NZS 3104:2003

Incorporating Amendment No. 1 and No. 2

New Zealand Standard

Specification for Concrete

Production
Superseding NZS 3104:1991
NZS 3104:2003
 NZS 3104:2003

COMMITTEE REPRESENTATION

Committee P 3104 was responsible for the preparation of this Standard and

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consisted of the following nominating organizations:

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Co-opted Chair
Cement & Concrete Association of New Zealand

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Building Research Association of New Zealand (BRANZ)
New Zealand Concrete Society

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New Zealand Ready Mixed Concrete Association
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© COPYRIGHT

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The copyright of this document is the property of the Standards Council. No
part of it may be reproduced by photocopying or by any other means without
the prior written permission of the Chief Executive of Standards New Zealand
unless the circumstances are covered by Part III of the Copyright Act 1994.

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Standards New Zealand will vigorously defend the copyright in this Standard.
Every person who breaches Standards New Zealand’s copyright may be liable

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to a fine not exceeding $50,000 or to imprisonment for a term not to exceed
three months. If there has been a flagrant breach of copyright, Standards
New Zealand may also seek additional damages from the infringing party, in
addition to obtaining injunctive relief and an account of profits.
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Published by Standards New Zealand, the trading arm of the
Standards Council, Private Bag 2439, Wellington 6140.
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Telephone: (04) 498 5990, Fax: (04) 498 5994.

Website: www.standards.co.nz
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AMENDMENTS
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No. Date of issue Description Entered by,

and date

1 June 2007 Minor adjustments and corrections, Incorporated in

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and a new clause (12.13.3.2 (b)) this edition.

added for on-site concrete production
plants.

2 February 2010 Recognises that there is now more than Incorporated in

one type of mechanism used for weigh this edition.
systems (knife edge/lever arm and load
cell). Clause 2.7.3 has been updated and
errors in the Contents, 1.3, 2.9.1, and
3.1.4 have been corrected.

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NOTES

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 NZS 3104:2003

CONTENTS PAGE

Copyright.....................................................................................IFC

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Referenced documents.................................................................. 4
Foreword........................................................................................ 5

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Section

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1 GENERAL................................................................................ 7

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1.1 Scope and interpretation................................................. 7
1.1.1 Scope................................................................. 7
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1.1.2 Interpretation...................................................... 7

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1.2 Definitions....................................................................... 7
Feb '10

2 PROVISIONS FOR READY-MIXED AND

SITE-MIXED CONCRETE...................................................... 10

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2.1 General......................................................................... 10
2.1.1 Concrete.......................................................... 10
2.1.2 Limitations on specified strengths range.......... 10

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2.2 Inspection facilities........................................................ 10
2.3 Supervision and technical control................................. 10
2.3.1 Technical control.............................................. 10
2.3.2 Supervision...................................................... 10
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2.3.3 Monitoring of test results...................................11
2.4 Materials.........................................................................11
2.4.1 General.............................................................11
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2.4.2 Alkali aggregate reaction..................................11

2.4.3 Coarse aggregate............................................ 12
2.4.4 Sand................................................................. 12
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2.4.5 Other provisions............................................... 13

2.5 Batching plant............................................................... 13
2.5.1 Storage of materials......................................... 13
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2.5.2 Weighing hoppers............................................ 14

2.5.3 Admixtures....................................................... 14
2.6 Measurement of materials............................................. 14
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2.6.1 Cement and aggregates.................................. 14

2.6.2 Water............................................................... 14
2.6.3 Admixtures....................................................... 14
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2.6.4 Accuracy.......................................................... 14
2.7 Weighing equipment..................................................... 15
2.7.1 General............................................................ 15
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2.7.2 Cement and aggregates.................................. 15

2.7.3 Testing and accuracy of weighing
equipment........................................................ 16
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2.8 Concrete mixing............................................................ 18

2.8.1 Mixing by stationary mixer............................... 18
2.8.2 Mixing by truck mixer....................................... 18
2.9 Transportation............................................................... 19
2.9.1 Ready-Mixed Concrete.................................... 19
2.9.2 Delivery by truck mixer or agitator................... 19
2.9.3 Addition of water on site................................... 19
2.9.4 Delivery of concrete by non-agitating
equipment........................................................ 19 ➤

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 NZS 3104:2003

2.10 Responsibility for mix design......................................... 20

2.10.1 Normal Concrete (N)........................................ 20
2.10.2 Special Concrete (S)........................................ 20

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2.10.3 Compliance ..................................................... 21
2.11 Mixing records............................................................... 21

