ISO 5091-1:2023
(Main)Structural intervention of existing concrete structures using cementitious materials — Part 1: General principles
Structural intervention of existing concrete structures using cementitious materials — Part 1: General principles
This document specifies the standards for design, construction and maintenance following completion of intervention to be applied for performing intervention work using cementitious materials to improve the performance of existing concrete structures. The intervention dealt with in this document is intended to restore, sustain or improve the mechanical performance of concrete structures. When the intervention is aimed at restoring or improving durability, reference should be made to relevant documents. This document covers the overlaying, underlaying and jacketing methods using cementitious materials. The intervention with cementitious materials is covered in ISO 16311-1, Clause 4.
Intervention structurelle sur les structures en béton existantes utilisant des matériaux cimentaires — Partie 1: Principes généraux
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INTERNATIONAL ISO
STANDARD 5091-1
First edition
2023-07
Structural intervention of
existing concrete structures using
cementitious materials —
Part 1:
General principles
Intervention structurelle sur les structures en béton existantes
utilisant des matériaux cimentaires —
Partie 1: Principes généraux
Reference number
ISO 5091-1:2023(E)
© ISO 2023
---------------------- Page: 1 ----------------------
ISO 5091-1:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2023
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
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ISO 5091-1:2023(E)
Contents Page
Foreword .v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Investigation of existing structure.3
4.1 General . 3
4.2 Investigation . 3
4.2.1 Investigation using documents, records . 3
4.2.2 On-site investigation . 4
5 Intervention design. 4
5.1 General . 4
5.2 Structural plan . 4
5.3 Structural details . 4
6 Materials . 5
6.1 General . 5
6.2 Materials in existing structure . 5
6.3 Materials used in repairing or strengthening parts . 6
6.3.1 General . 6
6.3.2 Cementitious materials . 6
6.3.3 Reinforcing materials . 7
6.3.4 Filling materials . 7
6.3.5 Bonding products . 8
6.4 Characteristic values and design values of materials . 8
6.4.1 General . 8
6.4.2 Cementitious materials . 8
6.4.3 Reinforcing materials . 10
6.4.4 Bonding products . 10
7 Actions .11
7.1 General . 11
7.2 Actions for intervention design . 11
8 Performance verification for repaired or strengthened structure .12
8.1 General .12
8.2 Calculation of response values . 13
8.2.1 General .13
8.2.2 Modelling . 13
8.2.3 Structural analysis . 13
8.2.4 Calculation of response values . 13
8.3 Durability verification . 14
8.3.1 General . 14
8.3.2 Verification related to steel corrosion . 14
8.3.3 Verification related to degradation of cementitious materials.15
8.4 Safety verification . 15
8.4.1 General .15
8.4.2 Verification related to failure . 15
8.4.3 Verification related to fatigue failure . 16
8.5 Serviceability verification . 17
8.5.1 General . 17
8.5.2 Stress level limit . 17
8.5.3 Verification related to appearance . 17
8.5.4 Verification related to vibration . 17
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ISO 5091-1:2023(E)
8.5.5 Verification related to water-tightness . 17
8.6 Restorability verification . 17
8.6.1 General . 17
8.6.2 Structural details related to seismic performance . 18
8.7 Structural details . 18
9 Execution .18
9.1 General . 18
9.2 Construction plan . 18
9.3 Construction . 18
9.4 Inspection . 18
10 Records . .18
11 Maintenance .19
Annex A (informative) Examples of test and design method .20
Bibliography .22
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ISO 5091-1:2023(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 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 7, Maintenance and repair of concrete structures.
A list of all parts in the ISO 5091 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.
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ISO 5091-1:2023(E)
Introduction
As a repairing and strengthening method, attaching of a cementitious material layer to surface of
existing concrete structures has been widely accepted. Since the cementitious layer does not have
enough tensile strength, tension reinforcement is generally placed in the cementitious layer. There are
two types of attaching. For the first way, the cementitious layer is attached either on the top surface
or bottom surface of horizontal concrete members, especially slabs, while, for the second way, the
cementitious layer is attached to jacket vertical concrete members, especially columns. There has
not been any ISO standard on design, execution and maintenance for this method with attaching a
cementitious layer. The ISO 5091 series serves as the first ISO standard for the intervention by attaching
a cementitious material layer with tension reinforcement inside.
At the same time, the ISO 5091 series is the first ISO standard developed for a specific intervention
method, which conforms to the umbrella code, ISO 16311, especially ISO 16311-3 and ISO 16311-4.
