ISO 5091-4:2023

Structural intervention of existing concrete structures using cementitious materials — Part 4: Jacketing

This document specifies the standard requirements regarding design, construction and maintenance to be applied for structural intervention using the jacketing method, which places reinforcing materials such as reinforcing steel or fibre-reinforced polymer (FRP) grids around the periphery of existing concrete column or beam and jackets these members with cementitious materials. This document specifies structural intervention of existing concrete structures using cementitious materials design and execution principles, and strategies for defects and on-going deterioration including, but not limited to: a) mechanical actions, e.g. fatigue, impact, overloading, movement caused by settlement, blast, vibration, and seismic actions; b) chemical and biological actions from environments, e.g. sulfate attack, alkali-aggregate reaction; c) physical actions, e.g. freeze–thaw, thermal cracking, moisture movement, salt crystallization, fire, and erosion; d) reinforcement corrosion; e) original construction defects that remained unaddressed from the time of construction.

Intervention structurelle sur les structures en béton existantes utilisant des matériaux cimentaires — Partie 4: Chemisage

General Information

• Status: Published
• Publication Date: 20-Jul-2023
• ICS: 91.080.40 - Concrete structures
• Technical Committee: ISO/TC 71/SC 7 - Maintenance and repair of concrete structures
• Drafting Committee: ISO/TC 71/SC 7 - Maintenance and repair of concrete structures
• Current Stage: 6060 - International Standard published
• Start Date: 21-Jul-2023
• Due Date: 18-Jun-2023
• Completion Date: 21-Jul-2023

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 5091-4
First edition
2023-07
Structural intervention of
existing concrete structures using
cementitious materials —
Part 4:
Jacketing
Intervention structurelle sur les structures en béton existantes
utilisant des matériaux cimentaires —
Partie 4: Chemisage
Reference number
ISO 5091-4:2023(E)
© ISO 2023