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2.11.1 Ready-Mixed Concrete.................................... 21

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2.11.2 Site-Mixed Concrete........................................ 21
2.11.3 Availability of records....................................... 21

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2.12 Concrete mixes – general requirements....................... 21
2.13 Target mean strengths and variability control................ 21
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2.13.1 Normal Concrete.............................................. 21

2.13.2 Special Concrete.............................................. 24

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2.13.3 Compliance and evidence of a
variability control.............................................. 25
2.14 Concrete mix design..................................................... 26

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2.14.1 Mix design information..................................... 26
2.14.2 Confirmatory tests............................................ 26
2.15 Control tests and their evaluation.................................. 26
2.15.1 Slump tests...................................................... 26


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2.15.2 Yield tests........................................................ 27
2.15.3 Air content tests............................................... 28
2.15.4 Performance test for mixers and
truck mixers...................................................... 28
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2.15.5 Strength tests for proof of control..................... 29
2.15.6 Evaluation of strength test results.................... 30
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2.15.7 Plant test records............................................. 31

2.15.8 Testing of laboratory equipment....................... 32
2.16 Quality audit.................................................................. 33
2.16.1 Certificate of Audit............................................ 33
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2.16.2 Information for Certificate of Audit.................... 33

2.16.3 First audit......................................................... 33
2.16.4 Quarterly monitoring........................................ 33
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2.16.5 Control............................................................. 33

3 PROVISIONS FOR PRESCRIBED MIX CONCRETE........... 34

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3.1 General......................................................................... 34
3.1.1 Production........................................................ 34
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3.1.2 Compliance...................................................... 34
3.1.3 Strengths of Prescribed Mix Concrete............. 34
3.1.4 Definition.......................................................... 34
3.2 Supervision and technical control................................. 34
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3.2.1 Batching........................................................... 34
3.2.2 Certification...................................................... 34
3.2.3 Disputes........................................................... 34
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3.3 Materials........................................................................ 34
3.3.1 General............................................................ 34
3.3.2 Aggregate........................................................ 35
3.3.3 Proportion of sand and aggregate................... 36
3.3.4 Weight batching............................................... 36

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 NZS 3104:2003

3.4 Prescribed concrete mixes............................................ 36

3.4.1 Proportions of materials................................... 36
3.4.2 Methods of volume batching............................ 36

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3.4.3 Accuracy.......................................................... 36
3.5 Concrete mixing............................................................ 37

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3.5.1 Loading............................................................ 37

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3.5.2 Remaining water.............................................. 37

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4 CONCRETE MIXERS............................................................ 38
4.1 General......................................................................... 38
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4.1.1 Performance.................................................... 38
4.1.2 Operation......................................................... 38

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4.1.3 Application....................................................... 38
4.2 Performance.................................................................. 38
4.2.1 Mixing............................................................... 38

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4.2.2 Non-complying mixers..................................... 38
4.2.3 Mixer maintenance and repair......................... 38
4.2.4 Identification plates.......................................... 39
4.3 Batch mixers................................................................. 39


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4.3.1 Mixer controls................................................... 39
4.3.2 Rated mixing capacity...................................... 39
4.3.3 Minimum mixing criteria................................... 39
4.3.4 Determination of minimum mixing time or
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number of revolutions...................................... 39
4.3.5 Identification plates.......................................... 39
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4.4 Continuous mixers........................................................ 40

4.4.1 Charging rate................................................... 40
4.4.2 Identification plates.......................................... 40
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Figure
2.1 Evaluation of coefficient of variation . ................................ 24
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4.1 Identification plate for mixers............................................. 40

Table
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2.1 Grading recommendations for combined and .

uncombined coarse aggregates......................................... 12
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2.2 Accuracy of measurement ................................................ 15

2.3 Scale division .................................................................... 16
2.4 Accuracy of weighing equipment and frequency of tests .. 17
2.5A Criteria for plants with a minimum testing regime
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of 10 tests per month ........................................................ 22

2.5B Criteria for plants with a minimum testing regime
of 6 tests per month .......................................................... 22
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2.5C Plant criteria for interim Certificate of Audit ....................... 23

2.6 Maximum tolerances for slump at the plant ...................... 27
2.7 Performance test requirements of uniformity of
concrete for stationary and truck mixers............................ 29
2.8A Evaluation of compression test results............................... 32
2.8B Evaluation of compression test results............................... 32
3.1 Prescribed mixes (P).......................................................... 35
3.2 Combined grading requirements........................................ 36
3.3 Accuracy of measurement.................................................. 37

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 NZS 3104:2003

REFERENCED DOCUMENTS

Reference is made in this document to the following:

