EN 539-2:2006

SLOVENSKI STANDARD
01-oktober-2006
1DGRPHãþD
SIST EN 539-2:1998
2SHþQLVWUHãQLNL±8JRWDYOMDQMHIL]LNDOQLKODVWQRVWL±GHO3UHVNXãDQMH
RGSRUQRVWLSURWL]DPU]RYDQMX
Clay roofing tiles for discontinuous laying - Determination of physical characteristics -
Part 2: Test for frost resistance
Dachziegel für überdeckende Verlegung - Bestimmung der physikalischen Eigenschaften
- Teil 2: Prüfung der Frostwiderstandsfähigkeit
Tuiles de terre cuite pour pose en discontinu - Détermination des caractéristiques
physiques - Partie 2 : Essais de résistance au gel
Ta slovenski standard je istoveten z: EN 539-2:2006
ICS:
91.060.20 Strehe Roofs
91.100.25 .HUDPLþQLJUDGEHQLL]GHONL Ceramic building products
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 539-2
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2006
ICS 91.100.25 Supersedes EN 539-2:1998
English Version
Clay roofing tiles for discontinuous laying - Determination of
physical characteristics - Part 2: Test for frost resistance
Tuiles de terre cuite pour pose en discontinu - Tondachziegel für überlappende Verlegung - Bestimmung
Détermination des caractéristiques physiques - Partie 2 : der physikalischen Eigenschaften - Teil 2: Prüfung der
Essais de résistance au gel Frostwiderstandsfähigkeit
This European Standard was approved by CEN on 18 May 2006.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the Central Secretariat or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official
versions.
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. EN 539-2:2006: E
worldwide for CEN national Members.

Contents Page
Foreword.3
1 Scope .4
2 Normative references .4
3 Terms and definitions .4
4 Test pieces .7
5 Test method A.7
5.1 Principle.7
5.2 Apparatus .7
5.3 Sampling.8
5.4 Preliminary treatment.8
5.5 Procedure .9
5.6 Interpretation of the results .11
5.7 Test report .12
6 Test method B.12
6.1 Principle.12
6.2 Apparatus .13
6.3 Sampling.18
6.4 Preliminary treatment.18
6.5 Procedure .19
6.6 Evaluation of the test results.22
6.7 Test report .23
7 Test method C.24
7.1 Principle.24
7.2 Apparatus .24
7.3 Sampling.25
7.4 Preliminary treatment.25
7.5 Procedure .25
7.6 Interpretation of the test results.28
7.7 Test report .28
8 Test method D.29
8.1 Principle.29
8.2 Apparatus .29
8.3 Sampling.29
8.4 Preliminary treatment.29
8.5 Procedure .30
8.6 Interpretation of the test results.31
8.7 Test report .31
9 Test method E (European single test method) .33
9.1 Principle.33
9.2 Apparatus .34
9.3 Test sample .35
9.4 Procedure .35
9.5 Evaluation of the test pieces .40
9.6 Test report .41
Annex A (normative) Determination and calculation of water absorption .42
Annex B (normative) Determination of the dry density by hydrostatic weighing.43
Foreword
This document (EN 539-2:2006) has been prepared by Technical Committee CEN/TC 128 “Roof covering
products for discontinuous laying and products for wall cladding”, the secretariat of which is held by IBN/BIN.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by December 2006, and conflicting national standards shall be withdrawn
at the latest by December 2006.
This document supersedes EN 539-2:1998.
This part of the standard is one of a series of standards concerning clay roofing tiles, the list of which is
indicated below:
EN 1304, Clay roofing tiles and fittings — Products definitions and specifications
EN 538, Clay roofing tiles for discontinuous laying — Flexural strength test
EN 1024, Clay roofing tiles for discontinuous laying — Determination of geometric characteristics
This part of EN 539 is preceded by Part 1:
EN 539-1, Clay roofing tiles for discontinuous laying — Determination of physical characteristics — Part 1:
Impermeability test
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: 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.