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ISO 5091-4:2023(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: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
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ISO 5091-4:2023(E)
Contents Page
Foreword .v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Investigation of existing structure.2
4.1 General . 2
4.2 Investigation . 2
4.2.1 Investigation using documents, records . 2
4.2.2 On-site investigation . 3
5 Intervention design. 3
5.1 General . 3
5.2 Structural plan . 3
5.3 Structural details . 3
6 Materials . 4
6.1 General . 4
6.2 Materials in existing structure . 4
6.3 Materials used in repairing or strengthening parts . 4
6.3.1 General . 4
6.3.2 Cementitious materials . 5
6.3.3 Reinforcing materials . 6
6.3.4 Bonding products . 6
6.3.5 Filling materials . 7
6.4 Characteristic values and design values of materials . 7
6.4.1 General . 7
6.4.2 Cementitious materials . 7
6.4.3 Reinforcing materials . 7
6.4.4 Bonding products . 7
7 Actions . 7
7.1 General . 7
7.2 Actions for intervention design . 7
8 Performance verification for repaired or strengthened structure .7
8.1 General . 7
8.2 Calculation of response values . 8
8.2.1 General . 8
8.2.2 Modelling of structure. 8
8.2.3 Structural analysis . 8
8.2.4 Calculation of response . 8
8.3 Durability verification . 8
8.4 Safety verification . 8
8.4.1 General . 8
8.4.2 Verification related to failure . 9
8.5 Serviceability verification . 10
8.5.1 General . 10
8.5.2 Verification related to appearance . 10
8.5.3 Verification related to vibration . 10
8.5.4 Verification related to displacement and deformation . 10
8.6 Seismic performance verification. 10
8.7 Structural details . 10
8.7.1 Arrangement of reinforcing materials and spacing of reinforcing steel . 10
8.7.2 Covering and jacketing thickness of reinforcing materials. 11
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ISO 5091-4:2023(E)
8.7.3 Joints for lateral reinforcing materials . 11
8.7.4 Anchorage of longitudinal reinforcement to footings . 11
8.7.5 Intermediate penetrating tie . 11
9 Construction .11
9.1 General . 11
9.2 Prior investigation and construction plan.12
9.3 Surface treatment . 13
9.4 Assembly of reinforcing materials . 13
9.5 Execution of concrete jacketing . 14
9.6 Execution of mortar jacketing . 14
9.6.1 Surface preparation . 14
9.6.2 Storage, mixing and transportation of jacketing materials . 14
9.6.3 Execution of mortar jacketing . 14
9.6.4 Curing . 14
9.7 Surface protection . 15
9.8 Quality control . 15
9.9 Inspection . 15
10 Records . .15
11 Maintenance .15
Annex A (informative) Examples of design and execution .16
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ISO 5091-4:2023(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 5091-4:2023(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 any ISO
standard on design, execution and maintenance for this method with attaching cementitious layer. The
ISO 5091 series serves as the first ISO standard for the intervention by attaching 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 jacketing is cases of intervention in which the jacketing method is used to repair or strengthen
concrete structures such as reinforced concrete bridge piers damaged by seismic actions. When
a damaged concrete structure is repaired or strengthened using the jacketing method, the status of
damage such as concrete cracking and spalling are grasped through a prior investigation and crack
injection or sealing, patching repair and other measures are taken in advance as necessary.
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 5091-4:2023(E)
Structural intervention of existing concrete structures
using cementitious materials —
Part 4:
Jacketing
1 Scope
This document specifies the standard requirements regarding design, construction and maintenance
to be applied for structural intervention using the jacketing method, which places reinforcing materials
such as reinforcing steel or fibre-reinforced polymer (FRP) grids around the periphery of existing
concrete column or beam and jackets these members with cementitious materials.
This document specifies structural intervention of existing concrete structures using cementitious
materials design and execution principles, and strategies for defects and on-going deterioration
including, but not limited to:
a) mechanical actions, e.g. fatigue, impact, overloading, movement caused by settlement, blast,
vibration, and seismic actions;
b) chemical and biological actions from environments, e.g. sulfate attack, alkali-aggregate reaction;
c) physical actions, e.g. freeze–thaw, thermal cracking, moisture movement, salt crystallization, fire,
and erosion;
d) reinforcement corrosion;
e) original construction defects that remained unaddressed from the time of construction.
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 5091-1:2023, Structural intervention of existing concrete structures using cementitious materials —
Part 1: General principles
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/
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ISO 5091-4:2023(E)
3.1
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.
3.2
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.
3.3
filling material
material injected to fill the gap between a reinforcing material, such as intermediate penetrating tie,
and concrete
3.4
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
3.5
reinforcing material
steel or FRP material used to sustain, restore or improve the mechanical performance of a structure
3.6
polymer hydraulic cement mortar
hydraulic composition made cementitious materials and fine aggregate modified by the addition of a
polymer
3.7
FRP grid
resin-impregnated FRP reinforcing materials formed into a grid shape
4 Investigation of existing structure
4.1 General
The investigation of the existing structure for which to consider intervention using the jacketing
method shall be conducted as set forth in ISO 5091-1:2023, Clause 4.
When an earthquake-affected structure is repaired or strengthened using the jacketing method, the
status of damage to that structure shall be studied in detail.
4.2 Investigation
4.2.1 Investigation using documents, records