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NEW ZEALAND STANDARDS

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NZS 3109:1997 Concrete construction

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NZS 3111:1986 Methods of test for water and aggregate for concrete

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NZS 3112:1986 Methods of test for concrete
Part 1: Tests relating to fresh concrete
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Part 2: Tests relating to the determination of

strength of concrete

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NZS 3121:1986 Specification for water and aggregate for concrete

NZS 3122:1995 Specification for Portland and blended cements

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(General and special purpose)

NZS 3123:1974 Specification for Portland pozzolan cement

(type PP cement)

NZS 3125:1991
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Specification for Portland-limestone filler cement

NZS 3604:1999 Timber framed buildings

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NZS 4210:2001 Masonry construction: Materials and workmanship

NZS 4229:1999 Concrete masonry buildings not requiring specific

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engineering design

AUSTRALIAN STANDARDS
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AS 1012.1-1993 Methods of testing concrete – Sampling of fresh

concrete
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AS 1012.20-1992 Methods of testing concrete – Determination of

Amd 1 chloride and sulfate in hardened concrete and
June '07 concrete aggregates
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AS 1478.1-2000 Chemical admixtures for concrete, mortar and

grout – Admixtures for concrete
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AMERICAN STANDARD
ASTM C1152/C1152M-97 – Standard Test Method for Acid-Soluble
Chloride in Mortar and Concrete
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OTHER DOCUMENT
TR3 – Alkali Aggregate Reaction – Minimizing the Risk of Damage to
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Concrete (Guideline notes and Model Specification Clauses).

LATEST REVISIONS
The users of this Standard should ensure that their copies of the.
above mentioned New Zealand Standards and referenced overseas
Standards are the latest revisions or include the latest amendments.
Amendments to New Zealand and Joint Australian/New Zealand
Standards can be found on www.standards.co.nz.

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 NZS 3104:2003

FOREWORD

This Standard supersedes the 1991 version, which was amended

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from the original 1983 Standard.

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The principal changes incorporated into this revision are:

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1. All concrete production is brought into one Standard. The provisions

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of NZS 3108 have been revised and form section 3 of this Standard.
NZS 3108 is superseded and withdrawn.
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2. The previous system of “grading” plants has been withdrawn,

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primarily because the batching/production systems are now all
of a similar accuracy. This has been replaced with an auditing
process.

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3. The word “grade” is now used in the international sense as
designating strength.

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4. Consequential changes arising from NZS 3109 are included (e.g.
Normal, Special and Prescribed classes of concrete).

5. The statistical control and monitoring of concrete strength remain

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substantially the same but the auditing process for plants, claiming
compliance with this Standard, has been expanded.
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6. The manufacturing Standard for Concrete Mixers NZS 3105 is

withdrawn and replaced by section 4 of this Standard.
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Compliance with the provisions of this Standard ensures compliance

with the requirements for the supply of fresh concrete given in
NZS 3109.
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REVIEW OF STANDARDS
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Suggestions for improvement of this Standard will be welcomed.

They should be sent to the Chief Executive, Standards New Zealand,
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Private Bag 2439, Wellington 6020.

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NZS 3104:2003

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 NZS 3104:2003

NEW ZEALAND STANDARD

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SPECIFICATION FOR CONCRETE PRODUCTION

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1 GENERAL

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1.1 Scope and interpretation
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1.1.1 Scope

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1.1.1.1
This Standard prescribes minimum requirements for the production of fresh concrete.

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1.1.1.2
Section 1 of this Standard contains general clauses.
Section 2 provisions shall be complied with for the production of concrete at batching plants away from
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the construction site, on the construction site and in a precast concrete works.
Section 3 sets out provisions for using prescribed concrete mixes.
Section 4 sets out requirements for concrete mixers.
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1.1.2 Interpretation
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1.1.2.1
In this Standard, the word “shall” indicates a requirement that is to be adopted in order to comply with
the Standard. The word “should” indicates a recommended practice.
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1.1.2.2
The full titles of referenced documents cited in this Standard are given in the list of Referenced Documents
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immediately preceding the Foreword.

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Feb '10
1.2 Definitions
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For the purposes of this Standard the following definitions shall apply:

ADMIXTURE. A material other than Portland cement, aggregate, or water added to concrete to modify
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its properties.

