SIST ISO/DIS 1920-11:2012
Testing of concrete -- Part 11: Determination of the chloride resistance of concrete, unidirectional diffusion
Testing of concrete -- Part 11: Determination of the chloride resistance of concrete, unidirectional diffusion
ISO 1920-11:2013 specifies a method for determining the unidirectional non-steady-state chloride penetration parameters of conditioned specimens of hardened concrete. The test method enables the determination of the chloride penetration at a specified age, e.g. for ranking of concrete quality by comparative testing.
Essais du béton -- Partie 11: Détermination de la résistance du béton à la pénétration des chlorures, diffusion unidirectionnelle
[Not translated]
General Information
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 1920-11
First edition
2013-05-01
Testing of concrete —
Part 11:
Determination of the chloride
resistance of concrete, unidirectional
diffusion
Essais du béton —
Partie 11: Détermination de la résistance du béton à la pénétration
des chlorures, diffusion unidirectionnelle
Reference number
ISO 1920-11:2013(E)
©
ISO 2013
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ISO 1920-11:2013(E)
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ISO 1920-11:2013(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Reagents and apparatus . 3
5.1 Reagents. 3
5.2 Apparatus . 4
6 Preparation of specimens . 5
6.1 Preparing sub-specimens . 5
6.2 Conditioning and preparation of profile specimen for chloride testing . 6
7 Procedure. 7
7.1 Exposure conditions . 7
7.2 Exposure method . 8
7.3 Exposure period . 8
7.4 Determination of initial chloride content (C ) . 8
i
7.5 Profile grinding . 9
7.6 Chloride analysis . 9
8 Regression procedure and expression of results . 9
9 Test report .11
10 Precision .12
Annex A (informative) Diffusion coefficients.13
Annex B (informative) Core test specimen .14
Annex C (normative) Immersion method for large specimens .15
Annex D (informative) Typical equipment and procedure for vacuum saturation .16
Annex E (informative) Procedures of specimen exposure to chloride solution .18
Annex F (informative) Depth intervals of profile specimen grinding .20
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ISO 1920-11:2013(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2. www.iso.org/directives
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received. www.iso.org/patents
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
The committee responsible for this document is ISO/TC 71, Concrete, reinforced concrete and prestressed
concrete, Subcommittee SC 1, Test methods for concrete.
ISO 1920 consists of the following parts, under the general title Testing of concrete:
Part 1: Sampling of fresh concrete
Part 2: Properties of fresh concrete
Part 3: Making and curing test specimens
Part 4: Strength of hardened concrete
Part 5: Properties of hardened concrete other than strength
Part 6: Sampling, preparing and testing of concrete cores
Part 7: Non-destructive tests on hardened concrete
Part 8: Determination of drying shrinkage of concrete for samples prepared in the field or in the laboratory
Part 9: Determination of creep of concrete cylinders in compression
Part 10: Determination of static modulus of elasticity in compression
Part 11: Determination of the chloride resistance of concrete, unidirectional diffusion
Part 12: Determination of the carbonation resistance of concrete — Accelerated carbonation method
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ISO 1920-11:2013(E)
Introduction
Steel reinforced concrete structures exposed to the ingress of chloride, either from seawater or other
sources, need to be durable for at least the intended service life. The possibility of reinforcement
corrosion is significantly increased as the chloride level at the embedded reinforcement increases. For
this reason, the chloride diffusivity or chloride penetrability of the concrete is an important property to
measure and this International Standard sets out a test method that may be applied to specimens cast
to assess the potential chloride resistance of a concrete mix.
NOTE This test method takes a minimum of 119 days comprising a minimum age of the specimen prior to
testing of 28 days, a minimum of one day to prepare and condition the specimen and then 90 days to expose the
specimen to the chloride solution. Different periods of curing and exposure may be set (and stated in the test
report) in order to adjust the test duration.