1 Scope
This part of this European Standard specifies five test methods for the determination of frost resistance of clay
roofing tiles and fittings.
The first four test methods (methods A, B, C and D) are applicable according to the requirements described in
EN 1304.
The fifth test method (E) is applicable in all the CEN members in accordance with the requirement of each
member state. Each country indicates the level or levels in their national foreword of EN 539-2.
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 1304, Clay roofing tiles for discontinuous laying — Products definitions and specifications
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
pit
see definition in EN 1304
3.2
hair crack
superficial crack having a width of not more than 0,20 mm

3.3
nascent crack
crack formation at the edge, only crack penetrating slightly into the interior of the ceramic body

3.4
surface crack
crack more than 0,20 mm wide and with a length of more than 30 mm, which does not pass through the
thickness of the product
3.5
surface damage
loss of a part of the ceramic body from the surface of the product, one of the dimensions of that part being
greater than 10 mm. The surface area of the product remains unchanged

3.5.1
scaling
surface raising, nascent chipping, or crack, which initiates damage

3.5.2
chip
loss of a fraction of the body material of the product

3.5.3
peeling
loss of a part of the superficial layer of the product

3.5.4
flaking
progressive loss of body material affecting parts or the whole thickness of the product

3.6
structural crack
see definition in EN 1304
3.7
loss of ribs
loss of body material from the interlocking ribs sufficient to influence their function

3.8
break
see definition in EN 1304
3.9
delamination
lamellar flaking which can lead to the delamination of the body in a succession of parallel layers

3.10
calibration device (applies to method E only)
roof tile or ceramic slab which may be specially made to possess the characteristics defined within 9.4.1.1 and
which will not be damaged during the calibration
4 Test pieces
If the tiles or fittings are placed on the market with a ceramic coating and/or treatment, the tests shall be
carried out on test pieces having this coating and/or treatment.
When the tiles or fittings are taken from a site or building, they shall be tested in the state in which they are
found, but the interpretation of the test results shall take into account the stresses to which these installed
products have been subjected.
5 Test method A
5.1 Principle
The sample of test pieces is immersed in water under vacuum at an absolute air pressure of 4 × 10 Pa. It is
next subjected to a fixed number of freeze/thaw cycles, after which the individual test pieces are examined for
any possible damage caused by frost. The heat extraction at the exposed surface of the product creates a
unidirectional freezing flow from the exposed surface of the product towards its interior. After each freezing
stage the test pieces are completely thawed out in water. The preliminary soaking and the freeze/thaw cycles
are carried out following exact procedures.
5.2 Apparatus
5.2.1 Drying oven
It shall be adjustable to (110 ± 5) °C.
5.2.2 Balance
It shall be accurate to within 1 g.
5.2.3 Programme controlled freezing unit
Consisting of:
 exposure chamber, thermally insulated and fitted with a grid. The exposure chamber shall be able to
accommodate at least one sample;
 air circulation system allowing an even air flow to be directed towards the lower part of the exposure
chamber at a velocity of about 1,5 m/s in the section above the test pieces, so that the extraction of heat
at the surface of the test pieces corresponds to:
(300 ± 60) W/m² at (- 15 ± 3) °C and (100 ± 20) W/m² at (- 5 ± 1) °C;
 refrigeration unit, capable of reducing the air temperature in the test chamber from (18 ± 2) °C to
(- 15 ± 3) °C in 1 h 45 min ± 15 min;
 thawing system, with provision for the supply of water to and the removal of water from the exposure
chamber, as well as an overflow system and a mechanism for reheating the thawed water to (18 ± 2) °C.
This unit shall be capable of being filled with and emptied of water in a period of less than 15 min;
 control and measuring unit, capable of controlling and checking the successive freeze/thaw cycles
according to the appropriate programme. Temperature measurements shall be accurate to within 0,5 °C.