AGITATOR. A drum mounted integrally with a truck, which when fully or partially loaded with a concrete
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mixture, is capable by its rotation of maintaining the concrete in a uniform mass and of discharging it
with the required degree of uniformity.
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AUDITING ENGINEER. The auditing person(s), independent of the supplier, who is qualified and
experienced in the production and quality control of concrete production in accordance with this Standard.
The Auditing Engineer is appointed by the supplier to audit the quality assurance of the supplier’s
plant(s) in accordance with the Standard. The Certificates of Audit issued must be signed by a Chartered
Professional Engineer or Corporate Member of the Institution of Professional Engineers New Zealand.
NOTE – The concrete plant auditing scheme run by the New Zealand Ready Mixed Concrete Association,
which itself is independently audited, is able to issue Certificates of Audit as required by this Standard.

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 NZS 3104:2003

BATCHING PLANT. A plant capable of weighing, in the required quantities and to the required degree
of accuracy, the materials constituting a batch of concrete. A batching plant may also have a concrete
mixer mounted integrally within it.

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CERTIFICATE OF AUDIT. A document produced by the Auditing Engineer(s) to indicate that the plant

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complies with the requirements of this Standard at the time of the audit. The document can be issued

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as an Annual Certificate of Audit valid for a maximum period of 12 months from the date of issue or as
an Interim Certificate of Audit, which is valid for three months.

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CONCRETE MIXER. A rotating drum, tube, trough or pan fitted with fins or paddles which is capable
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of combining all the ingredients of a concrete batch into a uniform mass in not more than 70 revolutions
at mixing speed and of discharging the concrete with the required uniformity.

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DESIGNER. The professional engineer (or architect), his/her deputy, or authorized representative,
nominated on behalf of the owner to monitor the works to which concrete is being supplied.

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GRADE. A group of mixes produced with a common specified strength (e.g. 20 grade).

INDEPENDENT EQUIPMENT TESTING. The periodic testing of batching weigh scales by the supplier
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or other specialist, being independent of the plant’s owners or operators.

NOMINAL MAXIMUM AGGREGATE SIZE. The sieve size, in the sieve series listed in table 1 of NZS 3121.
Pertains to the coarsest sieve on which more than 15 % of the total coarse aggregate is retained.
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NORMAL CONCRETE. All concrete specified by 28-day strength within the range 17.5 to 50 MPa and
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produced in accordance with the provisions of section 2 and/or sections 3 and 4 of this Standard.

PLANT ENGINEER. The engineer experienced in quality control of concrete production, and in mix
design, nominated by the concrete producer to assume responsibility for mix designs and for the quality
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of production. He or she shall be either a Chartered Professional Engineer, or a person whose name
is included on the register of the Engineering Associates' Registration Board.
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PLANT SUPERVISOR. The person suitably experienced in the manufacture and quality control of
concrete to exercise supervision of all aspects of concrete production and delivery.
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PRESCRIBED MIX CONCRETE. Concrete specified by 28-day strength within the range 10 to 25 MPa,
and produced in accordance to the provisions of section 3 of this Standard
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PURCHASER. The person or organization placing concrete orders, and to whom the producer would
normally look for payment or its authorization (usually the construction contractor).
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READY-MIXED CONCRETE. Concrete made from a mixture of Portland cement, coarse aggregates,
sand, and water with or without admixtures. It is batched at a batching plant and mixed in a concrete
mixer incorporated in the plant or in truck mixers held stationary at the plant until mixing is completed.
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The Ready-Mixed Concrete is then delivered to the site in a suitably plastic state for placing.

SAMPLE, REPRESENTATIVE. A sample of batch concrete taken as prescribed in 3.4.3 of NZS 3112:
Part 1.

SAMPLE, SNATCH. A sample taken as prescribed in 3.4.2 of NZS 3112: Part 1.

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 NZS 3104:2003

SAMPLING, RANDOM. Sampling by a procedure in which all of the concrete from the selection is to be
made has an equal chance of being sampled, (e.g. sampled without bias, such as by the use of tables
of random numbers or by other well established methods).

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SAMPLING, SELECTED. Sampling after the concrete has been sighted (e.g. on the basis of some

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visible feature prompting a check test) or the premeditated sampling of a particular batch prompted by

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the desire to have further information about that particular batch.

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SATELLITE PLANT. A plant not permanently staffed but operated by personnel from a plant having a
current Certificate of Audit of compliance to this Standard, using the same materials and mix designs
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as the main plant.

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SLUMP, DELIVERY. The nominal slump value within specified tolerances that Ready-Mixed Concrete
is required by the Purchaser to have at the time of its arrival and for up to 30 minutes after, subject to
the requirements of 2.9.

