Test method for fibre-reinforced cementitious composites — Load-deflection curve using circular plates

This document specifies a test method for evaluating flexural performance of fibre-reinforced cementitious composites (FRCCs) using derived parameters. These parameters are derived from the load-deflection curve obtained by testing a circular specimen supported on a concentric ring and loaded by another ring with a smaller diameter. The performance of FRCCs tested by this method is characterized for biaxial properties. This test method provides for the determination of first-cracking load and the corresponding stress. It also provides for the determination of specimen toughness based on the area under the load-deflection curve up to the deflections at the first-cracking and peak loads. For determining the toughness value, this test method is intended primarily for use with FRCCs that exhibit deflection hardening behaviour. This test method is not intended for materials that exhibit deflection-softening behaviour.

Méthode d'essai des composites à base de ciment renforcés par des fibres — Courbe de charge-déformation utilisant des plaques circulaires

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Status
Published
Publication Date
26-Nov-2018
Current Stage
6060 - International Standard published
Start Date
27-Nov-2018
Completion Date
27-Nov-2018
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ISO 21022:2018 - Test method for fibre-reinforced cementitious composites -- Load-deflection curve using circular plates
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INTERNATIONAL ISO
STANDARD 21022
First edition
2018-11
Test method for fibre-reinforced
cementitious composites — Load-
deflection curve using circular plates
Méthode d'essai des composites à base de ciment renforcés par
des fibres — Courbe de charge-déformation utilisant des plaques
circulaires
Reference number
ISO 21022:2018(E)
ISO 2018
---------------------- Page: 1 ----------------------
ISO 21022:2018(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2018

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

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Published in Switzerland
ii © ISO 2018 – All rights reserved
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ISO 21022:2018(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative reference ......................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Symbols .......................................................................................................................................................................................................................... 2

5 Test specimens........................................................................................................................................................................................................ 3

5.1 Geometry ...................................................................................................................................................................................................... 3

5.2 Fabrication of specimens ............................................................................................................................................................... 4

6 Testing machine and measuring devices..................................................................................................................................... 5

6.1 Testing machine ..................................................................................................................................................................................... 5

6.2 Loading fixtures for concentric ring testing .................................................................................................................. 6

6.2.1 General...................................................................................................................................................................................... 6

6.2.2 Loading and support rings ...................................................................................................................................... 6

6.2.3 Compliant layer and friction elimination.................................................................................................... 6

6.3 Alignment .................................................................................................................................................................................................... 7

6.4 Measuring device for loads ........................................................................................................................................................... 7

6.5 Measuring device for deflection ............................................................................................................................................... 7

6.6 Data acquisition...................................................................................................................................................................................... 8

7 Test procedure ........................................................................................................................................................................................................ 8

7.1 Preparation and positioning of specimens ..................................................................................................................... 8

7.2 Loading .......................................................................................................................................................................................................... 8

7.3 Assessment of fracture patterns .............................................................................................................................................. 8

8 Calculations................................................................................................................................................................................................................ 9

9 Test report ................................................................................................................................................................................................................11

Bibliography .............................................................................................................................................................................................................................13

© ISO 2018 – All rights reserved iii
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ISO 21022:2018(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (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

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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.

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.
iv © ISO 2018 – All rights reserved
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INTERNATIONAL STANDARD ISO 21022:2018(E)
Test method for fibre-reinforced cementitious
composites — Load-deflection curve using circular plates
1 Scope

This document specifies a test method for evaluating flexural performance of fibre-reinforced

cementitious composites (FRCCs) using derived parameters. These parameters are derived from the

load-deflection curve obtained by testing a circular specimen supported on a concentric ring and

loaded by another ring with a smaller diameter. The performance of FRCCs tested by this method is

characterized for biaxial properties.

This test method provides for the determination of first-cracking load and the corresponding stress. It

also provides for the determination of specimen toughness based on the area under the load-deflection

curve up to the deflections at the first-cracking and peak loads. For determining the toughness value,

this test method is intended primarily for use with FRCCs that exhibit deflection hardening behaviour.

This test method is not intended for materials that exhibit deflection-softening behaviour.

2 Normative reference

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 1920-3:2004, Testing of concrete — Part 3: Making and curing test specimens
ISO 1920-4, Testing of concrete — Part 4: Strength of hardened concrete
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
load-deflection curve

plot of load versus net deflection (3.2) obtained from the test of a flexural circular specimen

3.2
net deflection

deflection measured at the centre of a flexural circular specimen exclusive of any extraneous effects due

to seating or twisting of the specimen on its supports or deformation of the support and loading system

3.3
toughness

energy absorbed by the specimen equivalent to the area under the load-deflection curve (3.1) between

the load and a specified net deflection (3.2)
© ISO 2018 – All rights reserved 1
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ISO 21022:2018(E)
3.4
equibiaxial flexural strength

stress that a material is capable of sustaining when it is subjected to an equibiaxial stress state

Note 1 to entry: This equibiaxial stress state is caused by the pure biaxial flexure of the circular specimen loaded by

the inner loading ring and outer support ring. The equibiaxial flexural strength is calculated from the first-cracking

load (3.5) of a biaxial test carried to rupture, the original dimensions of the test specimen and Poisson’s ratio.

3.5
first-cracking load

load value on the load-deflection curve (3.1) at the end of linear elasticity, at which cracking initiates

3.6
first-cracking deflection

net deflection (3.2) value on the load-deflection curve (3.1) at the first-cracking load (3.5)

Note 1 to entry: This is expressed in mm.
3.7
first-cracking strength

stress value obtained when the first-cracking load (3.5) is inserted in the formula for modulus of rupture

Note 1 to entry: This is expressed in MPa.
3.8
peak load
maximum load on the load-deflection curve (3.1)
3.9
peak-load deflection

net deflection (3.2) value on the load-deflection curve (3.1) at the peak load (3.8)

Note 1 to entry: This is expressed in mm.
3.10
Poisson’s ratio

negative value of the ratio of transverse strain to the corresponding axial strain in the elastic range of

deformation
4 Symbols
Symbol Unit Description
t mm thickness of the circular specimen
r mm radius of the loading ring
r mm radius of the specimen
r mm radius of the support ring
f mm r − r
1 2
P N first cracking load
P N peak load
R N/min loading rate
S MPa/min rate of the equibiaxial stress
ψ mm ratio of stress to load
2 © ISO 2018 – All rights reserved
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ISO 21022:2018(E)
5 Test specimens
5.1 Geometry

The nominal maximum size of aggregate and the thickness of the test specimens shall be in accordance

with ISO 1920-3:2004, 4.1. The thickness and diameter of test specimens shall be at least three times

the maximum fibre length.

The preferred size for a circular specimen with FRCCs is 210 mm in radius and 50 mm in thickness

tested on a 400 mm span. A specimen with dimensions different from the preferred specimen sizes is

permissible.

Circular specimens are tested in flexure between two concentric rings, as shown in Figure 1.

Damaged specimens shall not be tested.
a) The ratio of t to r shall be 0,25.
b) The ratio of r to r shall be 0,25.
0 2
c) The difference, f, should be 0,05 times r . A large value of f would
...

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