The ISO 5091 series consists of four parts. ISO 5091-1 provides the issues common to all three parts,
while ISO 5091-2, 3 and 4 provide the issues specific to each attaching way of cementitious material
layers.
The ISO 5091 series can serve as a practical standard for construction industry, such as client, design
consultant and general contractor, to apply the structural intervention with externally attached
cementitious layer. Additional technical information, which is not provided explicitly in the ISO 5091
series, needs to be provided in each application case with consideration of the provisions of the ISO 5091
series.
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INTERNATIONAL STANDARD ISO 5091-1:2023(E)
Structural intervention of existing concrete structures
using cementitious materials —
Part 1:
General principles
1 Scope
This document specifies the standards for design, construction and maintenance following completion
of intervention to be applied for performing intervention work using cementitious materials to improve
the performance of existing concrete structures. The intervention dealt with in this document is
intended to restore, sustain or improve the mechanical performance of concrete structures. When
the intervention is aimed at restoring or improving durability, reference should be made to relevant
documents.
This document covers the overlaying, underlaying and jacketing methods using cementitious materials.
The intervention with cementitious materials is covered in ISO 16311-1, Clause 4.
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 16311-1:2014, Maintenance and repair of concrete structures — Part 1: General principles
ISO 16311-2, Maintenance and repair of concrete structures — Part 2: Assessment of existing concrete
structures
ISO 16311-3, Maintenance and repair of concrete structures — Part 3: Design of repairs and prevention
ISO 16311-4:2014, Maintenance and repair of concrete structures — Part 4: Execution of repairs and
prevention
ISO 19338, Performance and assessment requirements for design standards on structural concrete
ISO 10406-1, Fibre-reinforced polymer (FRP) reinforcement of concrete — Test methods — Part 1: FRP
bars and grids
ISO 10406-2, Fibre-reinforced polymer (FRP) reinforcement of concrete — Test methods — Part 2: FRP
sheets
ISO 10406-3, Fibre-reinforced polymer (FRP) reinforcement of concrete — Test methods — Part 3: CFRP
strips
ISO 22966, Execution of concrete structures
ISO 679, Cement — Test methods — Determination of strength
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
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ISO 5091-1:2023(E)
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
top-surface overlaying
method in which the thickness of the structural element associated with the top surface of the existing
concrete members is increased using cementitious materials, which will generally be reinforced
Note 1 to entry: The technique enhances the performance (e.g. strength, stiffness) of the existing concrete
structure and is applicable to highway bridge decks, etc.
3.2
bottom-surface (soffit) underlaying
method in which the thickness of the structural element associated with the bottom surface of the
existing concrete is increased using cementitious materials, which will generally be reinforced
Note 1 to entry: The technique enhances the performance (e.g. strength, stiffness) of the existing concrete
structure and is applicable to highway bridge decks, tunnel linings, box culverts/waterway structures, beams,
etc.
3.3
jacketing
method in which additional cementitious materials and associated reinforcement are added to the
periphery of the existing concrete member to increase its strength, stiffness and/or ductility
Note 1 to entry: It is applicable to columns, bridge piers, rigid-frame pier beams, etc.
3.4
bonding product
material, such as a primer or adhesive, that is applied to bond concrete and mortar
Note 1 to entry: The grouting material for bonding concrete and reinforcing material is also included in this term.
3.5
filling material
material injected to fill the gap between a reinforcing material, such as intermediate penetrating tie,
and concrete
3.6
intermediate penetrating tie
reinforcing member, generally made of steel or fibre-reinforced polymer (FRP), that is installed inside
the drilled hole and glued into the concrete substrate to improve the ductility and shear strength of
bridge piers
3.7
very high early strength cement
type of cement with a typical mix proportion that develops a compressive strength as high as 20 N/
2 2
mm to 30 N/mm within 2 h to 3 h of placement
3.8
reinforcing material
steel or FRP material used to sustain, restore or improve the mechanical performance of a structure
3.9
polymer hydraulic cement mortar
hydraulic composition made cementitious materials and fine aggregate modified by the addition of a
polymer
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ISO 5091-1:2023(E)
3.10
overlaying material
cementitious material, potentially reinforced, added on the top surface of an existing concrete structure
for the purpose of making an intervention to enhance the performance of that structure
3.11
underlaying material
cementitious material, potentially reinforced, added on the bottom surface (soffit) of an existing
concrete structure for the purpose of making an intervention to enhance the performance of that
structure
3.12
design response value
value of structural response obtained by numerical analysis on design process, such as sectional force
and deformation
3.13
design limit value
design value for quantified limit state on design process, such as strength of element, allowable crack
width
3.14
cross section failure
loss or decrease of load carrying capacity of structural member due to the excessive action more than
which is more than cross sectional strength, such as flexure, shear and axial strength
3.15
maintainability
ability of a structure to meet service objectives with a minimum expenditure of maintenance effort
under service conditions in which maintenance and repair are performed
4 Investigation of existing structure
4.1 General
The existing structure for which intervention is to be considered shall be investigated in detail to
obtain the information necessary for intervention design and construction. The necessary information
for intervention is additional to and/or different from the information obtained from assessment of
existing structure as maintenance activities, which shall be obtained from ISO 13822 and ISO 16311-1
and ISO 16311-2.