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SLUMP, PLANT. Slump measured at the plant when the mixing process is complete

SLUMP, TARGET. The slump desired by the producer at the time of mixing.
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SPECIAL CONCRETE. Concrete where the Purchaser has specified requirements which differ from
those of normal concrete.
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SPECIFIED COMPRESSIVE STRENGTH OF CONCRETE. A singular value of strength, normally at
age 28 days unless stated otherwise, denoted by the symbol f'c, which classifies a concrete as to its
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strength class for purposes of design and construction. That level of compressive strength is required
to be equalled or exceeded by 95 % of the concrete produced.

STRENGTH. Compressive strength at 28 days as tested in accordance with NZS 3112.

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SUPPLEMENTARY CEMENTITIOUS MATERIALS (SCMs). Materials such as fly ash, blast furnace
slag and silica fume.
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SUPPLIER. The operator of the plant supplying concrete.

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TARGET AIR CONTENT. The air content which the concrete mix has been designed to achieve.
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TARGET MEAN STRENGTH. The mean strength which the concrete mix has been designed to achieve
as determined by 2.13.

TARGET YIELD. The volume of concrete which the mix design is calculated to produce.
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TECHNICIAN. A person trained to take samples of materials and concrete, to prepare test specimens
and to test them, all in accordance with the relevant NZ Standards.
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TRUCK MIXER. A concrete mixer mounted integrally with a truck, and also capable of operating as an
agitator for delivering a batch of mixed concrete and discharging at a construction site.

YIELD. Defined in NZS 3112: Part 1 – Tests relating to fresh concrete.

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 NZS 3104:2003

2 PROVISIONS FOR READY-MIXED AND SITE-MIXED CONCRETE

2.1 General

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2.1.1 Concrete

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Ready-Mixed Concrete and site-mixed concrete production shall conform to the relevant requirements

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set out in either section 2 or section 3 (respectively) of this Standard. A plant claiming compliance with.
section 2 shall display a current quality Certificate of Audit issued by an Auditing Engineer.

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2.1.2 Limitations on specified strengths range
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Concretes described as Normal in NZS 3109 shall be supplied to the strength range 17.5 MPa to 50
MPa to the provisions of this section. Concrete described as Special in NZS 3109 shall be supplied

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to the provisions of this section together with such additional specifications as required by NZS 3109.

C2.1.2

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Concrete with strengths over 50 MPa is defined in NZS 3109 as Special Concrete. Where Normal
Concretes are specified to have performance criteria other or in addition to strength, they will be
defined as Special.

2.2 Inspection facilities sN

Reasonable access shall be provided for the Designer and/or Auditing Engineer to inspect all materials,
Admixtures, processes and concrete test records relating to the mix being supplied, and to obtain samples
without charge to determine whether the concrete is being made in accordance with this Standard or
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other relevant specifications. The testing of such samples shall be at the Purchaser’s cost unless prior
agreement has been arranged with the producer. All tests and inspections shall be conducted so as not
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to interfere unnecessarily with the manufacture and delivery of the concrete.

2.3 Supervision and technical control

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2.3.1 Technical control

The Plant Engineer shall be experienced in mix design and quality control. After he/she has evaluated
the coarse aggregate and sand, he/she shall design the concrete mixes and prescribe and monitor the
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manufacturing, quality control, and testing procedures. He/she shall provide mix design as required
by 2.14 showing (together with other mix design data) the anticipated water/cement ratio for any mix
at the designed slump.
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The Plant Engineer shall either be based at or maintain close contact with the plant at all times, and
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visit the plant as frequently as may be necessary to effectively discharge these responsibilities, but no
less than one visit every six months.

C2.3.1
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It is recommended that the plant be visited four times a year during the initial year of production or
when materials, plant or staff are changed.
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2.3.2 Supervision

2.3.2.1
The Plant Supervisor, who shall be suitably experienced in the manufacture and quality control of
concrete, shall exercise supervision of all aspects of plant operations and concrete production.

2.3.2.2
A person trained in concrete testing shall be available at the plant to carry out the appropriate frequency
sampling and testing of concrete and aggregate to the provisions of NZS 3112 and NZS 3111.

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 NZS 3104:2003

C2.3.2.2
Testing of hardened concrete samples from a plant may be tested at a laboratory or other plant
equipped for such testing remotely from the original plant, subject to appropriate transport provisions

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for specimens.

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Concrete Technicians are deemed to be trained if they have satisfied the requirements of New
Zealand Qualifications Authority (NZQA) Unit Standard 12019 Carry Out Routine Tests on Concrete.

