SIST-TP CEN/TR 15177:2006
(Main)Testing the freeze-thaw resistance of concrete - Internal structural damage
Testing the freeze-thaw resistance of concrete - Internal structural damage
This document specifies three test methods for the estimation of the freeze-thaw resistance of concrete with regard to internal structural damage. It can be used either to compare new constituents or new concrete compositions against a constituent or a concrete composition that is known to give adequate performance in the local environment or to assess the test results against some absolute numerical values based on local experiences.
Extrapolation of test results to assess different concrete i.e. new constituents or new concrete compositions requires an expert evaluation.
NOTE Specification based on these test methods should take into account the behaviour of concrete under practical conditions.
There is no established correlation between the results obtained by the three test methods. All tests will clearly identify poor and good behaviour, but they differ in their assessment of marginal behaviour.
Prüfung des Frost-Tauwiderstandes von Beton - Innere Gefügestörung
Dieses Dokument beschreibt drei Prüfverfahren zur Abschätzung des Frost-Tauwiderstandes von Beton hinsichtlich der inneren Gefügestörung. Es kann angewendet werden, um neue Ausgangsstoffe oder neue Betonzusammensetzungen mit bekannten Ausgangsstoffen oder Betonzusammensetzungen, mit denen in der örtlichen Umgebung ein ausreichendes Verhalten sichergestellt wird, zu vergleichen oder um die Prüfergebnisse mit Grenzwerten, die auf örtlichen Erfahrungen basieren, zu vergleichen und zu bewerten.
Die Extrapolation der Prüfergebnisse zur Bewertung verschiedener Betonarten, d.h. mit neuen Bestandteilen oder mit einer neuen Zusammensetzung, ist von einem Fachmann zu bewerten.
ANMERKUNG Die Festlegung von Beton auf der Grundlage dieser drei Prüfverfahren sollte das Verhalten des Betons unter praktischen Bedingungen berücksichtigen.
Es gibt keine feststehende Korrelation zwischen den Ergebnissen aus den drei Prüfverfahren. Alle Prüfverfahren ermöglichen die deutliche Unterscheidung zwischen schlechtem und gutem Verhalten. Sie unterscheiden sich jedoch in der Bewertung des Verhaltens in Grenzfällen.
Preskušanje odpornosti betona proti zmrzovanju/tajanju – Notranje poškodbe strukture
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST-TP CEN/TR 15177:2006
01-september-2006
Preskušanje odpornosti betona proti zmrzovanju/tajanju – Notranje poškodbe
strukture
Testing the freeze-thaw resistance of concrete - Internal structural damage
Prüfung des Frost-Tauwiderstandes von Beton - Innere Gefügestörung
Ta slovenski standard je istoveten z: CEN/TR 15177:2006
ICS:
91.080.40 Betonske konstrukcije Concrete structures
91.100.30 Beton in betonski izdelki Concrete and concrete
products
SIST-TP CEN/TR 15177:2006 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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TECHNICAL REPORT
CEN/TR 15177
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
April 2006
ICS 91.080.40
English Version
Testing the freeze-thaw resistance of concrete - Internal
structural damage
Prüfung des Frost-Tauwiderstandes von Beton - Innere
Gefügestörung
This Technical Report was approved by CEN on 31 August 2005. It has been drawn up by the Technical Committee CEN/TC 51.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,
Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2006 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 15177:2006: E
worldwide for CEN national Members.
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CEN/TR 15177:2006 (E)
Contents Page
Foreword.3
Introduction .4
1 Scope .5
2 Normative references .5
3 Terms and definitions .5
4 Equipment .6
5 Making of test specimens .9
6 Principle of measurement the internal structural damage.10
7 Beam test.11
8 Slab test .16
9 CIF-test.24
Bibliography .34
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CEN/TR 15177:2006 (E)
Foreword
This document (CEN/TR 15177:2006) has been prepared jointly by Technical Committee CEN/TC 51
"Cement and building limes", the secretariat of which is held by IBN/BIN and by Technical Committee CEN/TC
104 "Concrete and related products", the secretariat of which is held by DIN.
No existing European Standard is superseded.
It is based on the Austrian Standard ÖNORM B 3303 "Testing of Concrete" and on the RILEM
recommendation "Test methods of frost resistance of concrete" of RILEM TC 176 IDC. These tests have since
been developed by individual countries. This document takes into account those developments.