An investigation using documents, records, etc. shall be conducted in accordance with ISO 5091-1:2023,
4.2.1.
Details of the materials used in the target existing structure and the structural specifications shall be
understood from the design documents created at the time of construction, the design documents for
the intervention work performed before the consideration of intervention.
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ISO 5091-4:2023(E)
4.2.2 On-site investigation
The on-site investigation on the existing structure shall be conducted in accordance with
ISO 5091-1:2023, 4.2.2. Specifically, an earthquake-affected structure shall involve studying the status
of damage caused by the earthquake in detail.
In the structural performance evaluation based on the appearance changes, the grades of structural
performance shall be established on mechanical grounds taking into full consideration the degree
of each graded appearance change and the impact of the changed region on structural performance.
Appearance changes can be classified into the following three grades.
— Grade I: No or minor damage
— Grade II: Moderate damage
— Grade III: Severe damage
The mechanical resistance of the change region should be classified into the following four levels.
— Level a: Resistance remaining intact
— Level b: Slightly degraded resistance
— Level c: Significantly degraded resistance
— Level d: No resistance
5 Intervention design
5.1 General
In the intervention design using the jacketing method, a rational structural plan shall be formulated,
and structural details shall be established based on that plan so that the structure after intervention
fulfils the required performance throughout the remaining design service life.
When an earthquake-affected structure is repaired or strengthened using the jacketing method,
it is necessary to take appropriate measures for the members damaged by the earthquake first. The
intervention plan shall be considered.
5.2 Structural plan
In the intervention plan using the jacketing method, the intervention method shall be selected,
taking into consideration the structural properties, materials, construction method and restrictions,
maintenance method, economy to ensure that the required performance is fulfilled under the
environmental conditions of the structure, factoring in the structure’s importance.
In the design phase, it can be considered that the public safety requirements regarding the spalling off
of the jacketing part and other public disaster risks for users of the structure, third parties, etc. are met
if the requirements set forth in 8.3 are met.
5.3 Structural details
In intervention using the jacketing method, structural details shall be determined so as to ensure the
integrity between the existing members and jacketing parts.
The members to be repaired or strengthened using the jacketing method, the range of intervention, the
arrangement of reinforcing materials around the periphery of the existing members, the thicknesses of
reinforcing material covering and jacketing material, etc. shall be established appropriately so that the
performance requirements of the structure are met.
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ISO 5091-4:2023(E)
If the flexural load-carrying capacity needs to be improved, the reinforcement placed around the
periphery shall be anchored securely enough to the existing parts.
If the ductility needs to be improved, it is advisable to consider placing intermediate penetrating tie
according to the cross-sectional shape of the existing structure.
6 Materials
6.1 General
The materials used for jacketing shall be of proven quality to ensure that the required performance is
fulfilled for a necessary period. Specifically, for jacketing for the seismic strengthening of an existing
structure, materials shall be selected to ensure the integrity between the existing parts and jacketing
parts so that the structure repaired or strengthened through jacketing fulfils the seismic performance.
6.2 Materials in existing structure
The characteristic values of material strength, design values and material factors of the materials in an
existing and earthquake-affected structure shall be determined in accordance with ISO 5091-1:2023,
6.2.
When intervention is targeted at an earthquake-affected structure, the materials in the existing
structure can have incurred severe damage, such as yielding or buckling of reinforcing steel, cracking of
concrete or crushing of core concrete, and the impact of that damage shall be evaluated appropriately.
If any measure such as cracking repair or patching repair has been taken for such damage prior to
intervention through jacketing, the characteristic values, design values and material factors of the
materials in the existing part shall be determined, appropriately taking into consideration the influence
of that measure as necessary.
6.3 Materials used in repairing or strengthening parts
6.3.1 General
The quality of the materials used in the parts repaired or strengthened through jacketing shall be as set
forth in ISO 5091-1:2023, 6.3.
Table 1 shows the classification of the materials used for jacketing. In this document, they refer to the
following materials.
— Primer used to improve the bond strength of the existing concrete and mortar.
— Anchor grouting material used to anchor longitudinal reinforcement or other reinforcing materials
to footings.
— Adhesive used to bond reinforcing materials and existing concrete. It is mainly used for a construction
method that requires a bond for reinforcing materials placed in grooves on existing concrete cover
or for bonding intermediate penetrating tie.
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ISO 5091-4:2023(E)
Table 1 — Types of materials used for jacketing
Construction Cementitious mate- Reinforcing materials Bonding products Filling mate-
method rials rials
— Reinforcing steel
— Prestressing steel
— Primer
Concrete jacketing — Concrete
— Non-shrink
— FRP reinforcing
— Anchor grouting
grout
materials
material
— Mortar
— Reinforcing steel
— Adhesive
Mortar jacketing — Mortar
— FRP reinforcing
materials
6.3.2 Cementitious materials
The cementitious materials use
...

