ISO/TS 21056:2025

Recycled aggregate concrete — Additional provisions and guidance for specification, performance, production and execution

This document provides principles and a framework for the specification, performance, production and execution of recycled aggregate concrete (RAC). This document applies to concrete for structures cast in situ, pre-cast structures and non-structural concrete. The concrete can be mixed on site, ready-mixed concrete or produced in a plant for pre-cast concrete products.

Béton de granulats recyclés — Dispositions et recommandations supplémentaires pour la spécification, la performance, la production et l'exécution

General Information

• Status: Published
• Publication Date: 13-Aug-2025
• ICS: 91.100.30 - Concrete and concrete products
• Technical Committee: ISO/TC 71/SC 3 - Concrete production and execution of concrete structures
• Drafting Committee: ISO/TC 71/SC 3 - Concrete production and execution of concrete structures
• Current Stage: 6060 - International Standard published
• Start Date: 14-Aug-2025
• Due Date: 25-May-2025
• Completion Date: 14-Aug-2025

Standards Content (Sample)

Technical
Specification
ISO/TS 21056
First edition
Recycled aggregate concrete —
2025-08
Additional provisions and guidance
for specification, performance,
production and execution
Béton de granulats recyclés — Dispositions et recommandations
supplémentaires pour la spécification, la performance, la
production et l'exécution
Reference number
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols and abbreviated terms. 3
5 Constituent materials . 3
5.1 Requirements .3
5.1.1 Recycled coarse aggregate .3
5.1.2 Recycled fine aggregate .3
5.1.3 Other constituent materials .3
5.2 Quality inspection of recycled aggregate .4
5.3 Storage and transportation of recycled aggregate .4
6 Performance of recycled aggregate concrete . 4
6.1 Consistence .4
6.2 Mechanical property .4
6.2.1 Strength .4
6.2.2 Elastic modulus .5
6.3 Drying shrinkage and creep .5
6.4 Carbonation resistance .5
6.5 Permeability .5
6.6 Chloride resistance .6
6.7 Thermal parameters .6
6.8 Alkali-silica reactivity.6
7 Mix proportion of recycled aggregate concrete . 6
7.1 General .6
7.2 Determination of target compressive strength .6
7.3 Determination of water content for recycled aggregate concrete .7
7.4 Determination of cementitious material content .8
7.5 Determination of coarse and fine aggregate content.8
8 Production of recycled aggregate concrete . 8
8.1 Preparation .8
8.2 Mixing recycled aggregate concrete .8
9 Delivery and transportation of recycled aggregate concrete . 8
9.1 Delivery of ready-mixed fresh concrete .8
9.2 Transportation of ready-mixed fresh concrete .9
10 Execution of recycled aggregate concrete . 9
10.1 Pumping . .9
10.2 Casting and curing .9
Annex A (informative) Application guideline of recycled aggregate concrete .10
Annex B (informative) Method for determining w/c ratio of recycled aggregate concrete .11
Bibliography .13

iii
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 3, Concrete production and execution of 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
Introduction
With the development of the construction industry, the wastes from the construction phase and the
demolition phase (often called the construction and demolition wastes) are increasing. The landfill of
the construction and demolition wastes will cause the shortage of available land area and environmental
pollution. After being crushed and sorted, the construction and demolition wastes can be upcycled in the
form of recycled aggregates. Recycled aggregate concrete can be produced by substituting all or part of
natural aggregates with recycled aggregates. Recycled aggregate concrete can reduce the amount of the
construction and demolition wastes as well as alleviate the consumption of natural aggregates through the
use of recycled aggregates. In addition, it can reduce landfill area and environmental impact. As a result,
recycled aggregate concrete has become the subject of growing interest. Its primary objective is to promote
the use of recycled aggregates, which are produced from construction and demolition wastes, in structural
and non-structural concrete.
The properties of recycled aggregates are different from those of natural aggregates, resulting in the
variation of mix proportion, consistence, strength, deformation, durability between recycled aggregate
concrete and natural aggregate concrete. This technical specification is primarily concerned with promoting
the application of recycled aggregate concrete and provides additional provisions for ISO 22965 to address
the differences between recycled aggregate concrete and natural aggregate concrete.
The relationship of this document (TS 21056) with other International Standards is shown in Fig 1.
Key
information flow: standard A provides information to standard B
hierarchy: standard B complements standard A
Figure 1 — Relationship of this document to other International Standards

v
Technical Specification ISO/TS 21056:2025(en)
Recycled aggregate concrete — Additional provisions and
guidance for specification, performance, production and
execution
1 Scope
This document provides principles and a framework for the specification, performance, production and
execution of recycled aggregate concrete (RAC).
This document applies to concrete for structures cast in situ, pre-cast structures and non-structural
concrete. The concrete can be mixed on site, ready-mixed concrete or produced in a plant for pre-cast
concrete products.
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
...