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2.3.3 Monitoring of test results
The results of all routine tests as defined in 2.15 shall be transmitted regularly to both the Plant Engineer
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and Plant Supervisor no less frequently than monthly. The results are to be monitored by the Plant

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Supervisor and shall be continuously evaluated by the Plant Engineer to ensure compliance with tables
2.8A and 2.8B. Summaries of other control tests shall be reported to the Plant Engineer at intervals
of not more than one month, except that any non-complying test results shall be reported immediately
(see also 2.15.6).

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The Plant Engineer shall communicate with the plant as frequently as is necessary to both request and
to follow up on any action, which has been deemed necessary by the monitoring. The Plant Engineer
shall communicate to the plant in writing no less frequently than every three months.

2.4 Materials
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2.4.1 General
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The materials used shall comply with the following specifications:
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(a) Portland Cement

NZS 3122 Specification for Portland and blended cements;
NZS 3123 Specification for Portland pozzolan cement;
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NZS 3125 Specification for Portland limestone filler cement.

(b) Water, coarse aggregates and sand

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NZS 3121 Specification for water and aggregate

Except as provided in 2.4.2, 2.4.3 and 2.4.4 of this Standard
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TR3 Alkali Aggregate Reaction – Minimizing the Risk of Damage to Concrete (Guideline notes and
Model Specification Clauses).
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(c) Admixtures
AS 1478 Chemical Admixtures for Concrete
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NOTE – Testing shall generally be to the relevant part of AS 1012, except where this differs substantially from
the corresponding test to NZS 3112. Where the AS 1012 test regime is altered, the test method used shall
be stated in the test report.
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2.4.2 Alkali aggregate reaction

Where the sand or aggregate are potentially reactive as defined in TR3:

For Normal Concrete, the concrete producer shall certify that the total alkali content in the concrete will
not exceed 2.5 kg/m3 from all sources. If not the concrete shall be designated as Special Concrete.

11
 NZS 3104:2003

2.4.3 Coarse aggregate

2.4.3.1

*
Where concrete contains a coarse aggregate of nominal maximum size 19 mm or greater, but not
exceeding 37.5 mm, the coarse aggregate shall be stored and batched in at least two size ranges. For

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concrete containing a coarse aggregate of nominal maximum size greater than 37.5 mm, the coarse
aggregate shall be stored and batched in at least three size ranges.

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C2.4.3.1

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Table 2.1 gives some grading recommendations for combining coarse aggregates and requirements
for non-combined coarse aggregates.
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it but not more than 10% of the documents subscribed to may be held in printed form at any one time.

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Table 2.1 – Grading recommendations for combined and uncombined coarse aggregates

Nominal Percentages passing test sieves with square openings

size range of the following sizes

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(mm) (mm)

53.0 37.5 26.5 19.0 16.0 13.2 9.5 4.75 0.30

37.5 to 4.75 100 85 – 100 35 – 70 0 – 25 0 – 5 0–1
26.5 to 4.75 100
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85 – 100 0 – 35 0 – 5 0–1
19.0 to 4.75 100 85 – 100 0 – 40 0 – 5 0–1
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16.0 to 4.75* 100 85 – 100 0 – 60 0 – 10 0–1
13.2 to 4.75* 100 85 – 100 0 – 70 0 – 10 0–1
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9.5 to 4.75* 100 85 – 100 0 – 10 0–1

* Non-combined single range coarse aggregate grading

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2.4.3.2 Compliance tests for coarse aggregate grading

For each coarse aggregate size range used, a sample shall be obtained and tested for compliance with
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the acceptance criteria NZS 3121.

The results shall be recorded for each 100 m3 of aggregate delivered, but tests need not be more
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frequent than once per day and shall not be less frequent than once per week.

2.4.3.3 Confirmation tests for coarse aggregate grading

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Whenever not fewer than 18 of the last 20 consecutive tests show compliance with NZS 3121, the
frequency of testing may be reduced to one test for each 300 m3 of aggregate delivered, but it shall be
not less often than once per fortnight.
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2.4.4 Sand
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2.4.4.1 Compliance tests for sand uniformity

For each sand component used, a sample shall be obtained and tested for uniformity compliance as
defined in NZS 3121, and the results recorded for each 50 m3 of sand delivered. Tests need not be
more frequent than once per day and shall not be less frequent than once per week.

2.4.4.2 Confirmation tests for sand uniformity

When not fewer than 45 of the last 50 consecutive tests show compliance with the uniformity requirements
of NZS 3121, the frequency of testing may be reduced to one test for each 150 m3 of sand delivered.
However, testing need not be more frequent than once per day, and shall not be less frequent than
once per fortnight.

