ISO 12856-1:2014

INTERNATIONAL ISO
STANDARD 12856-1
First edition
2014-03-15
Plastics — Plastic railway sleepers for
railway applications (railroad ties) —
Part 1:
Material characteristics
Plastiques — Traverses en plastique pour les applications ferroviaires
(traverses de voie ferrée) —
Partie 1: Propriétés des matériaux
Reference number
©
ISO 2014
© ISO 2014
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ii © ISO 2014 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Characteristics . 2
3.1 Material identification . 2
3.2 Chemical resistance . 2
3.3 Physical, mechanical, and electrical characteristics . 2
3.4 Weathering resistance . 3
4 Test methods . 3
4.1 General . 3
4.2 Bending strength and flexural modulus . 4
4.3 Longitudinal compressive strength . 4
4.4 Lateral compressive strength . 4
4.5 Shear strength . 5
4.6 Adhesive shear strength . 7
4.7 Alternating-current breakdown voltage . 9
4.8 Direct-current insulation resistance .11
4.9 Water absorption .14
4.10 Mass density .14
4.11 Linear expansion coefficient .14
4.12 Flame resistance .15
4.13 Weathering resistance .15
4.14 Sleeper dimensions .17
5 Inspection .18
Annex A (normative) Methodology for assessing material ageing .19
Annex B (informative) Examples of typical sleepers .26
Bibliography .29
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 (see 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 (see 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.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 61, Plastics, Subcommittee SC 11, Products.
ISO 12856 consists of the following parts, under the general title Plastics — Plastic railway sleepers for
railway applications (railroad ties):
— Part 1: Material characteristics
The following parts are planned:
— Part 2: Products
iv © ISO 2014 – All rights reserved

Introduction
Railway sleepers are manufactured mainly of pre-stressed concrete, wood, or steel. However, based on
the development of plastic materials, some plastic sleepers have been installed in recent years.
In view of the facts that the types of plastics and manufacturing processes can have various effects on
the in-service performance, this part of ISO 12856 covers the general characteristics of materials which
plastic/composite sleepers are made from, in order to specify their performance.
This part of ISO 12856 will be used in conjunction with ISO 12856-2 to be developed in the foreseeable
future.
This part of ISO 12856 applies to sleepers made from plastic materials, including reinforced plastic
materials.
INTERNATIONAL STANDARD ISO 12856-1:2014(E)
Plastics — Plastic railway sleepers for railway applications
(railroad ties) —
Part 1:
Material characteristics
1 Scope
This part of ISO 12856 specifies the characteristics of plastic and reinforced plastic materials to be used
in the manufacturing of railway sleepers.
It is applicable to the sleepers and parts of sleepers to be installed in tracks with or without ballast.
