ISO 10406-4:2025

International
Standard
ISO 10406-4
First edition
Fibre-reinforced polymer (FRP)
2025-09
reinforcement of concrete — Test
methods —
Part 4:
FRP grids
Reference number
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms, definition, and symbols . 2
3.1 Terms and definition .2
3.2 Symbols .4
4 General provision concerning test pieces . 6
5 Test method for physical properties . 6
5.1 Cross-sectional area .6
5.1.1 Test piece .6
5.1.2 Test procedure.7
5.1.3 Calculation .7
5.1.4 Test report .7
5.2 Fibre volume fraction .8
5.2.1 Test pieces .8
5.2.2 Test procedure.8
5.2.3 Calculation .9
5.3 Coefficient of thermal expansion .10
5.3.1 Test pieces .10
5.3.2 Testing device .10
5.3.3 Test method .10
5.3.4 Calculations . .11
5.3.5 Test report .11
6 Test method for short-term mechanical properties .12
6.1 Tensile property . 12
6.1.1 Test pieces . 12
6.1.2 Test equipment . 12
6.1.3 Test procedure. 13
6.1.4 Test temperature . 13
6.1.5 Calculations . . 13
6.1.6 Test report . 15
7 Test method for durability . 17
7.1 Alkali resistance .17
7.1.1 Test pieces .17
7.1.2 Immersion in alkaline solution .17
7.1.3 External appearance and mass change .18
7.1.4 Tensile test .18
7.1.5 Calculations . .18
7.1.6 Test report .19
8 Test method for long-term mechanical properties .20
8.1 Long-term relaxation . 20
8.1.1 Test pieces . 20
8.1.2 Testing frame and devices . 20
8.1.3 Test temperature . .21
8.1.4 Test method .21
8.1.5 Calculations . .21
8.1.6 Test report . 22
8.2 Tensile fatigue strength. 22
8.2.1 Test pieces . 22
8.2.2 Testing machine and devices . 23
8.2.3 Test temperature . 23

iii
8.2.4 Test method . 23
8.2.5 Calculations . .24
8.2.6 Test report .24
8.3 Creep rupture strength . 25
8.3.1 Test pieces . 25
8.3.2 Testing frame and devices . 25
8.3.3 Test temperature . 25
8.3.4 Tensile capacity . 25
8.3.5 Test method . 25
8.3.6 Calculations . . 26
8.3.7 Test report .27
9 Test methods for bond properties .28
9.1 Bond property by pull-out testing . 28
9.1.1 Test pieces . 28
9.1.2 Testing machine and devices . 29
9.1.3 Test method . 29
9.1.4 Calculations . . 30
9.1.5 Test report . 30
9.2 Bond property by single-lap shear test .32
9.2.1 Test pieces .32
9.2.2 Testing machine and devices . 33
9.2.3 Test method . 33
9.2.4 Calculations . . 34
9.2.5 Test report . 35
10 Informative references .36

iv
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 71, Concrete, reinforced concrete and pre-
stressed concrete, Subcommittee SC 6, Non-traditional reinforcing materials for concrete structures.
This first edition cancels and replaces the second edition (ISO 10406-1:2015) which has been technically
revised.
The main changes are as follows:
— inclusion of thermoplastic resin for FRP grids;
— fibre volume fraction testing and single-lap shear bond test methods have been added;
— tensile performance, alkali resistance, and pull-off bond test methods are modified;
— test method for performance of anchorages and couplers, test method for transverse shear strength, and
test method for flexural tensile properties have been deleted.
A list of all parts in the ISO 10406 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