12
 NZS 3104:2003

2.4.5 Other provisions

2.4.5.1 Aggregate supply to more than one plant

*
If a concrete producer has plants sharing the same aggregate supply, the frequency of testing shall
apply at one of the plants and a lesser or nil frequency may apply at the other plants, at the discretion

d
of the Plant Engineers.

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2.4.5.2 Aggregate producer tests

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When an aggregate producer elects to provide testing of materials being supplied to the plant as required
under 2.4.3.2 and 2.4.4.1, then no further testing shall be required by the concrete producer. The
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it but not more than 10% of the documents subscribed to may be held in printed form at any one time.

copies of the results of the aggregate producers’ tests shall be held for a minimum of three years by the.
concrete producer for inspection.

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2.4.5.3 Cleanness of aggregates
For each coarse aggregate size range used, samples shall be obtained at the request of the Plant

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Engineer and tested for cleanness for compliance with the requirements of NZS 3121.

A sample of sand used shall be obtained at the request of the Plant Engineer, and tested for sand
equivalent for compliance with NZS 3121. Where more than one sand is used per batch, a combination
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of the sands in their nominal proportions may be tested.

If the aggregate producer makes changes to the source of coarse aggregates or sands, the test frequency
required of the aggregate producer shall be one per week for the first month after the change.
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C2.4.5.3
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NZS 3121 permits a sand equivalent test value (SE) as low as 60. For economical mix design, cleaner
and hence higher values of SE should be sought. It should be noted that the SE test is primarily
suitable for natural sands by evaluating clay and silt content. Manufactured sands recording low
SE values may be able to be demonstrated to be satisfactory for concrete production by a series of
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concrete property tests conducted by the aggregate supplier.

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2.4.5.4 Test data

If requested, the aggregate supplier shall provide test data to confirm the acid soluble chloride content
Amd 1
of aggregate and sand supplied to the producer using test procedures according to ASTM C1152 or.
AS 1012.20, or X-ray spectrometry (XRF) by a suitably experienced IANZ-accredited chemical laboratory.
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June '07

2.4.5.5 Aggregate over 37.5 mm nominal size

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This material is outside the scope of Normal Mixes and requires specification provisions under the terms
of a Special Mix.
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2.4.5.6 Recycled water

The use of recycled water, or recycled slurry as all or part of the mix water, shall be permitted provided
the provisions of NZS 3121 are followed.
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2.5 Batching plant

2.5.1 Storage of materials

2.5.1.1 Cement
Cement shall be stored and handled to provide protection against deterioration or contamination and to
be capable of being inspected at all times. Means shall be employed whereby cement which has been
held longest at the plant is the first to be used.

13
 NZS 3104:2003

2.5.1.2 Aggregates
All aggregates held at or in the vicinity of the plant shall be stored and handled in such manner that
they will not segregate or be contaminated by any other materials. Stockpiles shall be free draining.

*
Provision shall be made for the separate storage and batching of each sand and each nominal size range

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of coarse aggregate in a manner which will prevent intermingling. Control of the aggregate feed to the

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weighing hopper shall be such that it will ensure compliance with the tolerances of accuracy set out in.
table 2.2.

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2.5.1.3 Admixtures
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All admixtures held at or in the vicinity of the plant shall be stored, handled and protected against
deterioration or contamination. Any admixture exceeding the storage life recommended by the manufacturer,

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shall be removed from the plant. All admixture stock or storage containers shall be clearly labelled.

2.5.1.4 Bagged product

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Product in bags shall be kept in dry storage and expiry dates shall be strictly adhered to.

C2.5.1.4
Paper bags can be water soluble and thus it is essential to keep the product dry.

2.5.2 Weighing hoppers

sN
Weighing hoppers for cement and aggregates shall be constructed or equipped to discharge efficiently,
so that not more than 0.25 % of batch masses of aggregates, and not more than 5 kg of cement shall
rd
be left in the hopper. For the cement hopper there shall be provision for increasing the tare in the next
weighing to make allowance for the residual amount. The aggregate and cement weigh hoppers shall
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be so adjusted that there is an even flow of all materials throughout the discharge.

2.5.3 Admixtures
Dispensing and associated transfer pipe work shall be such as to prevent the premixing of admixtures
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prior to the discharge into the mixer or batching water tank.

2.6 Measurement of materials

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2.6.1 Cement and aggregates

The cement and aggregates shall be measured by weighing.
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2.6.2 Water
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Water shall be measured either by volume or by weighing.

2.6.3 Admixtures
Admixtures shall be measured by sight glass or pulse meter.
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2.6.4 Accuracy
Materials shall be measured in the quantities prescribed in the mix design, within the tolerances shown
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in table 2.2.