The measurement is carried out at a distance of 25 mm from the middle of the test piece in the middle of
the exposure chamber. The temperature of the test piece is measured at the centre of the gravel filler
directly beneath the test piece.
5.2.4 Miscellaneous
The following are also necessary for carrying out this test:
 material allowing the construction of a test assembly (see Figure 1) made up of two test pieces arranged
back to back at a distance of about 50 mm, as well as a gravel filler which will allow the unidirectional
freezing of the test pieces and a damp atmosphere around their back sides (e.g. gravel with a particle
size of 2 mm to 4 mm);
 absorbent cloths, waterproof ink, potable water.
5.3 Sampling
5.3.1 Laboratory sample
The laboratory sample shall be selected at random from the production or consignment concerned and shall
consist of eight whole and undamaged clay roofing test pieces (tiles or fittings).
The sampled test pieces shall conform to the requirements concerning structural characteristics laid down in
EN 1304.
5.3.2 Test sample
The test sample consists of six out of the eight test pieces referred to above.
After the soaking operation as described in 5.4.3, the three test pieces displaying the highest water absorption
are selected, as well as three other test pieces chosen at random.
These test pieces shall be marked with waterproof ink. The remaining two test pieces are kept as a reference
to use when compiling the test results.
5.4 Preliminary treatment
5.4.1 Drying of the sample
Dry the test pieces at (110 ± 5) °C for 48 h.
Weigh each test piece in its dry state to an accuracy of one gram to determine its dry mass (M ) after cooling
d
in the ambient air of the laboratory.
5.4.2 Visual inspection of the sample
Examine the dry test pieces with the naked eye and in normal daylight for possible imperfections. Mark each
imperfection with waterproof ink.
5.4.3 Soaking of the test pieces
5.4.3.1 General
The procedure for soaking in water described below is carried out before the freeze/thaw test to realize the
saturation prior to doing this test.
5.4.3.2 Principle
The water absorption takes place at absolute pressure of 4 × 10 Pa.
5.4.3.3 Apparatus
Water supply tank, filled with potable water.
Vacuum tank, easily accessible and fitted with a grid and water gauge, suitable for the soaking of at least one
test sample.
Connecting pipe with control valve, between the bottom of the water supply tank and the space below the grid
in the vacuum tank.
Vacuum pump with pressure control unit, connected with the vacuum tank above the maximum water level
and capable of reaching and maintaining an absolute air pressure of 3 × 10 Pa.
5.4.3.4 Procedure
Place the dry test pieces in a vertical and free position in the vacuum tank, with their longest edges resting on
the grid.
4 3
Evacuate the vacuum tank now filled and closed, for (60 ± 5) min at absolute pressure of (4 × 10 ± 10 ) Pa.
Introduce water from the water supply tank into the vacuum tank for (30 ± 3) min whilst maintaining the
absolute pressure, so as to immerse the test pieces gradually until the water level is 20 mm to 25 mm above
their highest point. Maintain the pressure above the immersed test pieces for another (30 ± 3) min. Then
restore atmospheric pressure in the tank.
The soaking procedure is now completed.
Remove each test piece from the water tank, wipe off the surface water with an absorbent cloth and weigh it
to the nearest gram to determine its wet mass (M ). Calculate the water content (W ) in % of the dry mass
s s
using the following equation:
W = [(M - M ) / M ] in %.
s s d d
Do not allow the test pieces to dry out whilst waiting to start the freeze/thaw test.
5.5 Procedure
5.5.1 Positioning of the test pieces
Arrange the test pieces in pairs using elastic bands or equivalent material to constitute an assembly as shown
in Figure 1, so that the test pieces are positioned back to back with a gap of approximately 50 mm between
the closest points filled with gravel (2 mm to 4 mm particle size).
Place a temperature sensor behind the test piece with the highest water content; this is simply to check the
temperature.
Place the test assemblies vertically on the grid in the exposure chamber of the freeze/thaw simulator with a
gap between them of at least 50 mm.
If necessary, fix the test assemblies to the grid to improve their stability in the submerged situation.