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INTERNATIONAL STANDARD ISO 1920-11:2013(E)
Testing of concrete —
Part 11:
Determination of the chloride resistance of concrete,
unidirectional diffusion
1 Scope
This part of ISO 1920 specifies a method for determining the unidirectional non-steady-state chloride
penetration parameters of conditioned specimens of hardened concrete. The test method enables the
determination of the chloride penetration at a specified age, e.g. for ranking of concrete quality by
comparative testing.
NOTE 1 The aim of the test is to assess the potential resistance to chloride ingress for a concrete mix.
NOTE 2 Since resistance to chloride penetration depends on ageing, due to the effects of continual hydration of
the concrete, the ranking may also change with age.
2 Normative references
The following referenced documents are essential for the application of this part of ISO 1920. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 1920-3, Testing of concrete — Part 3: Making and curing test specimens
ISO 1920-6, Testing of concrete — Part 6: Sampling, preparing and testing of concrete cores
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
as-cast surface
surface of a concrete element exposed in the construction works to a chloride environment
3.2
acid-soluble chloride content
amount of acid-soluble chloride expressed in percent by mass of concrete
3.3
chloride penetration
ingress of chlorides into concrete due to exposure to external chloride sources
3.4
diffusion
movement of molecules or ions under a concentration gradient, from a zone of high concentration to a
zone with a lower concentration
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ISO 1920-11:2013(E)
3.5
diffusion coefficient
proportionality between the molecular flux (e.g. rate of flow of chloride ions) and the concentration
gradient in the diffusion equation
Note 1 to entry: In this part of ISO 1920, Fick’s Law is adopted as a valid mathematical representation of the
chloride ingress mechanism.
Note 2 to entry: See Annex A.
3.6
initial chloride content, C
i
chloride content at a distance sufficiently remote from the surface as to not have been influenced by
penetration of the chloride exposure solution
Note 1 to entry: It reflects the initial chloride content that came from the constituents when the concrete was mixed.
3.7
non-steady state diffusion coefficient, D
nss
diffusion coefficient that takes into account simultaneous chloride binding
Note 1 to entry: This reflects the rate of diffusion of chloride into a concrete when part of the chloride is being
bound by the cement.
Note 2 to entry: See Annex A.
Note 3 to entry: The steady-state chloride diffusion coefficient is measured on water saturated samples where
chloride diffuses through a thin specimen between two reservoirs of chloride solution, where one reservoir is
at a higher concentration than the other. This steady-state chloride diffusion is not covered by this test method.
The steady-state chloride diffusion coefficient only reflects the ionic transport diffusion through concrete, as the
concrete is unable to bind any more chloride ion.
3.8
profile grinding
dry process grinding a concrete specimen in thin successive layers
3.9
vacuum saturated condition
specimen that is vacuum saturated with water
4 Principle
A specimen, either a cylinder or cube, is cast and cured in accordance with ISO 1920-3 (see also
amendments of the curing conditions in 6.1), for a standard curing period of 28 days.
NOTE 1 A curing period of less than 28 days may be set, depending on the type of cement and purpose of the test.
Annex B gives guidance on the testing of core specimens, where the core may be sampled from a test
element, a precast concrete element or a structure.
The specimen is divided into two sub-specimens: a “profile specimen” that is used to determine the
chloride profile after exposure to unidirectional chloride ingress, and an initial chloride sub-specimen
that is used to determine the initial chloride level, C . This initial figure is taken as the chloride level of
i
the cast concrete.
The profile specimen is vacuum saturated with distilled or demineralized water, coated on all sides but
one and then the uncoated face is exposed to a chloride exposure solution. The exposure is achieved by
total immersion of the specimen in the chloride exposure solution.
NOTE 2 The test can be performed without vacuum saturating the profile specimen in water; this should be
stated in the test report.
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ISO 1920-11:2013(E)
NOTE 3 The exposure can be achieved by alternative methods, that are:
a) ponding the uncoated face of the specimen in the chloride exposure solution;
b) inverting the specimen and having the uncoated face immersed in the chloride exposure solution.
NOTE 4 The use of large fully immersed specimens is described in Annex C.
The standard reference solution is a 3 % by mass, sodium chloride (NaCl) solution, for an exposure
period of 90 days. The solution concentration will be kept constant during the test.