Examples of different types of plastic and reinforced sleepers are given in Annex B.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 62, Plastics — Determination of water absorption
ISO 75 (all parts), Plastics — Determination of temperature of deflection under load
ISO 178, Plastics — Determination of flexural properties
ISO 291, Plastics — Standard atmospheres for conditioning and testing
ISO 306, Plastics — Thermoplastic materials — Determination of Vicat softening temperature (VST)
ISO 527-2, Plastics — Determination of tensile properties — Part 2: Test conditions for moulding and
extrusion plastics
ISO 527-4, Plastics — Determination of tensile properties — Part 4: Test conditions for isotropic and
orthotropic fibre-reinforced plastic composites
ISO 604, Plastics — Determination of compressive properties
ISO 877-1:2009, Plastics — Methods of exposure to solar radiation — Part 1: General guidance
ISO 877-2:2009, Plastics — Methods of exposure to solar radiation — Part 2: Direct weathering and exposure
behind window glass
ISO 1183-1, Plastics — Methods for determining the density of non-cellular plastics — Part 1: Immersion
method, liquid pyknometer method and titration method
ISO 2578, Plastics — Determination of time-temperature limits after prolonged exposure to heat
ISO 3611, Geometrical product specifications (GPS) — Dimensional measuring equipment: Micrometers for
external measurements — Design and metrological characteristics
ISO 4892-2, Plastics — Methods of exposure to laboratory light sources — Part 2: Xenon-arc lamps
ISO 4892-4, Plastics — Methods of exposure to laboratory light sources — Part 4: Open-flame carbon-arc
lamps
ISO 8256, Plastics — Determination of tensile-impact strength
ISO 10640, Plastics — Methodology for assessing polymer photoageing by FTIR and UV/visible spectroscopy
ISO 11357-2, Plastics — Differential scanning calorimetry (DSC) — Part 2: Determination of glass transition
temperature and glass transition step height
ISO 11357-6, Plastics — Differential scanning calorimetry (DSC) — Part 6: Determination of oxidation
induction time (isothermal OIT) and oxidation induction temperature (dynamic OIT)
ISO 11359-2, Plastics — Thermomechanical analysis (TMA) — Part 2: Determination of coefficient of linear
thermal expansion and glass transition temperature
ISO 13385-1, Geometrical product specifications (GPS) — Dimensional measuring equipment — Part 1:
Callipers; Design and metrological characteristics
ISO 13385-2, Geometrical product specifications (GPS) — Dimensional measuring equipment — Part 2:
Calliper depth gauges; Design and metrological characteristics
ISO 14125, Fibre-reinforced plastic composites — Determination of flexural properties
ISO/TR 19032, Plastics — Use of polyethylene reference specimens (PERS) for monitoring laboratory and
outdoor weathering conditions
IEC 60695-11-20:2003, Fire hazard testing — Part 11-20: Test flames — 500 W flame test methods
3 Characteristics
3.1 Material identification
The manufacturer shall declare the following information:
a) type of polymer(s), e.g. thermoplastic or thermosetting, including the main additives and the
materials constituting composite matrix, if any;
b) type, form, structure, and content of reinforcing materials;
c) type, form, and content of filler or increasing-mass materials, if any;
d) description of the manufacturing process.
3.2 Chemical resistance
The material shall not be adversely affected by exposure to chemicals typically found in the railway
environment, such as diesel and grease. Chemical compatibility can be demonstrated either by test
results or it can be documented.
3.3 Physical, mechanical, and electrical characteristics
The physical, mechanical, and electrical characteristics of materials are listed in Tables 1 and 2. The
relevance of assessment on characteristics shall be agreed on between the interested parties. Some of
the tests might not be applicable for anisotropic sleepers or sleepers with specific reinforced material.
Examples of typical plastic sleeper properties are given in Annex B.
2 © ISO 2014 – All rights reserved

Table 1 — Physical, mechanical, and electrical characteristics
Characteristic Unit Test method
Bending strength MPa
4.2
Flexural modulus MPa
Longitudinal compression strength N/mm 4.3
Material strength
Lateral compression strength N/mm 4.4
Shear strength N/mm 4.5
Adhesive shear strength N/mm 4.6
Alternating-current breakdown voltage kV 4.7
Electrical characteristic
Direct-current insulation resistance Ω 4.8
a
Water absorption % 4.9
Mass density g/cm 4.10
−1
Linear expansion coefficient K 4.11
a
Percentage expressed in mass fraction.
Table 2 — Temperature-dependent mechanical properties
Characteristic Unit Test conditions Test method
a
Bending strength %
4.2
a
Flexural modulus %
In air for 24 h
Material strength a
Longitudinal com- %
b
Test temperatures : −30 °C and 60 °C 4.3
pression strength
a
Shear strength % 4.5
a
Percentages indicate the strength retention in comparison with the values determined at an ambient temperature.
b
Test temperatures can vary in the conditions where sleepers are used (tunnels, extreme weather conditions, excessively
exposed locations).