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CEN/TR 15177:2006 (E)
Introduction
Concrete structures exposed to the effects of freezing and thawing need to be durable, to have an adequate
resistance to this action and, in cases such as road construction, to freezing and thawing in the presence of
de-icing agents. It is desirable, especially in the case of new constituents or new concrete compositions, to
test for such properties. This also applies to concrete mixes, concrete products, precast concrete, concrete
elements or concrete in situ.
Many different test methods have been developed. No single test method can completely reproduce the
conditions in the field in all individual cases. Nevertheless, any method should at least correlate to the
practical situation and give consistent results. Such a test method may not be suitable for deciding whether
the resistance is adequate in a specific instance but will provide data of the resistance of the concrete to
freeze-thaw-attack and freeze-thaw-attack in the presence of de-icing agents.
If the concrete has inadequate resistance there are two types of concrete deterioration when a freeze-thaw
attack occurs, internal structural damage and scaling. The three test methods in this document describe the
testing for internal structural damage. The scaling is dealt with in prCEN/TS 12390-9.
This document contains three different test methods, which are well proved in different parts of Europe.
Always they produce consistent results. For that reason no single test method can be established as
reference test method. In the case that two laboratories will test the same concrete, they have to agree to only
one test method with the same measurement procedure.
The application of limiting values will require the establishment of the correlation between laboratory results
and field experience. Due to the nature of the freeze-thaw action, such correlation would have to be
established in accordance with local conditions and still have to be done.
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CEN/TR 15177:2006 (E)
1 Scope
This document specifies three test methods for the estimation of the freeze-thaw resistance of concrete with
regard to internal structural damage. It can be used either to compare new constituents or new concrete
compositions against a constituent or a concrete composition that is known to give adequate performance in
the local environment or to assess the test results against some absolute numerical values based on local
experiences.
Extrapolation of test results to assess different concrete i.e. new constituents or new concrete compositions
requires an expert evaluation.
NOTE Specification based on these test methods should take into account the behaviour of concrete under practical
conditions.
There is no established correlation between the results obtained by the three test methods. All tests will
clearly identify poor and good behaviour, but they differ in their assessment of marginal behaviour.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
EN 206-1, Concrete – Part 1: Specification, performance, production and conformity
EN 12390-1, Testing hardened concrete – Part 1: Shape, dimensions and other requirements of specimens
and moulds
EN 12390-2, Testing hardened concrete – Part 2: Making and curing specimens for strength tests
EN 12504-4, Testing concrete – Determination of ultrasonic pulse velocity
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
freeze-thaw resistance
resistance against alternating freezing and thawing in the presence of water alone
3.2
freeze-thaw resistance with de-icing salt
resistance against alternating freezing and thawing in the presence of de-icing salt
3.3
scaling
loss of material at the surface of concrete due to freeze-thaw attack
3.4
internal structural damage
cracks developed inside concrete which may not be seen on the surface, but which lead to an alteration of
concrete properties, e.g. reduction of the dynamic modulus of elasticity
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CEN/TR 15177:2006 (E)
4 Equipment
4.1 General
4.1.1 Equipment for making concrete specimens according to EN 12390-2.
4.1.2 Moulds for making concrete specimens according to EN 12390-1.
4.1.3 Freezing medium, consisting of de-ionised water and in special cases of 97 % by mass of tap water
and 3 % by mass of NaCl (for test with de-icing salt).
4.1.4 A freezing chamber or a freeze-thaw chest with a cooling liquid or a flooding device. The freezing
chamber or the freeze-thaw chest are equipped with a temperature and time controlled refrigerating and
heating system with a capacity such that the time-temperature curve prescribed in Clauses 7, 8 and 9 can be
followed. An automatically controllable frost chest and a water tank with thermostatic control can also be used
instead of an automatically controlled freeze-thaw chest with a flooding device.
4.1.5 Thermocouples, or an equivalent temperature measuring device, for measuring the temperature at the
appropriate prescribed points in the freezing chest with an accuracy within ± 0,5 K.
4.1.6 2 balances, with an accuracy within ± 1 g and ± 0,05 g.
4.1.7 Vernier callipers, with an accuracy within ± 0,1 mm.
4.1.8 Absorbent laboratory towel.
4.2 Special equipment for beam test
4.2.1 Thermometric frost resistance reference beam according to EN 206-1 with a dimension of 400 mm x
100 mm x 100 mm. A tolerance in length of ≤ 10 % will be permissible. A thermocouple (4.1.5) is installed
near the geometric centre of the thermometric reference beam in order to measure the temperature variations
during freeze-thaw cycles.