Key
1 gravel
2 slab of extruded foam with closed pores
3 elastic band
Figure 1 — Example of assembly with two tiles
5.5.2 Freeze/thaw programme
Submit the test sample to 24 freeze/thaw cycles, consisting of 12 cycles with an air temperature of
(- 15 ± 1) °C in the freezing stage, followed by 12 cycles with an air temperature of (- 5 ± 0,5) °C in the
freezing stage.
Immerse the test pieces in water at (18 ± 2) °C during the thawing stage.
Each freezing stage shall last for 8 h ± 6 min and each thawing phase for 4 h ± 6 min.
The freezing stage of 8 h ± 6 min includes the time necessary for lowering the temperature to and maintaining
it at (- 15 ± 3) °C.
The thawing stage of 4 h ± 6 min includes the time necessary for filling with water and draining it away.
5.5.3 Carrying out of the test
Carry out the freeze/thaw test as specified in 5.5.2 after a period of soaking in water at (18 ± 2) °C for a
minimum of 2 h and a maximum of 4 h. Commence the 24 freeze/thaw cycles with a freezing stage at an air
temperature of (- 15 ± 3) °C.
5.5.4 Assessment of possible damage caused by frost
5.5.4.1 Drying of the test pieces
After completion of the freeze/thaw test remove the test pieces from the test assemblies, rinse thoroughly in
clear water and then dry at (110 ± 5) °C for 48 h.
5.5.4.2 Final visual inspection
Examine each test piece of the sample on all its surfaces with the naked eye in normal daylight from a
distance of 250 mm to 400 mm for any visible frost damage caused during the test.
Record the nature, position and extent of any possible frost damage separately on each test piece (see
Clause 3).
5.6 Interpretation of the results
The sample shall be considered frost resistant if none of the test pieces show any of the following types of
damage constituting failure of this test:
 loss of rib(s);
 surface crack(s) or structural crack(s);
 breaks;
 scaling or surface damage;
 flaking;
 delamination;
 peeling;
1)
 each of the test pieces has kept one nib intact .
A test piece revealing a hair crack on one of its edges shall be sawn through to check on internal delamination.
For comparison, the test pieces kept in reserve (see 5.3.2) should also be sawn through. Hair cracks on the
tile edges due to internal delamination caused during the test and consequently not found in the reference test
pieces, shall be considered as frost damage constituting failure of this test.
Whatever their dimension, pits caused by the presence of concentrations of pyrites or lime, hair cracks and
nascent cracks shall not be considered as frost damage constituting failure of this test.
Equally, minor damages such as:
 scaling;
 flaking;
 peeling
are not considered as frost damage constituting failure of this test;