3.4 Weathering resistance
The sleeper shall be designed to guarantee that at the end of its service life, the load-bearing capacities
are sufficient for service even in case of the losses of strength due to weathering.
The requirements for the weathering resistance of the materials shall be agreed on between the
interested parties.
The weathering resistance shall be demonstrated either by a documented and substantially proven
experience or by assessing the properties in accordance with 4.13.1 or 4.13.2, as applicable.
4 Test methods
4.1 General
4.1.1 Preparation of test specimens
There shall be no damage or faults on the surface of the test specimens in order to prevent notch effects.
If there are burrs, they shall be carefully removed without damaging the surface. If necessary, the edges
of the surfaces of the test specimens shall be finished using sandpaper.
4.1.2 Test conditions
Unless otherwise specified in a separate clause, the test shall be carried out in one of the standard
atmospheres specified in ISO 291 after the test specimens are conditioned in the same atmosphere for
at least 24 h.
4.1.3 Tolerance of test specimens
For each test method, the dimensions of the test specimens should be given with tolerances. The nominal
dimension shall be ±1 mm.
4.2 Bending strength and flexural modulus
The test shall be conducted at (23 ± 5) °C using the following method.
The longitudinal direction of the test specimen shall be parallel to the supports and vertical to the load
direction. A steel plate of dimensions 3 mm × 50 mm × 50 mm shall be placed on the test specimen and
positioned in the middle between the supports.
The dimensions of the test specimen shall be:
— length: (240 ± 2) mm,
— width: (50 ± 1) mm,
— thickness: (20 ± 1) mm,
and the span between supports shall be 160 mm to 200 mm.
The concentrated load shall be applied in the middle of the span. The average loading speed (stress) shall
be less than 15 N/mm per minute.
The support shall be robust enough and have sufficient area to touch the test specimen. Both supports
shall be located on the same distances from the centre of the test specimen in the longitudinal direction.
The other details of test arrangements shall refer to ISO 178.
4.3 Longitudinal compressive strength
The longitudinal compressive strength test shall be conducted at (23 ± 5) °C and using the following
method.
The dimensions of the test specimen shall be:
— length: (40 ± 2) mm,
— width: (20 ± 0,5) mm,
— thickness: (20 ± 0,5) mm.
The longitudinal direction of the test specimen is corresponding to the longitudinal direction of the
sleeper. The loading direction shall be parallel to the longitudinal direction of the test specimen.
The loading pressure shall be applied to the test specimen where the specimen is located between two
flat steel plates. The average loading speed (stress) shall be less than 15 N/mm per minute.
The other details of test arrangements shall be referred to ISO 604.
4.4 Lateral compressive strength
The lateral compressive strength test shall be conducted at (23 ± 5) °C using the following method.
4 © ISO 2014 – All rights reserved

The test specimen shall be cut with a length between 500 mm and 700 mm and a width 200 mm and
thickness 100 mm. The loading direction shall be vertical to the longitudinal direction of test specimen.
The loading pressure shall be applied to the test specimen using the flat steel plates both on its top and
bottom sides. The average loading speed (stress) shall be less than 15 N/mm per minute.
The other details of test arrangements shall be referred to ISO 604.
4.5 Shear strength
The shear strength test shall be conducted at (23 ± 5) °C using the following method.
The loading pressure shall be parallel to the longitudinal direction of test specimen. The loading pressure
shall be applied by the method illustrated in Figure 1. The average loading speed (stress) shall be less
than 5,88 N/mm per minute.
The rectangular test specimen with dimensions 40 mm × 50 mm × 52 mm shall be prepared with a cut
portion of 10 mm × 10 mm × 40 mm as shown in Figure 2.
The maximum load refers to the load before the test specimen begins to break (not to deform).
The setting jig shall be robust enough and have sufficient areas to touch the test specimen. In addition,
as illustrated in Figure 1, the setting jig shall have the necessary capacity to hold the test specimen so as
not to be moved even though load is given on the edge of the test specimen.