4.2.2 Equipment for ultrasonic pulse transit time (UPTT)
Ultrasonic pulse transit time (UPTT) measurement device which is suitable for determining the transit times of
longitudinal waves in porous building materials according to EN 12504-4. The transducers operate in
frequency range between 50 kHz and 150 kHz.
4.2.3 Equipment for fundamental transverse frequency (FF)
a) Equipment for measurement the resonance frequency: a Fourier analyser, a modally tuned impact
hammer and an accelerometer.
b) Specimens pad consists of a soft and absorbing material (e.g. foam or sponge rubber) to store the
specimens planar. The specimens pad uncoupled the specimen of its surroundings, so that the waves run
only by the specimen.
4.3 Special equipment for slab test
4.3.1 Climate controlled room or chamber with a temperature of (20 ± 2) °C and an evaporation of
(45 ± 15) g/(m² h). Normally this is obtained with a wind velocity ≤ 0,1 m/s and a relative humidity of (65 ± 5) %.
The evaporation is measured from a bowl with a depth of approximately 40 mm and a cross section area of
2
(225 ± 25) cm . The bowl is filled up to (10 ± 1) mm from the brim.
4.3.2 Diamond saw for concrete cutting.
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CEN/TR 15177:2006 (E)
4.3.3 Rubber sheet, (3 ± 0,5) mm thick which is resistant to the freezing medium used and sufficiently
elastic down to a temperature of – 27 °C.
4.3.4 Adhesive for gluing the rubber sheet to the concrete specimen. The adhesive is resistant to the
environment in question.
NOTE Contact adhesive has proved to be suitable.
3
4.3.5 Expanded Polystyrene cellular plastic, (20 ± 1) mm thick with a density of (18 ± 2) kg/m or alternative
thermal insulation with at least a heat conductivity of 0,036 W/(m⋅K).
4.3.6 Polyethylene sheet, 0,1 mm to 0,2 mm thick.
4.3.7 Equipment for length change (reference measuring procedure)
a) Length extensometer for measuring length change of specimens with a dial gauge to read in 0,01 mm
and an accuracy within ± 0,001 mm. The extensometer is designed to accommodate the size of the
specimens.
NOTE In consideration of specimens geometry the dimension of a suitable length extensometer is 170 mm or more.
b) Studs made of stainless steel or other corrosion-resistant materials being designed which secured a good
contact with the specimen surface.
c) Invar or an equivalent reverence bar with a length which is comparable to the average specimen length.
4.3.8 Equipment for ultrasonic pulse transit time (alternative measuring procedure)
Ultrasonic pulse transit time (UPTT) measurement device which is suitable for determining the transit times of
longitudinal waves in porous building materials according to EN 12504-4. The transducers operate in
frequency range between 50 kHz and 150 kHz.
4.3.9 Equipment for fundamental transverse frequency (alternative measuring procedure)
a) Equipment for measurement the resonance frequency: a Fourier analyser, a modally tuned impact
hammer and an accelerometer.
b) Specimens pad consists of a soft and absorbing material (e.g. foam or sponge rubber) to store the
specimens planar. The specimens pad uncoupled the specimen of its surroundings, so that the waves run
only by the specimen.
4.4 Special equipment for CIF-test
4.4.1 PTFE plate (Polytetrafluorethylene) or other materials with an equivalent hydrophobic surface serving
as mould for the test surface. The geometry of the plate is adapted to the 150 mm cube mould and the
thickness has to be less than 5 mm.
4.4.2 Climate controlled room or chamber with a temperature of (20 ± 2) °C and an evaporation of
(45 ± 15) g/(m² h). Normally this is obtained with a wind velocity ≤ 0,1 m/s and a relative humidity of (65 ± 5) %.
The evaporation is measured from a bowl with a depth of approximately 40 mm and a cross section area of
2
(225 ± 25) cm . The bowl is filled up to (10 ± 1) mm from the brim.
4.4.3 Lateral sealing consists of solvent-free epoxy resin or aluminium foil with butyl rubber, durable to
temperatures of - 20 °C and resistant against the attack of the de-icing solution.
4.4.4 Test containers. The specimens are stored in stainless steel containers during the freeze-thaw cycles.
The stainless sheet metal is (0,7 ± 0,01) mm thick. The size of the test container is selected in such a way that
7
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CEN/TR 15177:2006 (E)
the thickness of the air layer between the vertical side of the specimen and the test container is restricted to
(30 ± 20) mm.