v
Introduction
Fibre Reinforced Polymer (FRP) grids, renowned for their high strength, lightweight nature, excellent
bond behaviour, and superior durability, serve a pivotal role in rehabilitating existing RC structures and
reinforcing new constructions. Incorporating FRP grids effectively within structures, it becomes imperative
to comprehensively understand involves a comprehensive understanding of their physical properties,
mechanical characteristics, long-term performance, durability, and bond capabilities. This understanding
is crucial to ensures that structures reinforced or constructed with FRP grids meet the stringent design
requirements.
However, the prevalent testing methods for FRP bars or sheets, as outlined in existing specifications, are
insufficient in adequately accounting for the spatial bidirectional characteristics inherent in FRP grids.
Therefore, the need arises to develop an internationally recognized standard that specifically delineates
testing methodologies tailored for FRP grids. This document aims to establish a framework for testing
procedures that consider the distinctive spatial bidirectional properties of these grids. Additionally, the
document provides essential material properties data required for structural design, offering engineers
and designers a reliable basis for incorporating FRP grids into their projects. By formulating a document
for testing FRP grids, we endeavor to fill the existing gap in methodologies and facilitate a more accurate
assessment of their performance. This document not only enhances the reliability of structural designs
utilizing FRP grids but also promotes their wider and more efficient use in construction projects worldwide.

vi
International Standard ISO 10406-4:2025(en)
Fibre-reinforced polymer (FRP) reinforcement of concrete —
Test methods —
Part 4:
FRP grids
1 Scope
This document specifies test methods applicable to fibre-reinforced polymer (FRP) grids as reinforcement
or pre-stressing tendons in concrete, including physical, mechanical, durability, long term durability and
bond properties.
FRP grids in this document can be used for rehabilitating existing reinforced concrete (RC) structures and
reinforcing new constructions.
FRP grids in this document are made of fibre and resin matrix. The types of fibres are aramid fibre, basalt
fibre, carbon fibre or glass fibre. The matrix includes thermosetting resins, such as vinylester, unsaturated
polyester resins, as well as thermoplastic resins, including polypropylene, polyamides, and polymethyl
methacrylate.
FRP grids in this document are a rigid array of interconnected FRP bars, and do not include fibre textile and
fabric with a mesh type.
In this document, durability refers to alkali resistance.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements 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.
ISO 3611,
Geometrical product specifications (GPS) — Dimensional measuring equipment — Design and metrological
characteristics of micrometers for external measurements
ISO 4788, Laboratory glassware — Graduated measuring cylinders
ISO 291:2008, Plastics — Standard atmospheres for conditioning and testing
ISO 7500-1, Metallic materials — Calibration and verification of static uniaxial testing machines — Part 1:
Tension/compression testing machines — Calibration and verification of the force-measuring system
ISO 13385-1, Geometrical product specifications (GPS) — Dimensional measuring equipment — Part 1: Design
and metrological characteristics of callipers
ISO 1172:2023, Textile-glass-reinforced plastics — Prepregs, moulding compounds and laminates —
Determination of the textile-glass and mineral-filler content using calcination methods
ISO 80000-1:2022, Quantities and units — Part 1: General

3 Terms, definition, and symbols
3.1 Terms and definition
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1.1
alkali
condition of having or containing hydroxyl (OH-) ions; containing alkaline substances
Note 1 to entry: In concrete, the initial alkaline environment has a pH above 13.
3.1.2
anchoring section
end part of a test piece where an anchorage is fitted to transmit loads from the testing machine to the test section
3.1.3
average load
average of the maximum and minimum repeated load
3.1.4
coefficient of thermal expansion
average coefficient of linear thermal expansion between given temperatures
Note 1 to entry: The average of the given temperatures is taken as the representative temperature.
3.1.5
creep failure capacity
load causing failure after a specified period of time from the start of a sustained load
Note 1 to entry: In particular, the load causing failure after 1 million hours is referred to as the million-hour creep
failure capacity.
3.1.6
creep failure strength
stress causing failure after a specified period of time from the start of a sustained load
Note 1 to entry: In particular, the load causing failure after 1 million hours is referred to as the million-hour creep
failure strength.
3.1.7
creep failure time
time between the start of a sustained load and failure of a test piece
3.1.8
creep failure
failure occurring in a test piece due to a sustained load
3.1.9
creep strain
differential change in length per unit length occurring in a test piece due to creep
3.1.10
creep
time-dependent deformation of a FRP grid subjected to a sustained load at a constant temperature