4.2 Investigation
4.2.1 Investigation using documents, records
When an investigation is conducted using documents, records, etc., the climatic conditions,
environmental conditions, geographical conditions and other relevant conditions of the local site shall
be understood in detail from the following viewpoints:
— formulation of material and structural plans;
— formulation of a construction plan;
— maintenance following completion of intervention.
Generally, the workability and hardening characteristics of cementitious materials greatly change
depending on the construction environment, such as temperature. It is therefore necessary to take into
account the climate of the local site during the period when construction is planned to be performed.
Also, for intervention using cementitious materials, the restrictions of the local site regarding the
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ISO 5091-1:2023(E)
construction space as well as the carry-in and installation of materials and equipment needs to be
understood before a specific construction plan is formulated.
4.2.2 On-site investigation
On the site, an investigation shall be conducted to check degradation, damage and initial defects of the
existing concrete structure from the following viewpoints:
— securing of integrity between the existing parts and strengthening parts;
— prediction of durability and degradation after intervention.
In obtaining the expected effect of intervention using cementitious materials, integrity between the
repairing or strengthening parts and existing structure is important. For ensuring integrity, it is
necessary to take measures based on the understanding of degradation, such as carbonation of the
surface of the existing structure, damage such as cracks, splash or leakage of water, etc.
Degradation of a concrete structure after intervention progresses at a different rate depending on the
type of cause and degree of degradation. Therefore, before intervention is performed for a damaged
concrete structure, it is necessary to understand the cause and degree of degradation.
5 Intervention design
5.1 General
In intervention design, a rational structural plan shall be formulated, and structural details shall be
established based on that plan so that intervention restores the performance of the existing structure
to the required level and that the structure after intervention fulfils the required performance
throughout the remaining design service life. The required performance shall be determined according
to ISO 19338.
5.2 Structural plan
In the structural plan, the intervention method shall be selected, taking into consideration the
structural properties, materials, construction method, maintenance method, economy, etc., so as to
ensure that the structure after intervention fulfils the required performance throughout the design
service life.
When considering structural details, not only the design documents created at the time of new
construction but also the current condition of the existing structure identified through field
measurements and other activities shall be taken into consideration.
If a change has already occurred in the intervention target structure, it is necessary to consider an
appropriate measure to prevent the progress of the change from affecting the effect of intervention.
Ensuring compatibility between the existing parts and strengthening parts is particularly important
for preventing the structure after intervention from experiencing early performance degradation.
The intervention methods and materials are selected to ensure that maintenance work such as
inspections and performance evaluations can be efficiently conducted on the structure after
intervention. The costs required for corrective measures shall be minimized through the selection.
Changes that can occur in the structure after the intervention need be detected.
5.3 Structural details
The bonding method of reinforcing materials shall be selected appropriately to ensure that the
structure after intervention achieves the required level of performance.
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ISO 5091-1:2023(E)
In the verification of the serviceability and safety of the structure after intervention, it is assumed that
the existing parts and strengthening parts are integrated to resist external forces. A bonding method
that ensures sufficient integrity for the structure after intervention should be considered.
The reinforcing materials to be used and the structural properties of the strengthening parts shall
be selected so that the structure after intervention sustains the required load-carrying capacity and
stiffness.
Specifically, it should be carefully examined whether the weight of the strengthening part is transferred
to the existing structure or is borne by the strengthening part itself. It is important to set the stiffness
ratio of the existing parts and str
...