Other containers can be used for capillary suction if they assure an equivalent arrangement. During the
capillary suction the test container is closed with a cover. The cover has an incline to prevent any possible
condensation water from dripping onto the specimens.
4.4.5 Spacer (5 ± 0,1) mm high placed on the container bottom to support the specimen and to guarantee a
defined thickness of the liquid layer between the test surface and the container bottom.
4.4.6 Unit for adjusting liquid level, i.e. a suction device. The suction device may consist of a capillary tube
with a spacer of (10 ± 1) mm that is connected with e.g. a water jet pump to suck up the excessive liquid in the
test containers.
4.4.7 Ultrasonic bath. The size of the ultrasonic bath is sufficiently large. The test container does not have a
mechanical contact to the ultrasonic bath. The minimum distance between the test container and the lower
surface of the bath amounts to 15 mm. The bath should provide the following power data: ERS power in the
range of 180 W to 250 W; HF peak power under double half-wave operation in the range of 360 W to 500 W;
frequency in the range of 35 kHz to 41 kHz.
4.4.8 Equipment for ultrasonic pulse transit time (reference measuring procedure)
a) Ultrasonic pulse transit time (UPTT) measurement device which is suitable for determining the transit
times of longitudinal waves in porous building materials according to EN 12504-4. The transducers
operate in frequency range between 50 kHz and 150 kHz.
b) A rectangular measuring container (e.g. PMMA) is used for UPTT measurement. The transducers are
mounted in recesses in two opposite faces of the container so that the transit axes lies parallel to and at a
distance of (35 ± 1) mm from the test surface. The size of the container is so large that the total thickness
of the coupling medium (l + l see Figure 13) is approximately 10 mm.
c1 c2
c) A stainless steel plate for collecting scaled particles of the specimens during the measurement of the
UPTT. The size of the steel plate is sufficient large and the edges are bent up approximately 5 mm to
ensure that all scaled particles can be collected.
4.4.9 Equipment for fundamental transverse frequency (alternative measuring procedure)
a) Equipment for measurement the resonance frequency: a Fourier analyser, a modally tuned impact
hammer and an accelerometer.
b) Specimens pad consists of a soft and absorbing material (e.g. foam or sponge rubber) to store the
specimens planar. The specimens pad uncoupled the specimen of its surroundings, so that the waves run
only by the specimen.
4.4.10 Equipment for length change (alternative measuring procedure)
a) Length extensometer for measuring length change of specimens with a dial gauge to read in 0,01 mm
and an accuracy within ± 0,001 mm. The extensometer is designed to accommodate the size of the
specimens.
b) Studs made of stainless steel or other corrosion-resistant materials being designed which secured a good
contact with the specimen surface.
c) Invar or an equivalent reverence bar with a length which is comparable to the average specimen length.
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CEN/TR 15177:2006 (E)
5 Making of test specimens
Except where details are specified in Clauses 7, 8 and 9 the test specimens, cubes or beams, have to be
prepared in accordance with EN 12390-2.
The inner surfaces of the moulds are lightly greased with mould oil and wiped with an absorbent towel (4.1.8)
immediately before filling so that the test results are not affected by a thick layer of mould oil.
Concrete that requires vibrating for compaction is compacted on a vibrating table.
The prestorage conditions concerning temperature and moisture are documented.
The maximum aggregate size Dmax is restricted to one third of the mould length.
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CEN/TR 15177:2006 (E)
6 Principle of measurement the internal structural damage
6.1 Relative dynamic modulus of elasticity
Generally the dynamic modulus of elasticity is defined according to Equation 1.
2 2
Equation 1: E = (X) × l ×ρ× C
dyn
where
E is the dynamic modulus of elasticity in kN/mm²;
dyn
X is the measured value;
- fundamental transverse frequency: natural frequency in Hz;
- ultrasonic pulse transit time: reciprocal of the ultra sonic pulse transit time in µs;
l is the length of the specimen in mm;
ρ is the density in kg/m³;
C is a correction factor contains the Poisson’s ratio µ.
The value of the internal structural damage is calculated as relative dynamic modulus of elasticity (RDM). For
this reason the specimens length l, the density ρ and the correction factor C can be neglected so that the
RDM is calculated according to Equation 2.
UPTT
2
X
n
Equation 2: RDM = ×100 [%]
n
X
0
where
RDM is the relative dynamic modulus of elasticity in %;
index n characterise the measure after a number of freeze-thaw cycles;
index 0 characterise the initial measure.