DRAFT INTERNATIONAL STANDARD
ISO/DIS 5091-4
ISO/TC 71/SC 7 Secretariat: KATS
Voting begins on: Voting terminates on:
2022-07-26 2022-10-18
Structural intervention of existing concrete structures
using cementitious materials —
Part 4:
Jacketing
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 5091-4:2022(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 5091-4:2022(E)
DRAFT INTERNATIONAL STANDARD
ISO/DIS 5091-4
ISO/TC 71/SC 7 Secretariat: KATS
Voting begins on: Voting terminates on:

Structural intervention of existing concrete structures
using cementitious materials —
Part 4:
Jacketing
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: [phone]
WHICH REFERENCE MAY BE MADE IN
Reference number
Email: [e-mail]
NATIONAL REGULATIONS.
Website: www.iso.org ISO/DIS 5091-4:2022(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 5091-4:2022(E)
Contents Page
Foreword .v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
3.1 General . 2
4 Investigation of existing structure.2
4.1 General . 2
4.2 Investigation . 2
4.2.1 Investigation using documents, records, etc. . 2
4.2.2 On-site investigation . 3
5 Intervention design. 4
5.1 General . 4
5.2 Structural plan . 4
5.3 Structural details . 5
6 Materials . 6
6.1 General . 6
6.2 Materials in existing structure . 6
6.3 Materials used in repairing or strengthening parts . 6
6.3.1 General . 6
6.3.2 Cementitious materials . 7
6.3.3 Reinforcing materials . 9
6.3.4 Bonding products . 9
6.3.5 Filling materials . 10
6.4 Characteristic values and design values of materials . 10
6.4.1 eneral . 10
6.4.2 Cementitious materials . 10
6.4.3 Reinforcing materials . 10
6.4.4 Bonding products . 10
7 Actions .10
7.1 General . 10
7.2 Actions for intervention design . 11
8 Performance verification for repaired or strengthened structure .11
8.1 General . 11
8.2 Calculation of response values . 11
8.2.1 General . 11
8.2.2 Modeling of structure .12
8.2.3 Structural analysis .12
8.2.4 Calculation of response .12
8.3 Durability verification .13
8.4 Safety verification . 13
8.4.1 General .13
8.4.2 Verification related to failure . 13
8.5 Serviceability verification . 16
8.5.1 General . 16
8.5.2 Verification related to appearance . 17
8.5.3 Verification related to vibration . 17
8.5.4 Verification related to displacement and deformation . 17
8.6 Seismic performance verification. 17
8.7 Structural details . 18
8.7.1 Arrangement of reinforcing materials and spacing of reinforcing steel . 18
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ISO/DIS 5091-4:2022(E)
8.7.2 Covering and jacketing thickness of reinforcing materials. 18
8.7.3 Joints for lateral reinforcing materials . 19
8.7.4 Anchorage of longitudinal reinforcement to footings . 19
8.7.5 Intermediate penetrating tie . 20
9 Construction .20
9.1 General . 20
9.2 Prior investigation and construction plan. 21
9.3 Surface treatment . 22
9.4 Assembly of reinforcing materials . 22
9.5 Execution of concrete jacketing . 23
9.6 Execution of mortar jacketing . 23
9.6.1 Surface preparation . 23
9.6.2 Storage, mixing and transportation of jacketing materials .23
9.6.3 Execution of mortar jacketing . 24
9.6.4 Curing . 24
9.7 Surface protection . 25
9.8 Quality control . 25
9.9 Inspection . 25
10 Records . .26
11 Maintenance .26
Annex A (informative) Examples of execution and design .27
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ISO/DIS 5091-4:2022(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 5091-4:2022(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 5091-4:2022(E)
Structural intervention of existing concrete structures
using cementitious materials —
Part 4:
Jacketing
1 Scope
This document specifies the standard requirements regarding design, construction and maintenance
to be applied for structural intervention using the jacketing method, which places reinforcing materials
such as reinforcing steel or FRP grids around the periphery of existing concrete column or beam and
jackets these members with cementitious materials. The requirements not mentioned in the Jacketing
shall be as set forth in ISO / NP 5091-1.
NOTE Jacketing is a construction method that restores or improves mechanical performance, such as flexural
load-carrying capacity, shear capacity and ductility, as well as durability and other performance properties, by
placing reinforcing steel or FRP grids around existing concrete members or in the grooves on the concrete surface
and jacketing the entire periphery of the members with cementitious materials, such as concrete or polymer
hydraulic cement mortar, so that the materials integrate with the existing concrete members. Generally, when
concrete is used as the jacketing material, the concrete jacketing method is adopted whereby concrete is placed
in set up molds, or when polymer hydraulic cement mortar or other types of mortar is used as the jacketing
material, the mortar jacketing method is adopted whereby the thickness of members is increased by spraying or
trowelling. Jacketing is often employed for seismic strengthening mainly of column members such as bridge piers
and beam members of rigid-frame piers. The Jacketing specifies the standard requirements regarding design,
construction and maintenance to be applied for structural intervention of existing concrete structures using the
jacketing method. The requirements not mentioned in the Jacketing shall be as set forth in ISO / NP 5091-1.
NOTE The Jacketing also covers cases of intervention in which the jacketing method is used to repair or
strengthen concrete structures such as reinforced concrete bridge piers damaged by seismic actions. When a