NOTE 5 Other concentrations or solutions, e.g. artificial seawater, and exposure periods other than 90
days, may be set.
After the specified period of exposure, at least eight parallel layers of the chloride exposed surface are
ground off the profile specimen. The acid-soluble chloride content of each layer and the average depth
of the layer from the surface of the concrete exposed to the chloride solution are determined. The initial
chloride content is determined by grinding a sample from the other sub-specimen and having the acid-
soluble chloride content determined.
The surface chloride content (C ) and the non-steady-state chloride diffusion coefficient (D ) are
s nss
determined by nonlinear regression analysis using the least squares curve fitting procedure.
Because of the high coefficient of variation, approximately 15 % for D for the test, testing of three
nss
specimens is required and the results reported separately.
NOTE 6 The chloride diffusion coefficient varies with the age of the concrete and the period of exposure.
NOTE 7 The diffusion test described in this part of ISO 1920 is only valid for a constant initial chloride content.
NOTE 8 When precision information is available for this test, a check on the validity of the two or more results
will be introduced plus the determination of the average value.
5 Reagents and apparatus
5.1 Reagents
Reagents of analytical quality shall be used.
NOTE Unless otherwise stated, “percent” means percent by mass.
5.1.1 Calcium hydroxide, Ca(OH)
2
5.1.2 Chloride exposure solution
a) Reference solution
Dissolve 30 g of analytical quality NaCl in 970 g of distilled or demineralized water having an
−1
electrical conductivity ≤ 0,5 mSm at 20 °C to produce a 3 % by mass NaCl solution. Store it in a
clean container.
NOTE This NaCl solution has a similar chloride concentration to that of seawater.
b) Other exposure solutions
Where the concentration of the chloride exposure solution is other than that in 5.1.2 a), the
concentration shall be recorded and reported. Where a different solution is used, the composition
of the solution shall be recorded and reported.
NOTE 1 Natural and artificial seawater have been used to reflect the exposure of the construction works.
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ISO 1920-11:2013(E)
NOTE 2 Higher concentrations of NaCl, such as 16,5 %, and shorter exposure periods (e.g. 35 days) may be
used to accelerate the development of a chloride profile.
5.1.3 Chloride impervious barrier system
A polyurethane or epoxy-based paint or equivalent barrier system highly resistant to chloride diffusion,
to be used in sealing the sides of the specimen.
5.1.4 Chemicals for chloride analysis, complying to a national standard valid in the place of use. The
reference number of the national standard shall be stated in the test report.
−1
5.1.5 Distilled or demineralized water, having an electrical conductivity ≤ 0,5 mSm .
5.2 Apparatus
5.2.1 Water cooled diamond saw
5.2.2 Balance for weighing NaCl and water, capable of weighing to an accuracy of ± 0,1 g.
5.2.3 Thermometer, capable of measuring to an accuracy of ± 1 °C.
5.2.4 Temperature controlled chamber, capable of keeping a temperature of (20 ± 2) °C.
5.2.5 Where used, a polyethylene container with airtight lid for immersion of the profile
specimen. The volume of the exposure solution shall exceed the volume of the specimen by not less
than 12,5 ml per square centimetre of exposed surface. A container may contain more than one sample
provided the ratio of exposure solution to exposed surface shall be recorded and reported.
NOTE During the test, the chloride concentration of the chloride exposure solution reduces and if the ratio of
the volume of chloride exposure solution to exposure surface varies, the rate of reduction will vary with nominally
identical concrete. For this reason if a direct comparison of results from different specimens is required, the ratio
of the volume of chloride exposure solution to exposed surface should be constant.
5.2.6 Where used, pond to be attached to profile specimen. The ponds shall have a constant
diameter and initial depth not less than 125 mm.
5.2.7 Equipment for grinding off and collecting concrete powder in layers 1 mm or more deep,
2
capable of grinding a surface area of at least 4000 mm and not grinding within 10 mm of the edge of
the test area.