6.2 Length change
The internal structural damage due to repeated freeze-thaw cycles can be proofed by measuring the length
change. The relative length change is the change in length after n freeze-thaw cycles based on the initial
length according to Equation 3.
∆l
Equation 3: ε = ×100 [%]
n
l
0
where
ε is the dilation of the specimen after n freeze-thaw cycles in %;
n
∆l is the change in length after n freeze-thaw cycles in mm;
l is the initial length in mm.
0
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CEN/TR 15177:2006 (E)
7 Beam test
7.1 Principle
Beams with a dimension of 400 mm x 100 mm x 100 mm and a tolerance in length of ≤ 10 % are subjected to
freeze-thaw attack in presence of de-ionised water. The freeze-thaw resistance is measured either as relative
dynamic modulus of elasticity by using ultrasonic pulse transit time or as fundamental transverse frequency
respectively after 56 freeze-thaw cycles.
7.2 Preparation of test specimens
The test requires at least three beams.
During the first day after casting the specimens are stored in the moulds at a temperature of (20 ± 2) °C and a
relative humidity of (95 ± 5) %. The specimens are removed from the moulds after (24 ± 2) h. Directly after
demoulding, the specimens are weighed. The mass is rounded to the nearest 1 g. Following they are wrapped
in plastic film (without any additional water) so that they are substantially moisture-tight and stored for six days
in atmospheric air at (20 ± 2) °C. When the specimens are 7 d old, they are removed from the plastic film and
weighed. The mass is rounded to the nearest 1 g. Without delay the specimens are placed in a water bath
having a temperature of (20 ± 2) °C. They are stored for 21 d under water until the selected freeze-thaw test
starts.
l/2 l/2
2 1
50
2
50
3
4
Key
1 specimen
2 spots for measuring UPTT
3 spots for measuring FF
4 specimens pad (4.2.3 b)
Figure 1 - Location of the spots for measuring the ultrasonic pulse transit time
Analogues to the chosen measurement procedure the spots which are used to determine the ultrasonic pulse
transit time or the fundamental transverse frequency are marked on the specimen surface in the middle of the
fronts as shown in Figure 1. The spots are used for each measuring occasion.
7.3 Measurement procedure
7.3.1 Fundamental transverse frequency (FF)
The equipment is calibrated according to the instruction manual.
11
50 50
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3
l/2 l/2
1
2 2
5
4
Key
1 specimen
2 ultrasonic pulse transducer
3 modally tuned impact hammer
4 specimens pad (4.2.3 b)
5 accelerometer
Figure 2 - Measurement set-up for determination the internal structural damage
The specimen is placed on a thick pad (4.2.3 b). The accelerometer is hold by hand or by another suitable
means, such as a rubber band, in good contact to the concrete test surface. The specimen is taped with a
suitable tool (preferably a instrumented hammer) and the fundamental transverse frequency is recorded by
the nearest 10 Hz. The tapping is repeated at least three times to obtain an average value with a standard
deviation less than 100 Hz.
The relative dynamic modulus of elasticity RDM after n freeze-thaw cycles is calculated in percentage
FF
according to Equation 4.
2
f
n
Equation 4: RDM = ×100 [%]
FF,n
f
0
where
RDM is the relative dynamic modulus of elasticity in % determined by using FF;
FF
f is the fundamental frequency measured after n freeze-thaw cycles in Hz;
n
f is the initial fundamental frequency in Hz;
0
7.3.2 Ultrasonic pulse transit time (UPTT).
The ultrasonic equipment is calibrated according to the instruction manual.
A little amount of sonic grease is applied to the contact surface of the transducers and the marked points of
the specimens. In each case the transducers are arranged on the two opposite marked points of the
specimens as shown in Figure 2.
The transducers are pressed against the concrete surfaces so that a constant minimum value is reached. The
transmission time is read with an accuracy of 0,1 µs. It is required that the transducers are squeezed to the
concrete surface with the same pressure for each measuring occasion.
The relative dynamic modulus of elasticity RDM is calculated in percentage according to Equation 5.
UPPT
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CEN/TR 15177:2006 (E)
2
t
S,0
Equation 5: RDM = ×100 [%]
UPTT,n
t
S,n
where
RDM is the relative dynamic modulus of elasticity after n freeze-thaw cycles in %;
UPTT
t is the initial ultrasonic pulse transit time through the specimen in µs;
S,0
t is the ultrasonic pulse transit time through the specimen after n freeze-thaw cycles in µs.