DRAFT INTERNATIONAL STANDARD
ISO/DIS 5091-1
ISO/TC 71/SC 7 Secretariat: KATS
Voting begins on: Voting terminates on:
2022-07-18 2022-10-10
Structural intervention of existing concrete structures
using cementitious materials —
Part 1:
General principles
ICS: 91.080.40
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
This document is circulated as received from the committee secretariat.
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 5091-1:2022(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION. © ISO 2022
---------------------- Page: 1 ----------------------
ISO/DIS 5091-1:2022(E)
DRAFT INTERNATIONAL STANDARD
ISO/DIS 5091-1
ISO/TC 71/SC 7 Secretariat: KATS
Voting begins on: Voting terminates on:
Structural intervention of existing concrete structures
using cementitious materials —
Part 1:
General principles
ICS: 91.080.40
COPYRIGHT PROTECTED DOCUMENT
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
© ISO 2022
THEREFORE SUBJECT TO CHANGE AND MAY
This document is circulated as received from the committee secretariat.
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
NOT BE REFERRED TO AS AN INTERNATIONAL
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on STANDARD UNTIL PUBLISHED AS SUCH.
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
IN ADDITION TO THEIR EVALUATION AS
or ISO’s member body in the country of the requester. BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
ISO copyright office
USER PURPOSES, DRAFT INTERNATIONAL
CP 401 • Ch. de Blandonnet 8
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
CH-1214 Vernier, Geneva
POTENTIAL TO BECOME STANDARDS TO
Phone: +41 22 749 01 11
WHICH REFERENCE MAY BE MADE IN
Reference number
Email: copyright@iso.org
NATIONAL REGULATIONS.
Website: www.iso.org ISO/DIS 5091-1:2022(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
Published in Switzerland
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
ii
© ISO 2022 – All rights reserved
PROVIDE SUPPORTING DOCUMENTATION. © ISO 2022
---------------------- Page: 2 ----------------------
ISO/DIS 5091-1:2022(E)
Contents Page
Foreword .v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Investigation of existing structure.4
4.1 General . 4
4.2 Investigation . 4
4.2.1 Investigation using documents, records, etc. . 4
4.2.2 On-site investigation . 4
5 Intervention design. 5
5.1 General . 5
5.2 Structural plan . 5
5.3 Structural details . 6
6 Materials . 7
6.1 General . 7
6.2 Materials in existing structure . 7
6.3 Materials used in repairing or strengthening parts . 8
6.3.1 General . 8
6.3.2 Cementitious materials . 8
6.3.3 Reinforcing materials . 9
6.3.4 Filling materials . 10
6.3.5 Bonding products . 10
6.4 Characteristic values and design values of materials . 11
6.4.1 General . 11
6.4.2 Cementitious materials . 11
6.4.3 Reinforcing materials .13
6.4.4 Bonding products . 14
7 Actions .14
7.1 General . 14
7.2 Actions for intervention design .15
8 Performance verification for repaired or strengthened structure .15
8.1 General . 15
8.2 Calculation of response values . 16
8.2.1 General . 16
8.2.2 Modeling . 17
8.2.3 Structural analysis . 17
8.2.4 Calculation of response values . 18
8.3 Durability verification . 18
8.3.1 General . 18
8.3.2 Verification related to steel corrosion . 19
8.3.3 Verification related to degradation of cementitious materials.20
8.4 Safety verification . 20
8.4.1 General .20
8.4.2 Verification related to failure . 21
8.4.3 Verification related to fatigue failure . 22
8.5 Serviceability verification . 23
8.5.1 General .23
8.5.2 Stress level limit . 23
8.5.3 Verification related to appearance . 23
8.5.4 Verification related to vibration . 24
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ISO/DIS 5091-1:2022(E)
8.5.5 Verification related to water-tightness . 24
8.6 Restorability verification . 24
8.6.1 General . 24
8.6.2 Structural details related to seismic performance . 25
8.7 Structural details . 25
9 Execution .25
9.1 General . 25
9.2 Construction plan . 25
9.3 Construction . 26
9.4 Inspection . 26
10 Records . .26
11 Maintenance .27
Annex A (informative) Examples of test and design method .28
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ISO/DIS 5091-1:2022(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
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 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 Organisation (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 7, Maintenance and repair of concrete structures.
