ISO 23945-1:2022

Test methods for sprayed concrete - Part 1: Flash setting accelerating admixtures - Setting time

This document specifies the test method, sampling, procedure and determination of cement paste containing a flash setting accelerating admixture for sprayed concrete. Related terms and definitions are also given. This document does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this document to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

Méthodes d’essai pour le béton projeté — Partie 1: Adjuvants activateurs — Temps de prise

General Information

• Status: Published
• Publication Date: 10-Jul-2022
• ICS: 91.100.30 - Concrete and concrete products
• Technical Committee: ISO/TC 71/SC 1 - Test methods for concrete
• Drafting Committee: ISO/TC 71/SC 1/WG 7 - Test methods for sprayed concrete
• Current Stage: 6060 - International Standard published
• Start Date: 11-Jul-2022
• Due Date: 11-Mar-2022
• Completion Date: 11-Jul-2022

Overview

ISO 23945-1:2022 defines a standardized test method for evaluating the setting time of cement paste containing flash setting accelerating admixtures used in sprayed concrete (shotcrete). The standard specifies sampling, apparatus, environmental conditions, specimen preparation and the procedure-using Vicat apparatus-to determine initial and final setting times for both powdery and liquid accelerating admixtures. It also provides related terms and normative flow charts for paste preparation.

Key topics and technical requirements

• Scope and purpose
  • Tests the effect of a particular cement + flash setting accelerating admixture combination on setting time.
  • Intended for sprayed concrete / shotcrete applications; includes regional test conditions for tropical/subtropical climates.
• Test environment
  • Standard: (20 ± 2) °C and relative humidity > 50 %.
  • Alternative for tropical/subtropical: (27 ± 2) °C and 65 ± 5 % RH.
• Apparatus & specimen
  • Vicat apparatus and Vicat mould (top Ø 65 ±0.5 mm, bottom Ø 75 ±0.5 mm, depth 40 ±0.2 mm).
  • Flat trowel, mixer, glass graduates, balances (accuracy ±1 g / ±0.5 g), 50 ml syringe for liquid admixtures.
• Materials
  • Portland cement conforming to ISO 22965 series with specified fineness, C3A and alkali ranges and ≥ 42.5 28‑day strength.
  • Distilled/deionized water recommended for validation.
• Preparation & procedure
  • Typical test batch: 400 g cement with 140 g water (including water in liquid admixtures).
  • Powdery admixture: dry pre-mix 10 s, add water and mix 5 s (low) + 15 s (high).
  • Liquid admixture: pre-mix cement + water 30 s (low), add liquid admixture and mix 5 s (low) + 15 s (high).
  • Moulding within 50 s after final admixture addition; measure setting time immediately with frequent checks near initial set.
• Safety and applicability
  • The standard does not replace site safety practices; users must ensure regulatory and health compliance. Laboratory results may not exactly replicate field shotcreting conditions.

Applications and who uses it

• Admixture manufacturers: product validation and technical data sheets for flash setting accelerating admixtures.
• Shotcrete and sprayed concrete contractors: selecting and qualifying admixtures for tunnelling, mining, repairs, and rapid stabilization.
• Materials testing laboratories: routine quality control and conformity testing of cement–admixture combinations.
• Specifiers and engineers: assessing suitability of admixtures for fast-setting applications and establishing mix controls.

Related standards

• ISO 679 (cement strength test methods)
• ISO 9597 (setting time and soundness)
• ISO 22904 / ISO 22965 (additions / concrete)
• ISO 29581‑1 / ‑2 (cement chemical analysis)
• EN 196‑2, EN 196‑6; ASTM C187

Keywords: ISO 23945-1, sprayed concrete, flash setting accelerating admixture, setting time, shotcrete testing, Vicat, cement paste.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 23945-1
First edition
2022-07
Test methods for sprayed concrete —
Part 1:
Flash setting accelerating admixtures
— Setting time
Méthodes d’essai pour le béton projeté —
Partie 1: Adjuvants activateurs — Temps de prise
Reference number
© ISO 2022
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
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or ISO’s member body in the country of the requester.
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Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Significance and use .2
5 Test environment conditions . .2
6 Apparatus . 2
7 Materials . 3
7.1 Cement . 3
7.2 Water . 3
8 Procedures . 4
8.1 Preparation of cement paste . 4
8.1.1 Powdery flash setting accelerating admixture . 4
8.1.2 Liquid flash setting accelerating admixture . 4
8.2 Moulding test specimen . 4
8.3 Time of initial setting determination . 4
8.4 Time of final setting determination . 4
9 Provision and bias . 5
10 Test report . 5
Annex A (normative) Schematic diagram of cement paste preparation with powdery flash
setting accelerating admixture .6
Annex B (normative) Schematic diagram of cement paste preparation with liquid flash
setting accelerating admixture .7
Bibliography . 8
iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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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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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 1, Test methods for concrete.
A list of all parts in the ISO 23945 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
Introduction
Sprayed concrete is widely used for the stabilization of structures in a very short time and for concrete
applications without using moulds. In addition to being ideal for ground support in tunnelling and
mining, sprayed concrete is also used in repairs, restoration, new construction and many other fields.
The requirements for properties, test methods, standards and specifications for the spray-forming
process of concrete are different from those of cast-forming concrete. This document is intended to
provide a normative test method for determining the effect on the setting time of cement paste by flash
setting accelerating admixtures for sprayed concrete.
This document is applied under various climatic and geographical conditions, various levels of
protection and under different established regional traditions and experiences. Consequently, this
document includes conditions for tests covering standard test conditions and tropical and subtropical
regional environments.
This document is intended for use with other parts of the ISO 23945 series, which are intended to be
developed and which will provide requirements associated with the level of quality specified and the
methods to be employed for the execution of sprayed concrete.
v
INTERNATIONAL STANDARD ISO 23945-1:2022(E)
Test methods for sprayed concrete —
Part 1:
Flash setting accelerating admixtures — Setting time
1 Scope
This document specifies the test method, sampling, procedure and determination of cement paste
containing a flash setting accelerating admixture for sprayed concrete. Related terms and definitions
are also given.
This document does not purport to address all of the safety concerns, if any, associated with its use. It is
the responsibility of the user of this document to establish appropriate safety and health practices and
determine the applicability of regulatory limitations prior to use.
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 679, Cement — Test methods — Determination of strength
ISO 9597, Cement — Test methods — Determination of setting time and soundness
ISO 22904, Additions for concrete
ISO 22965 (all parts), — Concrete
ISO 29581-1, Cement — Test methods — Part 1: Analysis by wet chemistry
ISO 29581-2, Cement — Test methods — Part 2: Chemical analysis by X-ray fluorescence
EN 196-2, Method of testing cement — Part 2: Chemical analysis of cement
EN 196-6, Methods of testing cement — Part 6: Determination of fineness
ASTM C187 -16: 2016, Standard Test Method for Amount of Water Required for Normal Consistency of
Hydraulic Cement Paste
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
flash setting accelerating admixture
admixture to develop very early setting and very early hardening of sprayed concrete
Note 1 to entry: For more information on admixture, see ISO 19596.
ISO 23945
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