The tolerance of radius of curvature of the edge of the cut portion and the roughness of contact surface
between the loading block and the test specimen can be defined on the agreement between the interested
parties.
The shear strength shall be determined from the test results using Formula (1).
P
m
τ = (1)
A
where
τ is the shear strength (N/mm );
P is the maximum load (N);
m
A is the cross-sectional area (mm ).
NOTE Refer to ISO 604 for the definition of “maximum load”.
Dimensions in millimetres
F
Key
1 specimen
2 setting jig
3 loading block
F load (or force)
Figure 1 — Loading method for shear strength test
6 © ISO 2014 – All rights reserved

Dimensions in millimetres
Key
A cross-sectional area
Figure 2 — Test specimen for shear strength test
4.6 Adhesive shear strength
For testing, the adhesive material or the method of use shall not be specified.
The adhesive shear strength test shall be conducted at (23 ± 5) °C using the following method.
Alternatively, the test specimen shall be cut out from pre-prepared glued material and then finished
to the shape and dimension as illustrated in Figure 7. The loading direction shall be parallel to the
longitudinal direction of the test specimen and the surface coated with adhesive. The average loading
speed (stress) shall be adjusted to less than 9,8 kN/min. The travel speed of the crosshead shall be
adjusted to be between 0,3 mm/min and 0,5 mm/min, and the loading pressure shall be as given in the
method shown in Figure 6.
The perimeter of the glued surface shall be free from an excess of adhesive. This clause shall apply only
to laminated materials.
The maximum load shall be the load before the test specimen begins to break (not to deform).
The setting jig shall be robust enough and have sufficient areas to touch the test specimen. In addition,
as illustrated in Figure 3, the setting jig shall have the necessary capacity to hold the test specimen so as
not to be moved even though load is given on the edge of test specimen.
F
Key
1 specimen
2 setting jig
3 loading block
F load
Figure 3 — Loading method for shear strength test
8 © ISO 2014 – All rights reserved

Dimensions in millimetres
A
26 26 40
Key
A adhesion surface area
Figure 4 — Test specimen for shear strength test
The adhesive shear strength shall be determined from the test results using Formula (2).
P
m
S = (2)
A
where
S is the shear strength (N/mm );
P is the maximum load (N);
m
A is the adhesive surface area (mm ).
NOTE Refer to ISO 604 for the definition of “maximum load”.
4.7 Alternating-current breakdown voltage
The alternating-current breakdown voltage test shall be conducted using the following method.
The test specimen with the dimensions 20 mm × 80 mm × 100 mm, as shown in Figure 5, shall be
prepared. The longitudinal axis in testing shall be parallel to the longitudinal direction of test specimen.
Prior to the test, the specimen shall be conditioned at (23 ± 1) °C for 48 h. The shape of the electrode
shall be as shown in Figure 6. The electrode equipment shall be set at the central points on the top and
bottom surfaces of the test specimen.
The contact pressure between the electrode equipment shall be about 5 kN. The voltage application
method shall be as in that of a short-time breakdown test. The value of alternating-current breakdown
voltage shall be measured by applying the voltage beginning from 0 V at the speed where insulation
breakdown occurs in between 10 s and 20 s (alternating-current breakdown voltage shall be measured
here).
5 45
It is recommended that the test be conducted at (23 ± 1) °C air temperature with an application of silicon
oil to prevent an air short-circuit.
Applicability of this test can be determined by the interested parties.
Dimensions in millimetres
Figure 5 — Test specimen for alternating-current breakdown voltage test
10 © ISO 2014 – All rights reserved
Dimensions in millimetres
ø20
ø25
Key
1 specimen
2 electrode
Figure 6 — Electrode shape for alternating-current breakdown voltage test
4.8 Direct-current insulation resistance
The direct-current insulation resistance test shall be conducted at (23 ± 5) °C using the following method.