5.2.8 Compressed air or air blower, to clean dust from specimen and equipment between grinding layers.
5.2.9 Dust collecting bags
5.2.10 Equipment for chloride content testing, in accordance with a national standard valid in the
place of use. The reference number of the national standard shall be stated in the test report.
5.2.11 Calliper, measuring to an accuracy of ± 0,1 mm.
5.2.12 Vacuum container, capable of containing at least three specimens.
5.2.13 Vacuum pump, capable of maintaining an absolute pressure of less than 50 mbar (5 kPa) in the
container, e.g. a water-jet pump.
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ISO 1920-11:2013(E)
6 Preparation of specimens
6.1 Preparing sub-specimens
A specimen size shall be selected such that after cutting, the minimum dimension of the sub-specimens
used to determine a chloride profile is at least three times the nominal maximum aggregate size. Three
specimens, either cylinders, 100 mm or greater in diameter or cubes, 100 mm or greater are cast, and
cured for a period of 28 days in a water filled bath with a temperature of (20 ± 2) °C, in accordance
with ISO 1920-3. In hot climate locations, the curing conditions after removal of the specimen from the
mould can be different from those mentioned in ISO 1920-3. In this case, the specimens may be stored in
water at a temperature of (27 ± 2) °C or in a chamber having a temperature of (27 ± 2) °C and a relative
humidity of at least 95 %.
NOTE A curing period other than 28 days may be set, depending on the type of cement and purpose of the test.
After 28 days of standard curing or the specified curing period (see the above note), each cylinder or
cube is cut into two sub-specimens using the water cooled diamond saw. Cylindrical specimens are cut
in the direction parallel to the flat surface and cubical specimens are cut in the direction parallel to the
top (trowelled) surface as shown in Figure 1. No dimension of the sub-specimens used to determine a
chloride profile shall be less than three times the nominal maximum aggregate size. One sub-specimen
(called the “profile specimen”) is used to determine the chloride profile, and the initial chloride sub-
specimen is used to determine the initial chloride content. This initial chloride content is taken as being
the chloride content of the cast concrete. The adjacent sawn faces are used to determine these values.
NOTE 2 Where a chloride profile is required that incorporates the effect of a formed surface then a formed
surface from a cube specimen may be specified as the surface for chloride exposure. However, the results from
such a procedure are difficult to interpret due to concentrations of cement paste and chloride at the formed
surface. The use of this approach should be reported under Clause 9, m), as it is a non-standard test condition.
Key
1 trowelled surface
2 cut to separate specimens and produce exposure surface
Figure 1 — Specimen preparation
After sawing, the sub-specimen to be used to determine the initial chloride content shall be placed in a
close fitting sealed plastic bag or tested immediately.
Where needed, the sub-specimens may be cut to reduce their size to aid handling, but the sub-specimen
for determining the chloride profile shall not have a dimension less than three times the nominal
maximum aggregate size.
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ISO 1920-11:2013(E)
6.2 Conditioning and preparation of profile specimen for chloride testing
6.2.1 Vacuum saturation of the profile specimens
After sawing the specimens, vacuum saturate the profile specimens with water. Annex D shows a typical
arrangement for vacuum saturation. Place the profile specimens in the vacuum container and reduce
the absolute pressure to a value between 10 mbar and 50 mbar (1 kPa to 5 kPa) within a few minutes
of closing the container. Maintain this absolute pressure for 3 h and then with the vacuum pump still
running, fill the container with distilled or demineralized water so that all the profile specimens are
immersed. Maintain the absolute pressure for a further hour before allowing air to re-enter the container.
Leave the profile specimens immersed in water until the process of surface sealing starts.
The test may be carried out without vacuum saturating the profile specimen in water, as described in
this clause. If the profile specimen is not vacuum saturated in water, this shall be mentioned in the test
report in order to allow comparison of the test results obtained by the same procedure.
6.2.2 Sealing surfaces other than the surface to be exposed
6.2.2.1 General
Start the sealing within 24 h of completing the vacuum saturation or the standard curing (if no vacuum
saturation was carried out). All surfaces of the profile specimen except for the sawn face shall be sealed,
see Annex C for an exception. After sealing the surfaces, place the specimens in saturated calcium
hydroxide solution for at least 18 h.