1)
This last specification concerns only test pieces with one or several nibs before testing.
provided that:
 damaged area is less than 200 mm²;
 mean depth is less than 2 mm with a maximum local size of 3 mm;
 damage does not relate in any way to internal delamination (to be checked by cutting through).
5.7 Test report
The test report shall include:
a) designation of the sample tested including the description and identification of the tiles or fittings including
the type, the dimensions, the name of the manufacturer, and if possible, the production date (reference to
marking and to the requirements of EN 1304);
b) number of this European Standard, i.e. EN 539-2;
c) test method used A;
d) name of the test laboratory;
e) date when the laboratory received the sample;
f) date of the test;
g) table listing for each test piece:
 initial dry mass M ;
d
 water content after soaking W ;
s
 type, position and extent of any visible frost damage appeared during the test;
h) assessment of the frost resistance of the sample according to the requirements stated in the method used
to do the test;
i) comments if necessary;
j) signature of the person in charge of the test.
6 Test method B
6.1 Principle
Natural critical freeze/thaw cycles are simulated by saturating test pieces with water and then exposing them
to severe freezing on one surface only.
The upper surfaces of suitably prepared test pieces selected according to statistical principles are directly
exposed to freezing in a programme-controlled freezing unit then thawed by sprinkling with reheated water,
followed by immersion in water. The freeze/thaw cycles are repeated until the test pieces show signs of
serious damage or until 150 freeze/thaw cycles have been completed.
6.2 Apparatus
6.2.1 Ventilated drying oven
It shall be capable of reaching a temperature of at least 120 °C.
6.2.2 Balance
It shall be accurate to within 1 g.
6.2.3 Water tank
Container, made of steel or plastic for example.
6.2.4 Sprinkling system (see Figure 2)
It consists of a sealed container equipped with an observation window.
Two rafters are arranged in the lower third of the container at an angle of 15° to the horizontal. Battens are
then fixed to the rafters in such a way that three rows of test pieces can be arranged as on a roof. The battens
shall be long enough to accommodate at least three test pieces laid side by side.
The base of the sprinkling system forms a basin for collecting water. A water atomizer is located inside the
airtight container to ensure that a relative humidity of above 95 % is maintained inside the container.
Two spray nozzles are fitted 50 cm above the surface of the test roof to spray the test pieces with water. The
combined rate of flow through both nozzles shall be 12 l/min.
Key
1 observation window
2 spray nozzle
3 water atomizer
Figure 2 — Sprinkling system
6.2.5 Programme controlled freezing unit (see Figure 3)
Dimensions in millimetres
Key
1 cooling unit
2 test specimen rack
3 cover plate (see also 6.5.2)
4 deflector plates
5 side walls
6 jets
Figure 3 — Diagrammatic representation of a programme controlled freezing unit filled with test
pieces
The programme controlled freezing unit consists of a freezing chamber, fan, cooling units, jets for sprinkling,
water level regulator, water drain and programme control unit.
It shall be large enough to accommodate a test pieces rack made of stainless steel, with cover plate and
deflector plates made of 3 mm thick, thermally-insulating plastic and trapezoidal side walls likewise made of
plastic.
The freezing unit is equipped with a lid. It shall be closed on all sides and have a sufficient effective volume of
at least 0,5 m so that it can accommodate a minimum of six test pieces placed in an upright, but inclined,
position in a row on the rack.
The fan fitted into the freezing chamber (e.g. into the lid) shall circulate air in such a way that all test piece
surfaces are fanned from above with approximately the same volume of air so as to ensure uniform heat
extraction.
Temperature sensors shall be fitted at several points inside the freezing chamber to permit monitoring of the
uniform temperature distribution inside the chamber. If necessary, deflectors can be fitted to maintain a
uniform temperature distribution.
It shall be possible to regulate the output of the cooling unit so that cooling and ice formation measured in a
reference tile is in accordance with the cooling curve shown in Figure 5.
A water jet is placed in front of each test piece so that the (visible) active surface of it can be uniformly
sprayed with water, which shall have a temperature from 5 °C to 10 °C and a flow rate of 4,5 l/min per jet.
In order to achieve a steady and reproducible sequence of the freeze/thaw cycles, the freezing unit shall be
equipped with a programme control unit allowing the cooling process with intermittent spraying and also the
thawing process to be carried out in the required time.
Key
1 cover plate
2 trapezoidal side walls
3 deflector plates
4 stainless steel support, made of rods 10 mm in diameter
Figure 4 — Test pieces rack in the freezing unit
6.2.6 Reference tile
As a reference tile, use a tile with the same average density and water absorption as the samples used for
calibrating the freezer (see 6.5.2) and a thickness of 12 mm to 14 mm. Drill a hole into this tile of 5 mm
diameter and 50 mm long, parallel to its length (so as to retain a body thickness of 3 mm to 4 mm), insert a
temperature sensor that reaches to the bottom of the hole and seal the hole with a flexible compound. When
measuring the temperature of the programme controlled freezing unit, the reference tile shall have a water
content of (8,5 ± 0,5) %.
6.2.7 Temperature measuring instruments
Use for temperature measurement thermocouples or resistance thermometers.
Use suitable recording instruments, with an error limit of 0,5 K, to register the temperature.
6.3 Sampling
6.3.1 Laboratory sample
Take 30 whole test pieces to represent the products manufactured, unless agreed otherwise.
6.3.2 Pre-selection of test pieces
Calculate the water absorption (W ), of the 30 chosen test pieces at atmospheric pressure according to the
u
requirements of Annex A.