damaged concrete structure is repaired or strengthened using the jacketing method, the status of damage such
as concrete cracking and spalling shall be grasped through a prior investigation and crack injection or sealing,
patching repair and other measures shall be taken in advance as necessary
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 22966:2009, Execution of concrete structures
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ISO/DIS 5091-4:2022(E)
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 General
The definitions of the terms used in the Jacketing shall be as defined in Clause 3 of ISO / NP 5091-1.
4 Investigation of existing structure
4.1 General
The investigation of the existing structure for which to consider intervention using the jacketing
method shall be conducted as set forth in Clause 4 of ISO / NP 5091-1.
When an earthquake-affected structure is repaired or strengthened using the jacketing method, the
status of damage to that structure shall be studied in detail.
NOTE Jacketing is often employed for seismic strengthening of vertical members such as reinforced concrete
bridge piers. In some cases, it is also used for intervention of earthquake-affected structures. An earthquake-
affected structure may have been suffered from with different types of damage including cracking of concrete,
spalling of cover concrete, crushing of concrete, buckling and rupture of reinforcing steel and so on. Depending
on the status of damage, it may be necessary to take measures such as crack injection or sealing, patching repair,
restoration of deformation of reinforcement and replacement of reinforcement before intervention using the
jacketing method. These types of damage may significantly impact the mechanical performance of the existing
structure and the repaired or strengthened structure. Therefore, when an earthquake-affected structure is
repaired or strengthened using the jacketing method, it is necessary to grasp the status of damage through an
investigation, evaluate the impact that these types of damage have on the performance of the structure by means
of an appropriate method and ensure that the intervention design and construction plan reflect the evaluation
results.
4.2 Investigation
4.2.1 Investigation using documents, records, etc.
A investigation using documents, records, etc. shall be conducted in accordance with 4.2.1 of ISO / NP
5091-1.
Details of the materials used in the target existing structure and the structural specifications shall be
understood from the design documents created at the time of construction, the design documents for
the intervention work performed before the consideration of intervention.
NOTE The structural specifications mean the cross-sectional dimensions and reinforcement arrangement.
These are necessary for evaluating the performance of the existing structure and verifying the performance of
the repaired or strengthened structure.
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ISO/DIS 5091-4:2022(E)
4.2.2 On-site investigation
The on-site investigation on the existing structure shall be conducted in accordance with 4.2.2 of ISO /
NP 5091-1.
NOTE Obtaining the expected effect of intervention through the use of the jacketing method requires
ensuring the integrity between the existing structure and the jacketing parts. It is therefore advisable to grasp
the status of degradation and damage on the surface and inside of the existing structure through the on-site
investigation.
The on-site investigation on an earthquake-affected structure shall involve studying the status of
damage caused by the earthquake in detail.
NOTE An earthquake-affected structure may have been suffered from different types of damage including
cracking of concrete, spalling of cover concrete, crushing of concrete, buckling and rupture of reinforcing steel
and so on. Therefore, when an earthquake-affected structure is repaired or strengthened using the jacketing
method, the status of damage shall be studied in detail by means of an appropriate method. The methods
commonly used in the on-site investigation are visual inspection and tapping inspection.
NOTE It is advisable to grade the changes in the appearance, taking into consideration the degree of damage
to the concrete, steel, etc. and changes in the mechanical performance, and evaluate the structural performance
according to the grading of the appearance changes. In the structural performance evaluation based on the
appearance changes, the grades of structural performance shall be established on mechanical grounds taking
into full consideration the degree of each graded appearance change and the impact of the changed region on
structural performance. Appearance changes may be classified into the following three grades.
— Grade I: No or minor damage
— Grade II: Moderate damage
— Grade III: Severe damage
The mechanical resistance of the change region should be classified into the following 4 levels.
— Level a: Resistance remaining intact
— Level b: Slightly degraded resistance
— Level c: Significantly degraded resistance
— Level d: No resistance
NOTE As for reinforced concrete bridge piers damaged by an earthquake, the methods of inspecting the
damaged bridge piers and determining the degree of damage should be set properly. In the case of reinforced
concrete bridge piers, both the position and degree of damage are important. It is, therefore, necessary to
investiga
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