NOTE The purpose of sealing the faces other than the face exposed to the chloride solution is to ensure
that the ingress of chloride ions into the concrete is a pure unidirectional diffusion process and not a mixture of
diffusion and other processes, e.g. capillary suction.
6.2.2.2 Sealing procedures
a) Specimens exposed to chloride solution by immersion – standard reference method.
The profile specimen shall be dried in laboratory air until its surface is “white-dry”.
NOTE This usually takes between 2 h and 4 h.
All faces except the face to be exposed to the chloride solution shall be coated with a layer of epoxy
or polyurethane or equivalent making sure that the surface to be tested remains free of the coating
material. The coating material shall be applied and cured in accordance with the recommendations of
the manufacturer.
b) Specimens exposed to the chloride solution by alternate methods.
1) Exposure by ponding:
i) as described in 6.2.2.2 a) for specimens exposed by immersion, or
ii) dry the surfaces with a cloth to remove free water and wrap the surface with one or
three layers of a polymeric or composite self-amalgamating tape with a low water vapour
transmission rate (for instance aluminium foil tape or parafinated polymeric film), ensuring
sufficient overlap of joints.
NOTE If one layer is applied, 7.2.2 b) requires additional protection.
2) Exposure by inversion:
i) as described in 6.2.2.2 a) for specimens exposed by immersion.
6.2.3 Exposure of specimens to the chloride solution
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ISO 1920-11:2013(E)
a) Profile specimen for immersion – standard reference method.
After storage in saturated calcium hydroxide solution, the specimen shall be transferred directly to
exposure without surface drying. A suitable arrangement is shown in Annex E.
b) Profile specimen for exposure by alternative methods.
1) Profile specimen for ponding:
After storage in saturated calcium hydroxide solution, a pond is sealed to the surface of the
specimen in a manner that prevents leakage of the chloride exposure solution. A suitable
arrangement is shown in Annex E, noting that the volume of the pond is as defined in 5.2.6.
The external border between the plastic tube and specimen is sealed to prevent leakage. The
diameter of the tube used to form the pond may be 10 mm to 20 mm less than the diameter of
the specimen to allow the formation of a watertight seal. The surface not covered by the pond
shall be completely sealed using the sealant or the tape defined in 6.2.2.2 b).
NOTE At the edge of such specimens, there will not be unidirectional chloride ingress.
An alternative technique is to use a slightly larger tube and a rubber gasket between the tube
and the sealed side of the specimen.
2) Profile specimen for inversion:
After sealing in accordance with 6.2.2 and storage in the calcium hydroxide solution, the
specimen shall be transferred directly to the inversion exposure apparatus without surface
drying. A suitable arrangement is shown in Annex E. The volume of the exposure solution shall
not be less than 12,5 ml per square centimetre of exposed surface.
7 Procedure
7.1 Exposure conditions
7.1.1 Chloride exposure solution
Unless specified otherwise, the chloride exposure solution shall be a 3 % NaCl solution in accordance
with 5.1.2 a) If the chloride exposure solution is other than the reference solution [see 5.1.2 b)], it shall
be reported. The chloride exposure solution concentration after use shall be measured and recorded.
NOTE 1 Where testing is related to the intended use in a specific exposure condition, the chloride exposure
solution should reflect the exposure conditions taking into account the expected depletion of chloride.
NOTE 2 During the test period the concentration of the chloride exposure solution will reduce. The volume of
chloride exposure solution has been selected so that it does not have to be replaced during a test lasting 90 days.
If a longer test period is required, the chloride exposure solution should be replaced at 91 day intervals.
NOTE 3 Fick’s Law is based on the assumption that the external chloride concentration remains constant
during the duration of the test. In the normal test situation, the error introduced by assuming that the chloride
concentration remains constant at the initial concentration is small.
7.1.2 Exposure temperature
Where used, the temperature of the water bath for the immersion specimen, the temperature of the
chloride exposure solution in the inversion method and the temperature of the chamber used
...
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