S,n
7.4 Test procedure
The freeze-thaw test starts after 28 d. The specimens are removed from the water bath and their surfaces are
dried with an absorbent towel (4.1.8). The weight of each specimen is measured and rounded to the nearest 1
g.
The initial value for the measurement of the internal structural damage is determined for each specimen
according to 7.3. Immediately after this measurement the specimens are placed vertically in the freeze-thaw
chest. The freeze-thaw cycles begin 2 h at the latest after the concrete prisms are removed from water
storage.
The temperature of the freeze-thaw chest is controlled so that the temperature in the centre of the concrete
prism corresponds substantially to the temperature range in Figure 3. The temperature shall not deviate from
the shaded area in the diagram by more than 1 K for any specimen whereas the temperature difference
between 2 beams shall be ≤ 1 K. The temperature pattern of each cycle differs from that of the first cycle by
less than ± 1 K. The air temperature in the freeze-thaw chest shall not fall below – 25 °C. The break points of
the shaded area in Figure 3 are listed in Table 1.
Once a week the prisms are turned through 180° so that the former top surface of the prism is placed on the
floor of the chest. The prisms shall also be placed in different positions in the chest in accordance with some
appropriate cyclic positioning plan. The distances of the concrete prisms from one another and from the wall
are at least 60 mm.
NOTE The number of specimens in the freezing chamber or frost chest is always the same. If only few specimens are
to be tested, the empty places in the freezer are filled with blanks, unless it has been shown that the correct temperature
cycle is achieved without this precaution.
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CEN/TR 15177:2006 (E)
Key
1 freeze-thaw cycle
2 temperature range in the reference prism (7.2.1)
Y temperature in ºC
X time in h
Figure 3 - Time-temperature curve in the centre of the concrete prism
Immediately after the 8 h freezing phase the freeze-thaw chest is flooded with water at (13 ± 8) °C within a
maximum time span of 15 min, or else the concrete prisms are placed in a water bath at
(13 ± 8) °C in which the surface of the water covers the concrete prisms by at least 15 mm. The thawing
phase lasts a total of 4 h. The water is kept in motion for the entire time and is heated or cooled so that for the
entire thawing period the water temperature is (13 ± 8) °C in all parts of the freeze-thaw chest or the water
tank. 15 min before the end of the 4 h thawing phase the water is pumped out of the freeze-thaw plant in a
maximum time of 15 min. If a water bath is used the specimens are taken out of the water bath.
Table 1 - Points specifying the shaded area in Figure 3
time in h Temperature in °C
upper limit lower limit
0 + 22 + 4
2 + 2 - 2
4 - 8 - 12
6 - 16 - 20
7 - 18 - 22
8 - 18 - 22
9 + 20 + 1
12 + 22 + 4
The temperature in the centre of the reference prism, and the air and water temperatures, are measured and
recorded during a freeze-thaw cycle before the first use of the freeze-thaw chest or the frost chest and water
tank, and after about every 56 freeze-thaw cycles.
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If, in exceptional cases, it is necessary to interrupt the freeze-thaw cycles during the night and/or at weekends
(e.g. with non-automatic test equipment) the specimens are stored under freezing conditions at (- 20 ± 2) °C
during this period.
After (7 ± 1), (14 ± 1), (28 ± 1), (42 ± 1) and 56 cycles, the following procedure is carried out for each
specimen (1 ± 1) h before the start of the next freeze-thaw cycle.
a) The prisms are removed from the water bath and the surfaces dried with an absorbent towel (4.1.8).
During the period when the samples are out of the water bath and are not being tested they are covered
with moist towels. The weight of the specimens is determined with an accuracy of 1 g.
b) Depending on which measurement procedure has been used for determining the initial values for the
internal structural damage the ultrasonic pulse transit time or the fundamental transverse frequency of the
specimens is measured according to 7.3.
The specimens are returned vertically to the freeze-thaw plant.
7.5 Expression of results
Depending on which measurement procedure has been used the value of the internal structural damage is
calculated as relative dynamic modulus of elasticity RDM after n freeze-thaw cycles in percentage for each
measurement and each specimen. The RDM is rounded to the nearest 1 %.
The mean value, the individual values for each specimen as well as the standard deviation after 56 cycles are
used for evaluating the freeze-thaw resistance.
NOTE The water uptake is a good additional information to evaluate the internal structural damage. The water uptake
is calculated as change in mass ∆m after n freeze-thaw cycles in percentage according to Equation 6.
...
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