ISO 18650-2:2025
(Main)Building construction machinery and equipment — Concrete mixers — Part 2: Procedure for examination of mixing efficiency
Building construction machinery and equipment — Concrete mixers — Part 2: Procedure for examination of mixing efficiency
This document specifies the procedure and requirements for examination of the mixing efficiency of batch-type and continuous-type concrete mixers as defined in ISO 18650-1. It is applicable to concrete mixers having a rated capacity greater than or equal to 0,5 m3.
Machines et matériels pour la construction des bâtiments — Malaxeurs de béton — Partie 2: Mode opératoire pour la détermination de l'efficacité de malaxage
l'ISO 18650-2:2014 spécifie le mode opératoire à suivre et les exigences à respecter pour la détermination de l'efficacité de malaxage des malaxeurs de type production discontinue et de type production en continu, tels que définis dans l'ISO 18650-1. Elle est applicable aux malaxeurs à béton de capacité nominale supérieure ou égale à 70/50.
General Information
Relations
Standards Content (Sample)
International
Standard
ISO 18650-2
Third edition
Building construction machinery
2025-03
and equipment — Concrete
mixers —
Part 2:
Procedure for examination of
mixing efficiency
Machines et matériels pour la construction des bâtiments —
Malaxeurs de béton —
Partie 2: Mode opératoire pour la détermination de l'efficacité de
malaxage
Reference number
© ISO 2025
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Requirements for mixer verified . . 1
5 Mixing performance test . 2
5.1 General .2
5.2 Concrete mix preparation.3
5.3 Sampling .3
5.3.1 General .3
5.3.2 Batch-type compulsory mixers .4
5.3.3 Gravity mixers .6
5.3.4 Continuous mixers .7
5.3.5 Sampling from a concrete mix hopper .8
5.4 Variance tests .9
5.4.1 Variance of air, mortar and coarse aggregate content in concrete mix .9
5.4.2 Consistency test . 12
5.4.3 Compressive strength test . 12
6 Evaluation of test results .13
7 Test report .13
8 Final remarks . 17
8.1 Filling ratio of tested mixer .17
8.2 Optimization of mixing time .17
Bibliography . 19
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,
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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
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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
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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 195, Building construction machinery and
equipment, Subcommittee SC 1, Machinery and equipment for concrete work.
This third edition cancels and replaces the second edition (ISO 18650-2:2014), which has been technically
revised.
The main changes are as follows:
— changed the Scope to be applicable to concrete mixers having a rated capacity greater than or equal to 0,5 m ;
— modified the drawing for number of specimens in Figure 1;
— modified Figure 2 and key;
— modified Figure 3 b) and key;
— modified the number of specimens in 5.4.1.1;
— modified the drawing of mixer in Figure 7 and corrected water temperature to (20 ± 2) °C
— modified Table 4;
— corrected keys marks for T to T in Figure 8.
1 3
A list of all parts in the ISO 18650 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
This document deals with the testing of the mixing capabilities of concrete mixers, characterized as the
recommended mixing time.
The test consists of the determination of the variance of the mortar, coarse aggregate and air content, and
the consistency of concrete mix samples, drawn after an assumed mixing time.
Compressive strength is also tested.
The measure of a concrete mixer’s efficiency is the value of the variance of the above parameters, after the
assumed mixing time.
This document provides for the preparation of concrete mix, sampling, execution of particular tests, criteria
of test result evaluation and the test report.
v
International Standard ISO 18650-2:2025(en)
Building construction machinery and equipment — Concrete
mixers —
Part 2:
Procedure for examination of mixing efficiency
1 Scope
This document specifies the procedure and requirements for examination of the mixing efficiency of batch-
type and continuous-type concrete mixers as defined in ISO 18650-1. It is applicable to concrete mixers
having a rated capacity greater than or equal to 0,5 m .
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 1920-3, Testing of concrete — Part 3: Making and curing test specimens
ISO 1920-4, Testing of concrete — Part 4: Strength of hardened concrete
ISO 3310-1, Test sieves — Technical requirements and testing — Part 1: Test sieves of metal wire cloth
ISO 11375, Building construction machinery and equipment — Terms and definitions
ISO 18650-1, Building construction machinery and equipment — Concrete mixers — Part 1: Commercial
specifications
ISO 20290-1, Aggregates for concrete — Test methods for mechanical and physical properties — Part 1:
Determination of bulk density, particle density, particle mass-per-volume and water absorption
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 18650-1 and ISO 11375 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/
4 Requirements for mixer verified
The design and execution of the whole structure of the mixer and its components, such as the mixing
chamber (drum, pan or trough), rotor with blades or paddle agitator(s), their directions of rotation, charging
and discharging devices (if any), should be verified according to the manufacturer’s instructions.
It shall be determined that the number of revolutions per minute of a drum or mixing tools conforms to the
manufacturer’s specification.
The drive system should be able to restart 5 min after being stopped when the mixer has completed the
mixing of the test batch as specified in 5.2.
NOTE 1 The “restart” is for the additional mixing and does not warrant a series of restarts for the next batches.
The mixer shall be discharged according to its design or as specified by the manufacturer. The closure of
the mixing chamber shall be so designed that the loss of the mix before discharge, i.e. during charging and
mixing, remains below 0,5 %.
NOTE 2 The “below 0,5 %” requirement does not apply to the 1st batch which has more adhesion of mortar to the
inner wall of drum.
5 Mixing performance test
5.1 General
The mixing efficiency is determined by the uniformity of the concrete mix and the compressive strength
of the concrete cubes or cylinders, sampled after mixing time. The determination of the uniformity of the
concrete mix includes the following variance tests on the sampled specimens:
a) air content;
b) content of mortar per unit volume;
c) content of coarse aggregate per unit volume;
d) consistency (slump).
The values of the concrete-mix component content (air, mortar, coarse aggregate), determined as the test
results, as well as the consistency and compressive strength, are subsequently used for calculation of their
variances.
For calculating the variance, ΔX, of the considered components’ content and other features, expressed as a
percentage, Formula (1) is applied:
XX−
ΔX = ×100 (1)
XX+
where
X is the value of component content, slump and compressive strength received from portion 1 or 2 —
larger value of X and X ;
1 2
X is the value of component content, slump and compressive strength received from portion 1 or 2 —
smaller value of X and X .
1 2
To explain the physical sense of Formula (1), it can be transformed to Formula (2):
X
...
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