6.3.3 Test sample
From 30 test pieces that have been pre-selected as described in 6.3.2, choose six of them as follows: take the
two test pieces with the lowest water absorption, two test pieces with mean water absorption and the two test
pieces with the highest water absorption. Use these six test pieces as described in 6.5 and prepare them in
accordance with 6.4.
Describe the initial condition of the test pieces and note any cracks and damage carefully.
6.4 Preliminary treatment
6.4.1 Drying of the sample
Dry the test pieces making up the sample as described in 6.3.3 for 24 h at (110 ± 5) °C. After cooling in the
ambient air of the laboratory, weigh each test piece with an accuracy of 1 g to determine its dry mass (m ).
tr
6.4.2 Conditioning of the test pieces in the sprinkling system
After carrying out the treatment described in 6.4.1, place the test pieces and three additional test pieces of the
same type in three rows on the battens in the sprinkling system as they would be laid on a roof. In the case of
pantiles that do not require torching and of plain tiles, the overlap shall be only 50 mm.
Arrange the six test pieces on the two lower rows and the three additional test pieces on the top row.
Leave the test pieces and the additional test pieces for 15 h to 20 h at a temperature of (20 ± 3) °C and a
relative humidity of 95 % to 100 % (storage in a damp room). Then spray this test roof with mains tap water at
a temperature of 5 °C to 10 °C for a period of 6 h.
6.4.3 Immersion of the test pieces in water
Next place the test pieces vertically upright on one long edge in the mains tap water so that the water level is
at least 50 mm above the test pieces. Leave the test pieces like this for 15 h to 18 h.
6.4.4 Determination of water absorption
Wipe each test piece with a damp sponge and weigh it to determine its wet mass (m ).
w
, R), for each test piece as a percentage of the dry mass from the following
Calculate the water absorption (W
u
equation:
W , R = [(m - m ) × 100/m ] in %.
u w tr tr
6.5 Procedure
6.5.1 Automatic control of the freezing unit
6.5.1.1 General
There are two fundamentally different methods for setting up the automatic cooling system so that a constant
and reproducible level of refrigeration is obtained.
6.5.1.2 Automatic control according to procedure no.1
The thermal variables are held constant for the different tests. This means that the freezing unit is loaded with
a constant mass of test pieces and a constant weight of water absorbed by the test pieces.
Any deficiency in mass shall be made up by the addition of dummy tiles and the effectiveness of the cooling
system shall be kept approximately constant.
The holding period of (35 ± 3) min at 0 °C shall be adjusted using a set of reference tiles.
The adjustment made with the reference tiles shall be retained for all further tests.
If, during further tests, the mass of the test pieces and their water content varies significantly from that of the
set of reference tiles, the differences shall be corrected, either by reducing the number of test pieces or by
using extra dummy tiles.
Items containing water, such as wet sponges in plastic bags, can be used to adjust the water content.
If the above procedure is followed, an air temperature curve can be obtained that will be reproduced for all of
the tests.
6.5.1.3 Automatic control according to procedure no.2
In this procedure, the air temperature change is regulated.
The air temperature curve which is determined once for all the tests with a set of reference tiles is reproduced
for any further tests.
The development of the predetermined temperature curve depends on the resistance to heat transmission
between the air and the measured tile and thus on the air flow speed and shall be determined for each
freezing unit separately.
Control according to procedure no.2 is more demanding than control according to procedure no.1 with regard
to the amount of adjustment necessary; however, it enables reproducible conditions to be obtained without
recourse to dummy tiles or damp sponges.
6.5.2 Calibration of the freezing unit
To calibrate the freezing unit use a set of six reference tiles placed in a frame as shown in Figure 3.
Use as reference tiles overlapping tiles having a body thickness from 11 mm to 14 mm and a density of
(2 ± 0,5) kg/dm . Determine the density by weighing under water as described in Annex B. Determine the
water absorption under ambient pressure according to Annex A.
Place in the set the reference tile with a temperature sensor as described in 6.2.6 to measure the temperature
of the tile.
When control procedure no.1 is used, the total mass of the test assembly shall be the same as that used to
establish the control procedure.
When following control according to procedure no.2, as well as the set of reference tiles, other test pieces can
be selected arbitrarily.
However, all the frames in the test unit shall be filled with tiles as shown in Figure 3, so that a uniform air flow
is guaranteed.
During calibration, the output of the cooling units shall be adjusted until the temperature of the reference tile
changes in compliance with the cooling curve shown in Figure 5.
The air temperature in the freezing chamber shall fall to the minimum temperature as shown in Figure 5.
Fluctuations in the mean tile temperature are permissible, provided that they do not exceed the limit curves
shown. A variation of 2 K is permitted in the air temperature during the period of ice formation.
Take care that ice forms evenly over a period of (35 ± 3) min, the variation of temperature being limited to 1 K
above and 2 K below the mean temperature.
When calibrating the freezing unit and adjusting the cooling units, place the reference tile in the middle of the
other tiles.
Air distribution and cooling inside the freezing unit (see 6.2.5) shall be such that subsequent check cycles
demonstrate that the curve shown in Figure 5 is maintained, regardless of where the reference tile is placed in
the set, and particularly when it is placed at one side.
Use the calibrated freezing unit for all the tests described below.
In the case of control according to procedure no.1, if deviations are detected e.g. by recording the air
