ISO 23945-1:2022

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
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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
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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.
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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.
3.2
powdery flash setting accelerating admixture
flash setting accelerating admixture (3.1) used in the form of powder
Note 1 to entry: This is usually fit for the dry spraying process operation.
3.3
liquid flash setting accelerating admixture
flash setting accelerating admixture (3.1) used in the form of liquid
Note 1 to entry: This is usually fit for the wet spraying process operation.
Note 2 to entry: Liquid admixture includes solution type and suspension type.
4 Significance and use
4.1 The performance of a flash setting accelerating admixture for sprayed mortar or concrete varies
with the composition of the cement as well as with environmental conditions. Even for a given cement
and specified testing conditions, the variation in specimen preparation, test procedure, operation time
and test equipment can result in a very different result of the setting time. In this way the test method
for the setting time of cement paste containing flash setting accelerating admixtures is quite different
from that of ordinary cement paste.
4.2 Since this test method involves the determination of the setting time of a particular combination
of a cement and a flash setting accelerating admixture, it therefore provides information on the
suitability for use of that particular combination.
4.3 The method described in this document can also be used for the determination of the setting time
of the cement paste with additions and flash setting accelerating admixtures for shotcrete.
4.4 The setting time of the combination established in the laboratory does not necessarily indicate
that the setting time will produce the same result in an actual shotcreting or at different temperatures
from laboratory temperatures.
5 Test environment conditions
The specimen preparation and setting time measurement should be conducted in a closed environment,
in which the temperature is maintained in the range of (20 ± 2) °C with relative humidity > 50 %.
For countries in tropical and subtropical climates, alternative environment conditions, with the
temperature maintained in the range of (27 ± 2) °C with humidity in the range of (65 ± 5) % can be
employed.
All the materials and apparatus should be kept at the same temperature required for the test.
6 Apparatus
6.1 Flat trowel, having a sharpened straight-edged steel blade 100 mm to 150 mm in length. The
edges when placed on a plane surface shall not depart from straightness by more than 1 mm.
6.2 Mixer, bowl, paddle and scraper, conforming to the requirements in ISO 679.
6.3 Glass graduates, 200 ml or 250 ml capacity, capable of dispensing to an accuracy of ±1 ml.
6.4 Mass-determining devices: balance for cement, c
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