3.1.11
fatigue strength
maximum repeated stress at which the test piece does not fail at the prescribed number of cycles
3.1.12
fibre-reinforced polymer
FRP
composite material, moulded and hardened to the intended shape, consisting of continuous fibre impregnated
with a fibre-binding polymer
3.1.13
fibre-reinforced polymer grid
FRP grid
two-dimensional (planar) or three-dimensional (spatial) rigid array of interconnected FRP bars that form a
continuous lattice that can be used to reinforce concrete
3.1.14
fibre-reinforced polymer grid segment
FRP grid segment
a strip of single or multiple strands of fibres that are impregnated and solidified with resin and arranged in
parallel along the warp or weft direction
3.1.15
fibre area of grid segment
fibre area on the cross section of grid segment
3.1.16
fibre volume fraction
the ratio of the volume of fibres to the volume of the composite
3.1.17
frequency
number of loading cycles in one second during the test
3.1.18
gauge length
straight portion along the length of a test piece used to measure the elongation using an extensometer, or a
similar device
3.1.19
load amplitude
one-half of the load range
3.1.20
load range
difference between maximum and minimum repeated load
3.1.21
maximum repeated load
maximum load during repeated loading
3.1.22
minimum repeated load
minimum load during repeated loading
3.1.23
nominal cross-sectional area
value obtained upon dividing the volume of the FRP specimen by its length

