0,4

0,6

0,8

0,20 0,40 0,60 0,80

W/C

Capi

llary

abs

orpt

ion

(kg/

m2 h1/

2 )


0

0,2

0,4

0,6

0,8

100 200 300 400 500 600

Cement content (kg/m3)

Capi

llary

abs

orpt

ion

(kg/

m2 h1/

2 )


y = 1,26e-0,03x

R2 = 0,67

y = 1,79e-0,04x

R2 = 0,94

0

0,2

0,4

0,6

0,8

0 20 40 60 80 100


Capi

llary

abs

orpt

ion

(kg/

m2 h1/

2 )




Fig. 4 – Diffusion coefficient estimated in laboratory by Method A (ASTM+Color) versus W/C ratio, the binder dosage and the compressive strength for CEM I 32.5 R and CEM IV/B 32.5 concrete mixtures.

y = 0,02e13,01x

R2 = 0,99

y = 0,03e12,83x

R2 = 0,93

0,00

25,00

50,00

75,00

100,00

0,20 0,40 0,60 0,80

W/C

Dns

(AST

M C

olor

) (x1

0-12 m

2 /s)


0,00

25,00

50,00

75,00

100,00

100 200 300 400 500 600

Cement content (kg/m3)Dn

s (A

STM

Col

or) (

x10-1

2 m2 /s

)CEM I 32,5 R CEM IV 32,5

y = 1628,12e-0,10x

R2 = 0,99

y = 3702,49e-0,10x

R2 = 1,00

0,00

25,00

50,00

75,00

100,00

0 20 40 60 80 100


Dns

(AST

M C

olor

) (x1

0-12 m

2 /s)




Fig. 5 – Diffusion coefficient estimated in laboratory by Method B (NT BUILD 492) versus W/C ratio, the binder dosage and the compressive strength for CEM I 32.5 R and CEM IV/B 32.5 concrete mixtures.

y = 0,09e9,78x

R2 = 0,96

y = 0,39e7,52x

R2 = 0,86

0,00

10,00

20,00

30,00

40,00

50,00

0,20 0,40 0,60 0,80

W/C

Dns

(NT

Build

492

) (x1

0-12 m

2 /s)


0,00

10,00

20,00

30,00

40,00

50,00

100 200 300 400 500 600


s (N

T Bu

ild 4

92) (

x10-1

2 m2 /s


y = 517,88e-0,08x

R2 = 0,98

y = 420,07e-0,06x

R2 = 0,96

0,00

10,00

20,00

30,00

40,00

50,00

0 20 40 60 80 100


Dns

(NT

Build

492

) (x1

0-12 m

2 /s)




Fig. 6 – Diffusion coefficient estimated in laboratory by Method C (NT BUILD 443) versus W/C ratio, the binder dosage and the compressive strength for CEM I 32.5 R and CEM IV/B 32.5 concrete mixtures.

y = 1,15e4,11x

R2 = 0,33

y = 0,29e8,27x

R2 = 0,78

0,00

25,00

50,00

75,00

100,00

0,20 0,40 0,60 0,80

W/C

Dns

(NT

Build

443

) (x1

0-12 m

2 /s)


0,00

25,00

50,00

75,00

100,00

100 200 300 400 500 600


s (N

T Bu

ild 4

43) (

x10-1

2 m2 /s


y = 32,83e-0,03x

R2 = 0,23

y = 602,82e-0,07x

R2 = 0,85

0,00

25,00

50,00

75,00

100,00

0 20 40 60 80 100


Dns

(NT

Build

443

) (x1

0-12 m

2 /s)




Fig. 7 –Diffusion coefficients estimated in laboratory versus chloride diffusion coefficients achieved after 6 months of exposure for concretes with cement type CEM I 32.5 R.

CEM I 32,5 R

y = 4,0245x + 2,357R2 = 0,8768

y = 2,6536x + 4,961R2 = 0,9263

y = 6,7251x - 6,6607R2 = 0,995

0,00

20,00

40,00

60,00

80,00

100,00

0 5 10 15 20D natural, tidal (x10-12 m2/s)

D la

b.,

(x10

-12 m

2 /s)

Color NT Build 492 NT Build 443

CEM I 32,5 R

y = 16,541x - 3,5303R2 = 0,4273

y = 11,796x - 0,4685R2 = 0,528

y = 18,766x - 1,0492R2 = 0,2235

0,00

20,00

40,00

60,00

80,00

100,00

0 1 2 3 4D natural, airborne (x10-12 m2/s)

D la

b.,

(x10

-12 m

2 /s)


CEM I 32,5 R

y = 2,5902x + 3,9314R2 = 0,8159

y = 1,724x + 5,8667R2 = 0,8782

y = 4,4887x - 5,3494R2 = 0,9957

0,00

20,00

40,00

60,00

80,00

100,00

0 5 10 15 20 25D natural, submerged (x10-12 m2/s)

D la

b.,

(x10

-12 m

2 /s)




Fig. 8 – Diffusion coefficients estimated in laboratory versus chloride diffusion coefficients achieved after 6 months of exposure for concretes with cement type CEM IV/B 32.5 R.

CEM IV 32,5

y = 4,9857x - 2,313R2 = 0,8753

y = 7,2217x - 4,7096R2 = 0,9893

y = 13,73x - 16,937R2 = 0,9901

0,00

20,00

40,00

60,00

80,00

100,00

0 2 4 6 8D natural, tidal (x10-12 m2/s)

D la

b.,

(x10

-12 m

2 /s)


CEM IV 32,5

y = 8,9197x - 4,3334R2 = 0,7914

y = 13,44x - 8,5934R2 = 0,9678

y = 24,551x - 22,477R2 = 0,8942

0,00

20,00

40,00

60,00

80,00

100,00

0 1 2 3 4 5D natural, airborne (x10-12 m2/s)

D la

b.,

(x10

-12 m

2 /s)


CEM IV 32,5

y = 1,9628x + 0,8072R2 = 0,453

y = 3,4709x - 3,8015R2 = 0,763

y = 6,3706x - 13,898R2 = 0,7117

0,00

20,00

40,00

60,00

80,00

0 5 10 15D natural, submerged (x10-12 m2/s)

D la

b.,

(x10

-12 m

2 /s)




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