A list of all parts in the ISO 5091 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
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ISO/DIS 5091-1:2022(E)
Introduction
As a repairing and strengthening method, attaching of cementitious material layer to surface of
existing concrete structures has been widely accepted. Since the cementitious layer does not have
enough tensile strength, tension reinforcement is generally placed in the cementitious layer. There are
two types of attaching way. For the first way, the cementitious layer is attached either on top surface
or bottom surface of horizontal concrete members, especially slabs, while, for the second way, the
cementitious layer is attached to jacket vertical concrete members, especially columns. There has not
been ISO standard on design, execution and maintenance for this method with attaching cementitious
layer. This ISO 5091 serves as the first ISO standard for the intervention by attaching cementitious
material layer with tension reinforcement inside.
At the same time, this ISO 5091 is the first ISO standard developed for a specific intervention method,
which conforms to the umbrella code, ISO 16311 Maintenance and repair of concrete structures,
especially ISO 16311-3 – Part 3: Design of repairs and prevention and ISO 16311-4 – Part 4: Execution of
repairs and prevention.
ISO 5091 Structural intervention of existing concrete structures using cementitious materials consists
of four parts; ISO 5091-1 – Part 1: General principles, ISO 5091-2 – Part 2: Top-surface overlaying,
ISO 5091-3 – Part 3: Bottom-surface (soffit) underlaying, and ISO 5091-4 – Part 4: Jacketing. ISO 5091-1
provides the issues common to all three parts, while ISO 5091-2, 3 and 4 provide the issues specific to
each attaching way of cementitious material layers.
It is expected that this ISO 5091 could serve as a practical standard for construction industry, such as
client, design consultant and general contractor, to apply the structural intervention with externally
attached cementitious layer. Additional technical information, which is not provided explicitly in
ISO 5091, needs to be provided in each application case with consideration of the provisions of ISO 5091.
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DRAFT INTERNATIONAL STANDARD ISO/DIS 5091-1:2022(E)
Structural intervention of existing concrete structures
using cementitious materials —
Part 1:
General principles
1 Scope
This document specifies the standards for design, construction and maintenance following completion
of intervention that is to be applied for performing intervention work using cementitious materials to
improve the performance of existing concrete structures. The intervention dealt with in this guideline
is intended to restore, sustain or improve the mechanical performance of concrete structures. When
the intervention is aimed at restoring or improving durability, reference should be made to relevant
documents.
This document covers the overlaying, underlaying and jacketing methods using cementitious materials.
Assuming that the standard requirements regarding the intervention of existing structures are as
set forth in ISO 16311, especially Parts 3 and 4, this document consists of Part 1: General principles
specifying the common requirements not dependent on the method of performing intervention using
cementitious materials and method-specific Parts 2, 3, and 4, each describing the specifics of top-
surface overlaying, bottom-surface (soffit) underlaying and jacketing, respectively.
The intervention with cementitious materials shallis covered in Clause 4 Basis of maintenance and
repair of ISO 16311-1.
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 16311-1:2014, Maintenance and repair of concrete structures — Part 1: General principles
ISO 16311-2:2014, Maintenance and repair of concrete structures — Part 2: Assessment of existing concrete
structures
ISO 16311-3:2014, Maintenance and repair of concrete structures — Part 3: Design of repairs and
prevention
ISO 16311-4:2014, Maintenance and repair of concrete structures — Part 4: Execution of repairs and
prevention
ISO 19338:2014, Performance and assessment requirements for design standards on structural concrete
ISO 1920-8, Testing of concrete — Part 8: Determination of drying shrinkage of concrete for samples
prepared in the field or in the laboratory
ISO 10406-2, Fibre-reinforced polymer (FRP) reinforcement of concrete — Test methods — Part 2: FRP
sheets
ISO 10406-3, Fibre-reinforced polymer (FRP) reinforcement of concrete — Test methods — Part 3: CFRP
strips
1
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ISO/DIS 5091-1:2022(E)
ISO 12473, General principles of cathodic protection in seawater
ISO 13823, General principles on the design of structures for durability
ISO 14484, Performance guidelines for design of concrete structures using fibre-reinforced polymer (FRP)
materials
ISO 22966, Execution of concrete structures
3 Terms and definitions
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
Top-surface overlaying
A method in which the thickness of the structural element associated with the top surface of the existing
concrete members is increased using cementitious materials, which will generally be reinforced. The
technique enhances the performance (e.g. strength, stiffness) of the existing concrete structure and is
applicable to highway bridge decks, etc.