3.1.24
nominal perimeter
peripheral length of the FRP grid segment
Note 1 to entry: The peripheral length of the FRP grid segment forms the basis for calculation of bond strength and
shall be determined separately for each grid segment.
3.1.25
number of cycles
number of times the repeated load is applied to the test piece
3.1.26
relaxation
time-dependent decrease in load in a FRP held at a given constant temperature with a prescribed initial load
applied and held at a given constant strain
3.1.27
relaxation rate
percentage reduction in load relative to the initial load after a given period of time, under a fixed strain
Note 1 to entry: In particular, the relaxation value after 1 million hours (approximately 114 years) is referred to as the
hundred-year relaxation rate.
3.1.28
repeated load
load alternating cyclically between fixed maximum and minimum values
3.1.29
S-N curve
plotted on a graph with repeated stress on the vertical axis and the number of cycles to fatigue failure on the
horizontal axis
3.1.30
thermo mechanical analysis
TMA
method for measuring deformation of a material as a function of either temperature or time, by varying the
temperature of the material according to a calibrated program, under a non-vibrating load
3.1.31
thermo mechanical analysis curve
TMA curve
graph, in the context of TMA, with temperature or time represented on the horizontal axis, and deformation
on the vertical axis
3.1.32
ultimate strain
strain corresponding to the tensile strength
3.2 Symbols
See Table 1.
Table 1 — Symbols
Symbol Unit Description Reference
A mm Nominal cross-sectional area of test piece 5.1, 6.1, 8.3
A mm Fibre area of grid segment 6.1, 8.3
f
b mm Average bond width of embedded FRP grid 9.2
av
E N/mm Young’s modulus calculated based on cross-sectional area 6.1, 9.2
E N/mm Young’s modulus calculated based on fibre area 6.1, 9.2
f
f N/mm Tensile strength calculated based fibre area 6.1
fu
f N/mm Tensile strength calculated based cross-sectional area 6.1
u
F N Million-hour creep rupture capacity 8.3
r
F N Maximum tensile force 6.1
u
F N Tensile capacity befor immersion 7.1
u0
F N Tensile capacity after immersion 7.1
u1
G N/mm Interfacial fracture energy calculated based on the cross section of FRP grid 9.2
f
G N/mm Interfacial fracture energy calculated based on the fibre section of FRP grid 9.2
ff
k Empirical constant 8.1, 8.3
a
k Empirical constant 8.1, 8.3
b
K N Tensile rigidity calculated based on cross-sectional area 6.1
K N Tensile rigidity calculated based on fibre area 6.1
f
l mm Bonded length for pullout test 9.1
l mm Length of test piece 5.1
l mm Effective bond length of embedded FRP grid 9.2
e
L mm Length of test piece at room temperature 5.3
L mm Length before immersion 7.1
L mm Length after immersion 7.1
m g Initial mass, in grams, of the dry boat or crucible 5.2
m g Mass before immersion 7.1
m g Mass after immersion 7.1
m g The initial mass, in grams, of the boat or crucible plus dried specimen 5.2
m g The final mass, in grams, of the boat or crucible plus residue after calcination 5.2
M g Fibre content of FRP grid 5.2
f
P N Tensile load in the pullout test 9.1
P N Maximum load in the single-lap shear test 9.2
max
P N Specified time creep rupture capacity 8.3
r
R % Tensile capacity retention rate 7.1
et
R Creep load ratio 8.3
Yc
R % Rate of mass change 7.1
Δm
t hour Time 8.1, 8.3
t mm Equivalent width of n FRP grid segments based on cross-section 9.2
e
t mm Equivalent width of n FRP grid segments based on fibre section 9.2
fe
Minimum temperature for calculation of coefficient of thermal expansion 5.3
T °C
(normally 0 °C)
Maximum temperature for calculation of coefficient of thermal expansion 5.3
T °C
(normally 60 °C)
u mm Nominal perimeter of every embedded FRP grid segment 9.1
V mm Volume of water in the measuring cylinder 5.1
V % Fibre volume fraction 5.2
f
TTabablele 1 1 ((ccoonnttiinnueuedd))
Symbol Unit Description Reference
V mm Volume of the sum total of water and test piece 5.1
s
Y % Relaxation rate 8.1, 8.3
α 1/°C Coefficient of thermal expansion 5.3
sp
Coefficient of thermal expansion calculated for specifications test piece for 5.3
α 1/°C
set
length calibration between temperatures T and T
1 2
ΔF N Difference between loads at 20 % and 50 % of maximum tensile force 6.1
Difference in length of specifications test piece for length calibration be- 5.3
ΔL mm
refm
tween temperatures T and T
1 2
ΔL 5.3
mm Difference in length of test piece between temperatures T and T
spm
1 2
Δε Strain difference between ΔF 6.1
ε Ultimate strain calculated based fibre area 6.1
fu
ε Ultimate strain calculated based on cross-sectional area 6.1
u
ρ g/cm Density of fibre 5.2
f
ρ g/cm Density of FRP grid 5.2
g
τ N/mm Bond strength for pullout test 9.1
τ N/mm Bond strength for single-lap shear test 9.2
u
4 General provision concerning test pieces
Unless otherwise agreed, test pieces shall be taken from the grid in the ‘as-delivered’ condition.
In cases when test pieces are taken from a coil, the test piece shall be straightened prior to any test by simple
bending operation with a minimum amount of plastic deformation.
For the determination of the mechanical properties in the tensile and bond tests, the test piece may be
artificially aged (after straightening, if applicable) depending on the performance requirements of the
product.
When a test piece is aged, the conditions of the ageing treatment shall be stated in the test report.
5 Test method for physical properties
5.1 Cross-sectional area
5.1.1 Test piece
5.1.1.1 Preparation of test piece
Test piece shall be cut to predetermined size and finished flat at its cut end from the parent material (FRP)
for tensile test.
5.1.1.2 Length of test piece
The length of the test piece shall be 100 mm when nominal approximate width is 10 mm or less, and 200 mm
when approximate width of FRP grid segment is over 10 mm.
5.1.1.3 Number of test piece
The number of test pieces shall be at least five, taken from the warp-direction and weft-direction parent
material of the same lot.
5.1.2 Test procedure
The test procedure is as follows:
a) The length of test piece shall be measured using the vernier callipers as specified in ISO 13385-1. A
measurement part is made into three places; the three average values shall be rounded off to one figure
below a decimal point; it is the length of test piece.
b) The volume of test piece shall be measured using the measuring cylinder as specified in ISO-4788
according to the approximate diameter of the test piece. Table 2 shows the relationship between
approximate diameter of test piece and capacity of measuring cylinder. When there are two or more
capacities, the minimum capacity cylinder in the range that may be measured shall be chosen.
c) The waterworks water of a proper quantity is put into the measuring cylinder, and the volume is
measured. When the air bubbles, which can cause an error of measurement, are generated on the surface
of the test piece, the surface-tension-reducing solvent such as ethanol etc. shall be added in water to
control generating of air bubbles. When the test piece is in the measuring cylinder, the water shall cover
the test piece, and the top of the water shall be in the range of scale.
d) The test piece is inserted into the measuring cylinder, and the volume of the sum total of water and the
test piece is measured.
e) The test temperature shall be within the range 15 °C to 25 °C (or 20 °C to 30 °C when the climate is hot).
Table 2 — Relationship between approximate diameter of test piece and capacity of measuring
cylinder
Capacity of measuring cylinder
Approximate width of test piece (mm)
(ml)
under 10 10 or 20
11 to 13 25
14 to 20 50 or 100
21 to 25 100
over 25 300 or 500
5.1.3 Calculation
Nominal cross-sectional area shall be calculated using Formula (1), rounded off to one figure below a
decimal point. The nominal cross-section area includes the area of surface-bonded sand particles, and other
non-load-bearing area.
VV−
s0
A= (1)
l
where
A nominal cross-sectional area (mm );
V volume of the sum total of water and test piece (mm );
s
V volume of water in the measuring cylinder (mm );
l length of test piece (mm).
5.1.4 Test report
The test report shall include the following mandatory information:
a) the sample (including name, shape, date of manufacture and lot number of FRP grids tested);
b) the International Standard used (including its year of publication);

