ISO 24068-2:2021

Building and civil engineering sealants - Determination of the degree of cure - Part 2: Build-up of tensile and adhesion properties in test joint specimens

This document specifies a method for the determination of the degree of cure of one- and multi-component sealants used in joints as indicated by the build-up of the tensile and adhesion properties in test joint specimens during cure.

Titre manque — Partie 2: Titre manque

General Information

• Status: Published
• Publication Date: 02-May-2021
• ICS: 91.100.50 - Binders. Sealing materials
• Technical Committee: ISO/TC 59/SC 8 - Sealants
• Drafting Committee: ISO/TC 59/SC 8/WG 22 - Cure properties
• Current Stage: 6060 - International Standard published
• Start Date: 03-May-2021
• Due Date: 17-May-2022
• Completion Date: 03-May-2021

Overview - ISO 24068-2:2021 (Building and civil engineering sealants)

ISO 24068-2:2021 specifies a laboratory method for determining the degree of cure of one- and multi-component building and civil engineering sealants by measuring the build-up of tensile and adhesion properties in joint-shaped test specimens during cure. The standard defines specimen preparation, conditioning (reference and test), tensile testing, result calculation and reporting so that users can quantify how far a sealant has cured relative to a agreed reference condition.

Key topics and technical requirements

• Test specimens and substrates: Two substrate supports per specimen; substrate materials selected from mortar, anodized aluminium or glass (ISO 13640 guidance). Spacers of 12 mm × 12 mm and anti-adherent PTFE film are used for specimen assembly.
• Preparation: Sealant and components conditioned at (23 ± 2) °C and (50 ± 10) % RH for minimum 16 h prior to specimen preparation. Follow manufacturer mixing instructions for multi-component products.
• Conditioning (curing):
  • Test specimens: cured at (23 ± 2) °C and (50 ± 10) % RH for selected cure intervals (typical examples: 16 h, 24 h, 48 h, 72 h, 4 d, 7 d, 14 d).
  • Reference specimens: Method A - 28 days at (23 ± 2) °C/50 ± 10 % RH. Method B - Method A followed by three cycles of heat and water exposure (oven at 70 ± 2 °C and distilled water at 23 ± 2 °C).
• Tensile testing: Use a tensile-testing machine with recording device, extending specimens at (5.5 ± 0.5) mm/min until rupture. Record stress–strain curves, secant modulus at chosen elongation (e.g., 100 % or 60 %) and tensile strength (maximum stress).
• Calculations: Degree of cure (%) = (mean property of test specimens / mean property of reference specimens) × 100. Properties can be tensile stress (secant modulus) or tensile strength. Rounding rules and reporting precision follow ISO 80000-1 guidance.
• Sample size & reporting: Minimum three test and three reference specimens per condition. Test report must include specimen details, batch, mix ratio, stress–strain diagrams, conditioning methods and calculated degree of cure.

Applications and who uses it

• Sealant manufacturers: product development, cure profiling, quality control and specification compliance.
• Independent test laboratories: standardized test method for acceptance testing and comparative evaluation.
• Specifiers and contractors: verify cure performance for installation schedules, performance acceptance and warranty claims.
• R&D and formulation scientists: optimize cure rate, adhesion development and mechanical property build-up.

Keywords: ISO 24068-2:2021, building sealants, degree of cure, tensile properties, adhesion properties, test joint specimens, conditioning, tensile testing, reference specimens.

Related standards

• ISO 6927 - Sealants vocabulary
• ISO 8339 - Determination of tensile properties (extension to break)
• ISO 13640 - Specifications for test substrates
• ISO 80000-1 - Quantities and units (rounding and units guidance)

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 24068-2
First edition
2021-05
Building and civil engineering
sealants — Determination of the
degree of cure —
Part 2:
Build-up of tensile and adhesion
properties in test joint specimens
Reference number
©
ISO 2021
© ISO 2021
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
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below or ISO’s member body in the country of the requester.
ISO copyright office
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Phone: [phone]
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Published in Switzerland
ii © ISO 2021 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Apparatus and materials. 2
6 Preparation of test specimen . 4
7 Conditioning of test and reference specimens . 4
7.1 Conditioning of test specimens . 4
7.2 Conditioning of reference specimens . 4
7.2.1 General. 4
7.2.2 Method A . 4
7.2.3 Method B . 5
8 Test procedure . 5
9 Calculation and expression of test result . 5
9.1 Tensile stress (secant modulus) . 5
9.2 Tensile strength . 6
9.3 Degree of cure . 6
9.4 Rounding of results . 6
10 Test report . 6
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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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
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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
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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
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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 59, Buildings and civil engineering works,
Subcommittee SC 8, Sealants.
A list of all parts in the ISO 24068 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.
iv © ISO 2021 – All rights reserved

INTERNATIONAL STANDARD ISO 24068-2:2021(E)
Building and civil engineering sealants — Determination of
the degree of cure —
Part 2:
Build-up of tensile and adhesion properties in test joint
specimens
1 Scope
This document specifies a method for the determination of the degree of cure of one- and multi-
component sealants used in joints as indicated by the build-up of the tensile and adhesion properties in
test joint specimens during cure.
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 6927, Building and civil engineering sealants — Vocabulary
ISO 8339, Building construction — Sealants — Determination of tensile properties (Extension to break)
ISO 13640, Buildings and civil engineering works — Sealants — Specifications for test substrates
ISO 80000-1:2009, Quantities and units — Part 1: General
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 6927 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
4 Principle
The degree of cure of joint-shaped test specimen of a (ambient temperature curing) sealant is
determined as the ratio between the value of engineering tensile stress (secant modulus) and/or
tensile strength at any time during cure and the corresponding value measured after a reference cure
period (conditioning A or B or any other reference cure period or conditions as agreed by the parties
concerned).
5 Apparatus and materials
5.1 Substrate supports, made of substrate materials as defined in ISO 13640, to be selected from
mortar and/or anodized aluminium and/or glass for the preparation of substrate pieces. Other substrate
materials may be used as agreed by the parties concerned.
For each test specimen, two substrate supports of the same material are required with a cross-section
of dimensions as defined ISO 8339 (see Figures 1 and 2). Test substrates of other dimensions may be
used. In this case, the dimensions of the sealant bead and the area of adhesion shall be the same as
those defined in ISO 8339.
Dimensions in millimetres
Key
1 mortar substrates
2 sealant
3 spacer
Figure 1 — Test specimen with mortar substrates
...