The test specimen with the dimensions 5 mm × 20 mm × 40 mm shall be prepared. The longitudinal axis
in testing shall be parallel to the longitudinal direction of the test specimen.
Prior to the test, the specimen shall be conditioned at (23 ± 1) °C in air for 48 h. Then, two holes shall be
made and finished by a taper pin reamer for insertion of the electrode as illustrated in Figure 7.
The test shall be conducted with the devices composed of electrode, power supply, galvanometer,
universal shunt, switch, etc. in order to measure the direct-current insulation resistance as shown in
Figure 8.
For the electrode, the brass taper pin with 5 mm diameter, which should be free from flaws on the
surface, shall be used. The power supply shall be equipped with a dry cell or a storage battery of 500 V
in the direct voltage.
Applicability of this test can be determined by the interested parties.
Dimensions in millimetres
ø5
Figure 7 — Test specimen for direct-current insulation resistance test
12 © ISO 2014 – All rights reserved
5 6
Key
1 guard
2 electrode
3 test specimen
4 power supply polarity change-over switch
5 universal shunt
6 reference resistance (R )
s
7 galvanometer
8 galvanometer polarity change-over switch
Figure 8 — Direct-current insulation resistance measuring device
The direct-current insulation resistance shall be calculated with the obtained test result using
Formula (3).
S ×θ
RR= (3)
s
S ×θ
where
R is the direct-current insulation resistance (MΩ);
R is the reference resistance (MΩ);
s
S is the magnification of universal shunt at the time of measuring using the reference resistance
R (mm);
s
θ is the deflection of galvanometer at the time of measuring using the reference resistance R
1 s
(mm);
S is the magnification of universal shunt at the time of connecting the test specimen (mm);
θ is the deflection of galvanometer at the time of connecting the test specimen (mm).
4.9 Water absorption
The water absorption test shall be conducted according to ISO 62, method 1.
The test specimen with the dimensions 30 mm × 30 mm × 100 mm shall be prepared and the longitudinal
axis shall be fixed in accordance with the longitudinal direction of the test specimen.
4.10 Mass density
The mass density of raw material shall be measured at (23 ± 5) °C. Based on the result of test, the
mass density shall be determined according to Formula (4). In alternative, the mass density shall be
determined according to ISO 1183-1.
m
ρ= (4)
V
where
ρ is the mass density (g/cm );
m is the mass (g);
V is the measured volume (cm ).
4.11 Linear expansion coefficient
The linear expansion test shall be conducted using the following method.
The test specimen with the dimensions 10 mm × 10 mm × 120 mm shall be prepared and heated from
temperatures of −30 °C to 60 °C in a period of 1 h, and the linear extension of the test specimen shall be
measured to an accuracy of 0,01 mm with the micrometer callipers specified in ISO 3611.
14 © ISO 2014 – All rights reserved

The linear expansion coefficient shall be determined using Formula (5). In alternative, the coefficient of
linear thermal expansion shall be determined according to ISO 11359-2.
l
α = (5)
Lt()−t
where
α is the linear expansion coefficient;
l is the expansion (mm);
L is the length of the test specimen before heating (mm);
t is the ambient temperature at the time of measurement of expansion, i.e. 60 °C (°C);
t is the ambient temperature before heat-up, i.e. −30 °C (°C).
The test method should be established and implemented based upon an agreement between the
interested parties.
4.12 Flame resistance
4.12.1 Option 1
The flame resistance test shall be conducted in accordance with IEC 60695-11-20:2003, 8.3. The results
shall be judged based on the occurrence of flame penetration in the test specimen. To identify non-
combustibility, the flame shall not penetrate any of the five test specimens.
4.12.2 Option 2
The flame resistance test shall be conducted with reference to IEC 60695-11-20:2003, 8.3, except the
condition that the thickness of the test specimen sh
...