c) the method used (if the standard includes several);
d) any deviations from the procedure;
e) any unusual features observed;
f) the date of the test;
g) test temperature;
h) nominal cross-sectional area of wrap-direction and weft-direction girds;
i) capacity of measuring cylinder used in the test;
j) length of test piece;
k) volume of water in the measuring cylinder;
l) volume of the sum total of water and the test piece;
m) name of the solvent, if any solvent is used in the test.
5.2 Fibre volume fraction
5.2.1 Test pieces
5.2.1.1 Preparation of test piece
The test pieces shall be fully representative of the FRP grid examined. They shall be obtained in accordance
with ISO 1172.
5.2.1.2 Mass of test piece
The mass of each piece shall be within the range of 2 g to10 g, and the maximum dimension shall be not more
than 25 mm × 25 mm × 5 mm.
5.2.1.3 Number of test piece
The number of test piece shall be five from the warp-direction and weft-direction parent material of the
same lot at least.
5.2.2 Test procedure
The test procedure is as follows:
a) Weigh the clean, dry boat or crucible to the nearest 0,1 mg on the balance. Place in the muffle furnace set
to the chosen temperature, and leave for 10 min. After cooling to ambient temperature in the desiccator
verify that the mass has not changed. If there has been a change, repeat these operations until constant
mass is reached. Record the mass in grams m ;
b) Place a specimen in the boat or crucible and dry in the ventilated drying oven at 105 °C to constant mass;
c) Cool to ambient temperature in the desiccator and reweight. Record the mass in grams in grams as m ;
d) Place the boat or crucible containing the test specimen in the muffle furnace, preheated to a temperature
of 625 °C and heat to constant mass;
e) For FRP grids with glass, which will not withstand this calcination temperature, a temperature between
500 °C to 600 °C may be used, in accordance with the specification for the glass. It is essential maintain
the chosen temperature constant ±20 °C;

f) Allow the boat or crucible, together with the residue, to cool in the desiccator to ambient temperature
and reweight. Record the mass in the grams as m .
5.2.3 Calculation
5.2.3.1 General
If the results of the individual measurements differ by more than 5 % in relative value, carry out an
additional determination on a third specimen taken from the same location in the elementary unit or
laboratory sample.
5.2.3.2 Fibre content
Calculate, for each specimen, the fibre content M , expressed as a percentage of the initial mass, using
f
Formula (2):
mm−
M = ×100 (2)
f
mm−
where
M fibre content of the FRP grid segment (%);
f
m initial mass of the dry boat or crucible (g);
m initial mass of the boat or crucible plus dried specimen (g);
m final mass of the boat or crucible plus residue after calcination (g).
5.2.3.3 Fibre volume fraction
The fibre volume fraction shall be calculated according to Formula (3):
ρ
f
VM=⋅ (3)
ff
ρ
g
where
M the fibre content (%);
f
ρ the density of fibre, provided by the manufacturer (g/cm );
f
ρ the density of FRP grid, provided by the manufacturer (g/cm ).
g
5.2.3.4 Test report
The test report shall include the following items:
a) the sample (including name, shape, date of manufacture and lot number of FRP tested);
b) the International Standard used (including its year of publication);
c) the method used (if the standard includes several);
d) type of fibre and fibre binding material;
e) numbers or identification marks of test pieces;
f) the dimensions and/or mass of the specimens;
g) the calcination temperature, if different from (625 ± 20) °C;
h) any deviations from the procedure;
i) any unusual features observed;