FINAL DRAFT
Technical
Specification
ISO/DTS 21056
ISO/TC 71/SC 3
Recycled aggregate concrete —
Secretariat: SN
Additional provisions and guidance
Voting begins on:
for specification, performance,
2025-05-19
production and execution
Voting terminates on:
2025-07-14
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 SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
ISO/DTS 21056:2025(en) © ISO 2025

FINAL DRAFT
ISO/DTS 21056:2025(en)
Technical
Specification
ISO/DTS 21056
ISO/TC 71/SC 3
Recycled aggregate concrete —
Secretariat: SN
Additional provisions and guidance
Voting begins on:
for specification, performance,
production and execution
Voting terminates on:
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 SUPPOR TING DOCUMENTATION.
© ISO 2025
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
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 Reference number
ISO/DTS 21056:2025(en) © ISO 2025

ii
ISO/DTS 21056:2025(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols and abbreviated terms. 3
5 Constituent materials . 3
5.1 Requirements .3
5.1.1 Recycled coarse aggregate .3
5.1.2 Recycled fine aggregate .3
5.1.3 Other constituent materials .3
5.2 Quality inspection of recycled aggregate .4
5.3 Storage and transportation of recycled aggregate .4
6 Performance of recycled aggregate concrete . 4
6.1 Consistence .4
6.2 Mechanical property .4
6.2.1 Strength .4
6.2.2 Elastic modulus .5
6.3 Drying shrinkage and creep .5
6.4 Carbonation resistance .5
6.5 Permeability .5
6.6 Chloride resistance .6
6.7 Thermal parameters .6
6.8 Alkali-silica reactivity.6
7 Mix proportion of recycled aggregate concrete . 6
7.1 General .6
7.2 Determination of target compressive strength .6
7.3 Determination of water content for recycled aggregate concrete .7
7.4 Determination of cementitious material content .8
7.5 Determination of coarse and fine aggregate content.8
8 Production of recycled aggregate concrete . 8
8.1 Preparation .8
8.2 Mixing recycled aggregate concrete .8
9 Delivery and transportation of recycled aggregate concrete . 8
9.1 Delivery of ready-mixed fresh concrete .8
9.2 Transportation of ready-mixed fresh concrete .9
10 Execution of recycled aggregate concrete . 9
10.1 Pumping . .9
10.2 Casting and curing .9
Annex A (informative) Application guideline of recycled aggregate concrete .10
Annex B (informative) Method for determining w/c ratio of recycled aggregate concrete .11
Bibliography .13

iii
ISO/DTS 21056:2025(en)
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 3, Concrete production and execution of 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/DTS 21056:2025(en)
Introduction
With the development of the construction industry, the wastes from the construction phase and the
demolition phase (often called the construction and demolition wastes) are increasing. The landfill of
the construction and demolition wastes will cause the shortage of available land area and environmental
pollution. After being crushed and sorted, the construction and demolition wastes can be upcycled in the
form of recycled aggregates. Recycled aggregate concrete can be produced by substituting all or part of
natural aggregates with recycled aggregates. Recycled aggregate concrete can reduce the amount of the
construction and demolition wastes as well as alleviate the consumption of natural aggregates through the
use of recycled aggregates. In addition, it can reduce landfill area and environmental impact. As a result,
recycled aggregate concrete has become the subject of growing interest. Its primary objective is to promote
the use of recycled aggregates, which is produced from construction and demolition wastes, in structural
and non-structural concrete.
The properties of recycled aggregates are different from those of natural aggregates, resulting in the
variation of mix proportion, consistence, strength, deformation, durability between recycled aggregate
concrete and natural aggregate concrete. This technical specification is primarily concerned with promoting
the application of recycled aggregate concrete and provides additional provisions for ISO 22965 to address
the differences between rec
...

ISO/DTS 21056
ISO/TC 71/SC 3
Secretariat: SN
Date: 2025-05-05
Recycled aggregate concrete — Additional provisions and guidance
for specification, performance, production and execution