3.2
Bottom-surface (soffit) underlaying
A method in which the thickness of the structural element associated with the bottom surface of the
existing concrete is increased using cementitious materials, which will generally be reinforced. The
technique enhances the performance (e.g. strength, stiffness) of the existing concrete structure and is
applicable to highway bridge decks, tunnel linings, box culverts / waterway structures, beams, etc.
3.3
Jacketing
A method in which additional cementitious materials and associated reinforcement are added to the
periphery of the existing concrete member to increase its strength, stiffness and/or ductility (applicable
to columns, bridge piers, rigid-frame pier beams, etc.)
3.4
thickening capability
ability to achieve the required application thickness of one layer of polymer hydraulic cement mortar or
other mortar material
3.55
bonding product
material, such as a primer, anchor grouting material or adhesive, that is applied or grouted to bond
concrete members, concrete and mortar or concrete and reinforcing material
3.6
filling material
material injected to fill the gap between a reinforcing material, such as intermediate penetrating tie,
and concrete
3.7
filling property
degree of filling of cracks and adhesion of crack filling material to substrate
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ISO/DIS 5091-1:2022(E)
3.8
intermediate penetrating tie
reinforcing member, generally made of steel or FRP, that is installed inside the drilled hole and glued
into the concrete substrate to improve the ductility and shear strength of bridge piers
3.9
very high early strength cement
type of cement with a typical mix proportion that develops a compressive strength as high as 20 N/
2 2
mm to 30 N/mm within 2 to 3 hours of placement
3.10
reinforcing material
steel or FRP reinforcing material used to sustain the performance of a structure or to restore or
improve performance
3.11
polymer hydraulic cement mortar
hydraulic mortar modified by the addition of a polymer
3.12
overlaying or underlaying material
cementitious material, potentially reinforced, added to an existing concrete structure for the purpose
of making an intervention to enhance the performance of that structure
Note 1 to entry: The top-surface overlay / bottom-surface (soffit) underlay shall achieve adequate bond to the
existing concrete substrate.
3.13
FRP grid
resin-impregnated FRP reinforcing materials formed into a grid shape
3.14
design response value
value of structural response obtained by numerical analysis on design process, such as sectional force
and deformation
3.15
design limit value
design value for quantified limit state on design process, such as strength of element, allowable crack
width
3.16
verification index
representative items to be quantitatively verified by design response value and design limit value on
design process, such as deflection, crack width and strength
3.17
cross section failure
failure which is related to cross sectional strength, such as flexure, shear and axial strength
3.18
maintainability
ability of a structure to meet service objectives with a minimum expenditure of maintenance effort
under service conditions in which maintenance and repair are performed
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ISO/DIS 5091-1:2022(E)
4 Investigation of existing structure
4.1 General
The existing structure for which intervention is to be considered shall be investigated in detail to
obtain the information necessary for intervention design and construction.
4.2 Investigation
4.2.1 Investigation using documents, records, etc.
When an investigation is conducted using documents, records, etc., the climatic conditions,
environmental conditions, geographical conditions and other relevant conditions of the local site shall
be understood in detail from the following viewpoints:
— formulation of material and structural plans;
— formulation of a construction plan; and
— maintenance following completion of intervention.
NOTE Generally, the workability and hardening characteristics of cementitious materials greatly change
depending on the construction environment, such as temperature and, therefore, it is necessary to see the
climate of the local site during the period when construction is planned to be performed. Also, intervention using
cementitious materials requires that the restrictions of the local site regarding the construction space as well
as the carry-in and installation of materials and equipment be understood before a specific construction plan is
formulated.
4.2.2 On-site investigation
On the site, an investigation shall be conducted to check degradation, damage and initial defects of the
existing concrete structure from the following viewpoints:
— Securing of integrity between the existing parts and strengthening parts
— Prediction of durability and degradation after intervention
NOTE In obtaining the expected effect of intervention using cementitious materials, integrity between
the repairing or strengthening parts and existing structure is important. Ensuring integrity requires taking
necessary measures based on the understanding of degradation, such as carbonation of the surface of the
existing structure, damage such as cracks, splash or leakage of water, etc.
Degradation of a concrete structure after intervention progresses at a different rate depending on the type of
cause and degree of degradation. Therefore, before intervention is performed for a damaged concrete structure,
it is necessary to understand the cause and degree of degradation.
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5 Intervention design
5.1 General
In intervention, a rational structural plan shall be formulated and structural details shall be established
based on that plan so that the structure after intervention fulfills the required performance throughout
the remaining design service life.
NOTE The intervention design involves establishing a structural plan and structural details to ensure that
interve
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