j) date of test.
5.3 Coefficient of thermal expansion
5.3.1 Test pieces
5.3.1.1 Pre-test curing of test pieces
Prior to testing, test pieces shall be kept for a minimum of 24 hours at a temperature of (23 ± 2) °C and
relative humidity of (50 ± 10) %, under Specifications Temperature Conditions Class II and Specifications
Humidity Conditions Class II, in accordance with ISO 291. The test pieces shall then normally be kept for
48 hours at the maximum test temperature, in order to eliminate strain resulting from bending, and for
dehumidification and deaeration.
5.3.1.2 Dimensions of test piece
The specifications test piece cut from the FRP grid shall be 20 mm in length, with a square cross-section of
breadth of not more than 5 mm.
5.3.1.3 Number of test pieces
The number of test piece shall be five from the warp-direction and weft-direction parent material of the
same lot at least.
5.3.2 Testing device
5.3.2.1 Testing device
The TMA apparatus used for testing shall be capable of measuring in compression mode, of maintaining a
constant atmosphere around the test piece, and of raising the temperature of the test piece at a constant rate.
5.3.2.2 Calibration of testing device
The displacement gauge and temperature gauge shall be periodically calibrated according to the following
principles:
a) Sensitivity calibration of the displacement gauge shall be use either an external micrometre as defined
in ISO 3611, or a micrometre attached to the testing machine.
b) Calibration of the temperature gauge shall be carried out using a pure substance of known melting point.
5.3.2.3 Installation of testing device
The TMA apparatus shall be installed in a location not subject to vibration during testing.
5.3.3 Test method
The test procedure is as follows:
a) The test piece, gauge rod and test platform shall be cleaned, and the test piece placed upright and if
possible bonded to the platform.
b) The gauge rod shall be placed in the centre of the test piece, with no pressure applied.
c) The atmosphere around the test piece shall consist of dry air (water content not more than 0,1 % w/w)
or nitrogen (water content not more than 0,001 % w/w, oxygen content not more than 0,001 % w/w),
maintained at a flow rate in the range of (50 to 100) ml/min.

d) The load shall be applied gently to the tip of the gauge rod at room temperature, and the temperature
shall first be lowered to 0 °C then raised to 60 °C, and the full process of displacement of the test piece
shall be recorded.
e) The rate of temperature increase shall not be more than 5 °C per minute.
f) The compressive stress acting on the test piece shall be around 3 N/ mm .
5.3.4 Calculations
5.3.4.1 Coefficient of thermal expansion
The coefficient of thermal expansion of the test piece within the measured temperature range (T toT ) shall
1 2
be calculated according to Formula (4).
αα=−ΔΔLL LT×−T + (4)
{}()
()
sp spmrefms21 et
where
α coefficient of thermal expansion (/°C);
sp
ΔL difference in length of test piece between temperatures T and T (mm);
spm 1 2
ΔL difference in length of specifications test piece for length calibration between temperatures T
refm 1
and T (mm);
L length of test piece at room temperature (mm);
T maximum temperature for calculation of coefficient of thermal expansion (normally 60 °C);
T minimum temperature for calculation of coefficient of thermal expansion (normally 0 °C);
α coefficient of thermal expansion calculated for specifications test piece for length calibration
set
between temperatures T and T (/°C).
1 2
For apparatus in which the test piece and specifications test piece for length calibration are measured
simultaneously, ΔL shall be = 0 in Formula (4).
refm
5.3.4.2 Rounding off of numerical values
-7
Each of the coefficients of thermal expansion shall be calculated to six decimal places (10 ), and the average
-6
value shall be rounded off to five decimal places (10 ). If the average value is less
...