ISO/DTS 21056:(en)
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
E-mail: [e-mail]
ISO 19595
Natural aggregates for
ISO 22965-1
concrete
Concrete-Part 1: Method of
specifying and guidance for
the specifier
ISO 18985
Recycled aggregates for ISO 22965-2
concrete
Concrete-Part 2: Specification
of constituent materials,
production of concrete and
TS 21056
compliance of concrete
Recycled aggregate concrete-
Additional provisions and
guidance for specification,
ISO 22966
performance, production and
execution
Website: www.iso.org
Execution of concrete
Legend
Information flow: standard A provides information to standard B
A B
A B Hierarchy: standard B complements standard A
B
Fig. 1
Published in Switzerland
ii
ISO/DTS 21056:(en)
Contents
Foreword . iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols and abbreviated terms . 3
5 Constituent materials . 3
5.1 Requirements . 3
5.2 Quality inspection of recycled aggregate . 4
5.3 Storage and transportation of recycled aggregate . 4
6 Performance of recycled aggregate concrete . 4
6.1 Consistence . 4
6.2 Mechanical property . 4
6.3 Drying shrinkage and creep . 5
6.4 Carbonation resistance . 5
6.5 Permeability . 6
6.6 Chloride resistance . 6
6.7 Thermal parameters . 6
6.8 Alkali-silica reactivity . 6
7 Mix proportion of recycled aggregate concrete . 6
7.1 General. 6
7.2 Determination of target compressive strength . 7
7.3 Determination of water content for recycled aggregate concrete . 8
7.4 Determination of cementitious material content . 8
7.5 Determination of coarse and fine aggregate content . 8
8 Production of recycled aggregate concrete . 8
8.1 Preparation . 8
8.2 Mixing recycled aggregate concrete . 8
9 Delivery and transportation of recycled aggregate concrete . 9
9.1 Delivery of ready-mixed fresh concrete . 9
9.2 Transportation of ready-mixed fresh concrete . 9
10 Execution of recycled aggregate concrete. 9
10.1 Pumping . 9
10.2 Casting and curing . 9
Annex A (informative) Application guideline of recycled aggregate concrete . 10
Annex B (informative) Method for determining w/c ratio of recycled aggregate concrete . 12
Bibliography . 14

iii
ISO/DTS 21056:(en)
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 3, Concrete production and execution of 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/DTS 21056:(en)
Introduction
With the development of the construction industry, the wastes from the construction phase and the demolition
phase (often called the construction and demolition wastes) are increasing. The landfill of the construction
and demolition wastes will cause the shortage of available land area and environmental pollution. After being
crushed and sorted, the construction and demolition wastes can be upcycled in the form of recycled
aggregates. Recycled aggregate concrete can be produced by substituting all or part of natural aggregates with
recycled aggregates. Recycled aggregate concrete can reduce the amount of the construction and demolition
wastes as well as alleviate the consumption of natural aggregates through the use of recycled aggregates. In
addition, it can reduce landfill area and environmental impact. As a result, recycled aggregate concrete has
become the subject of growing interest. Its primary objective is to promote the use of recycled aggregates,
which is produced from construction and demolition wastes, in structural and non-structural concrete.
The properties of recycled aggregates are different from those of natural aggregates, resulting in the variation
of mix proportion, consistence, strength, deformation, durability between recycled aggregate concrete and
natural aggregate concrete. This technical specification is primarily concerned with promoting the application
of recycled aggregate concrete and provides additional provisions for ISO 22965 to address the differences
between recycled aggregate concrete and natural aggregate concrete.
The relationship of this document (TS 21056) with other International Standards is shown in Fig 1.

Key
information flow: standard A provides information to standard B

hierarchy: standard B complements standard A

Figure 1 — Relationship of this document to other International Standards
v
ISO/DTS 21056:(en)
Recycled aggregate concrete — Additional provisions and guidance
for specification, performance, production and execution
1 Scope
This document provides principles and a framework for the specification, performance, production and
execution of recycled aggregate concrete (RAC).
This document applies to concrete for structures cast in situ, pre-cast structures and non-structural concrete.
The concrete can be mixed on site, ready-mixed concrete or produced in a plant for pre-cast concrete products.
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 1920-1, Testing of concrete — Part 1: Sampling of fresh concrete
ISO 1920-2, Testing of concrete — Part 2: Properties of fresh concrete
ISO 1920-4, Testing of concrete — Part 4: Strength of hardened concrete
ISO 1920-5, Density and water penetration depth
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 1920-9, Testing of concrete — Part 9: Determination of creep of concrete cylinders in compression
ISO 1920-10, Testing of concrete — Part 10: Determination of static modulus of elasticity in compression
ISO 1920-11, Testing of concrete — Part 11: Determination of the chloride resistance of concrete, unidirectional
diffusion
ISO 1920-12, Testing of concrete — Part 12: Determination of the carbonation resistance of concrete —
Accelerated carbonation method
ISO 12439, Mixing water for concrete
ISO 18985, Recycled aggregates for concrete
ISO 19595, Natural aggregates for concrete
ISO 19596, Admixtures for concrete
ISO 22904, Additions for concrete
ISO 22965-2, Concrete-Part 2: Specification of constituent materials, production of concrete and compliance of
concrete
ISO 22965-1, Concrete-Part 1: Method of specifying and guidance for the specifier
ISO 22966, Execution of concrete structures
© ISO/CD TS 21056 2025 – All rights reserved
ISO/CD TSDTS 21056:2025:(en)
ASTM C1293, Standard test method for determination of length change of concrete due to alkali-Silica reaction
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
recycled coarse aggregate
Note 1 to entry: recycled concrete aggregate and/or recycled mix aggregate with aggregate size greater than 4,75 mm
[SOURCE: ISO 18985: 2025, 3.2]
3.2
recycled fine aggregate
recycled concrete a
...