temperature variations, readjust the output of the cooling units with a new sample set and reference tiles as
described above.
6.5.3 Placing test pieces in the freezing unit
Immediately after the wet mass has been determined as specified in 6.4.4, place the six test pieces in the
freezing unit as shown in Figure 3, in two rows on a rack as shown in Figure 4, so that they are positioned with
their lower surfaces facing towards the inside. Depending on the type of tile, three specimens shall be placed
edge-to-edge, overlapping or interlocking.
If the mass of the test pieces including their water content differs from that of the reference set, and if this
affects the cooling characteristic of the freezer (i.e. produces deviations from the curve shown in Figure 5),
compensate for the differences in mass either by reducing the number of test pieces or by adding whole or
parts of dummy tiles. Water impregnated items, such as wet sponges in plastic bags shall be used if
necessary to compensate for the water content.
Arrange the cover plate to fit as closely to the upper edges of the test pieces as possible. Fill the spaces
between the long edges of the outer trapezoidal test pieces and the sides of the rack with fitted pieces of
plastic, so that a closed arrangement is produced, this having only a narrow space of 15 mm between the
deflector plates (see Figure 4). This arrangement ensures that the temperature on the undersides of the
specimens decreases more slowly than on the upper sides.
6.5.4 Freezing of test pieces (see also Figure 5)
To prevent drying out of the test pieces during freezing, spray the surface of each one with water for 5 s
at 5 min intervals, the flow rate of each jet being 4,5 l/min. Continue spraying until the air temperature reaches
approximately 0 °C.
Maintain the minimum temperature of (- 15 ± 2) °C until the temperature of the reference tile has remained
at (- 15 ± 2) °C for at least 30 min.
6.5.5 Thawing of test pieces
After freezing, thaw the test pieces by uniformly spraying their visible surfaces with water at a temperature
from 5 °C to 10 °C.
Adjust the volume of water so that the test pieces are under a water level of about 50 mm after 15 min, the
minimum volume of water being 8,5 l per kg of test pieces.
Leave the test pieces in the water for at least a further 15 min, after the ice has completely melted.
Drain off the water after the test pieces have been thawed and commence the next freezing cycle.
6.5.6 Number of freeze/thaw cycles
Carry out 150 freeze/thaw cycles, if possible without interruption. If this happens, leave the test pieces in the
water. If the interruption exceeds two hours, restart the process with a thawing phase as described in 6.5.5
before carrying out a new freezing cycle.
Key
Y axis: temperature °C
X axis: time min
1 holding temperature
2 limit curves
3 air temperature
4 period of ice formation
Figure 5 — Cooling curve (with permissible deviation) for reference tile
6.5.7 Examination of the test pieces
After each period of 50 cycles and upon completion of the test examine the test pieces with the naked eye at a
distance of 30 cm to 40 cm, under normal lighting, for any possible damage.
Note the type, position and extent of any damage that has appeared after a given number of cycles, using the
definitions given in Clause 3.
6.6 Evaluation of the test results
The sample will have passed the test, if after 150 freeze/thaw cycles, none of the test pieces show any
damage as described as unacceptable according to Table 1.
Table 1 – List of damages
a
Fault
u l
1 pit
- -
2 hair crack - -
3 nascent crack - -
b
4 surface crack x
-
b
5 scaling x
-
b
6 peeling x
-
b
7 surface damage x
-
8 structural crack x x
9 break x x
10 delamination x x
a
u = upper surface of tile l = lower surface of tile x = unacceptable - = acceptable
b
On the lower surface of the tile this irregularity constitutes damage, if the function of the tile itself or
of the ribs is impaired.
According to the test method B, frost damage constituting failure of this test is damage on the exposed face of
a tile, clearly visible to the naked eye, such as surface cracks, scaling and surface damage. Nibs and
interlocking ribs on the lower surfaces shall be checked to see whether they have retained their form and
function. If the tiles have been designed in such a way that they have one or several nibs, at least one nib
shall be undamaged after the frost.
Surface damage due to air entrainment and clay folds near the interlocks are not regarded as frost damage,
nor shall pits, whatever their dimension, due to the expansion of granular inclusions (e.g. of lime) as a result of
chemical processes.
6.7 Test report
The test report shall include:
a) designation of the sample tested including the description and identification of the tiles or fittings including
the type, the dimensions, the name of the manufacturer, and if possible, the production date (reference to
marking and to the specifications of EN 1304);
b) number of this European Standard, i.e. EN 539-2;
c) test method used B;
d) name of the test laboratory;
e) date when the laboratory received the sample;
f) date of the test;
g) for each of the 30 test pieces of the laboratory sample and for each of the six test pieces for the test
sample a table stating:
 initial dry mass m ,
tr
 wet mass m , m , m ,
w n u
 water content after soaking W , W , R
u u
and, only for each of the six test pieces:
 number of freeze/thaw cycles carried out;
 type and extent of any frost damage with an indication of the number of cycles carried out before the
damage became apparent and after completion of the freeze/thaw test;
h) assessment of the frost resistance of the sample according to the requirements stated in the method used
to do the test;
i) comments if necessary;
j) the signature of the person in charge of the test.
7 Test method C
7.1 Principle
Test pieces are immersed in water under a vacuum and then placed in a refrigerator where they are subjected
to 50 freeze/thaw cycles; the products are frozen on all their surfaces at the same time.
7.2 Apparatus
7.2.1 Ventilated drying oven
It shall make it possible to reach a temperature of at least
...