14
 NZS 3104:2003

Table 2.2 – Accuracy of measurement

Materials Maximum tolerances permitted from the target masses

*
or volumes

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Cement (1) ±1 %

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(by mass)

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Water (2) ± 2.5 %
(by mass or volume)
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Aggregates (1) ±2 % for any fraction provided that the total mass of aggregate

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(by mass) is within 1 %

Admixture (3) ±10 % of the amount specified

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(by mass or volume)

NOTE –
(1) For cement and aggregates, the maximum permitted tolerances shall be as in this table or the maximum

(2)
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scale division permitted in table 2.3, whichever is the greater.

For water, the target batch mass/volume may not be fully dispensed, the held back water only being
used if necessary for workability adjustments.
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(3) The admixture dispenser accuracy shall be checked at the standard admixture dosage levels for a 1 m3
load. For admixtures, where the manufacturer recommends greater accuracy, such recommendations
shall be complied with.
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2.7 Weighing equipment

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2.7.1 General
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2.7.1.1
The displayed mass shall be readily discernible to the operator.

2.7.1.2
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Where the displayed mass is indicated on a scale, the scales shall be graduated in divisions not greater
than those given in table 2.3.
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2.7.2 Cement and aggregates

Cement shall be weighed in a hopper and preferably on scales separate from those used for other
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materials.

If a combined scale is used, the cement shall be weighed first and the scale accuracy shall be that
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required for cement scales in tables 2.2 and 2.3.

15
 NZS 3104:2003

Table 2.3 – Scale division

Mixer size Maximum scale divisions

*
(kg)

d
Cement scales Aggregate scales

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Mixers less than 2 m3 capacity 5 10

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Mixers of 2 m3 capacity and over 10 20
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2.7.3 Testing and accuracy of weighing equipment

2.7.3.1 Facilities
Amd 2 Test weights or weigh testing equipment shall always be available for promptly checking the accuracy of

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Feb '10 all weighing equipment. Test weights and weigh testing equipment shall be certified as to their calibration.

2.7.3.2 Extent of tests

(a) Routine scale tests.
sN
(i) For weigh systems directly dependent on knife edge/lever arm mechanisms including lever arm/
load cell combinations, the readings shall be taken at not less than 10 points evenly distributed
throughout the full working range. An error calculation shall be carried out for each scale check
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and shall comply with the requirements of table 2.4
(ii) For weigh systems directly dependent on load cell mechanisms, the readings shall include
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points at, or near, 10 %, 50 %, and 90 % of the full working range. An error calculation shall be
carried out for each scale check and shall comply with the requirements of table 2.4;
(b) Independent scale checks shall follow the provisions of (a) above and shall comply with the
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Amd 2
Feb '10 requirements of table 2.4.
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2.7.3.3 Frequency and type of test

Routine scale tests shall be conducted not less frequently than stated in table 2.4 by the Plant Supervisor.
Independent scale tests shall be conducted not less frequently than stated in table 2.4 by a representative
of an organization recognized as a scale system specialist. Failure to maintain the test frequency is a
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compliance breach of this Standard.

rig
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16
 NZS 3104:2003

Table 2.4 Accuracy of weighing equipment and frequency of tests

Maximum interval between Maximum variation (1)
tests

*
Routine testing by plant supervisor

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Cement scales – lever arm Once per month (2) 0.4 % of working range

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Cement scales – load cell Once per 3 months (3) 0.4 % of working range

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Aggregate scales – lever arm Once per 3 months (2) 0.4 % of working range
Once per 6 months (3)
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Aggregate scales – load cell 0.4 % of working range

it but not more than 10% of the documents subscribed to may be held in printed form at any one time.

Water measuring device

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Scales Once per 6 months 2.0 %
Meter Once per 6 months 2.0 %
Independent testing by equipment manufacturer/supplier (4)

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Cement scales As required but not less than . 0.2 % of working range
once per 2 years
Aggregate scales sN
As required but not less than
once per 2 years
0.2 % of working range

Admixture dosing pulse meters

Annually 10.0 % of amount specified
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Admixture dosing
Sight glass Once on installation 2.0 %
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Water measuring device

(excluding trim water)
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Scales As required but not less than 2.0 %

once per 2 years
Meter
As required but not less than 2.0 %
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once per 2 years

NOTE –
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(1) Maximum variation relates to the summation of errors at each stage of a weigh check.

(2) Test frequencies for plants complying with 2.7.3.2(a)(i).

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(3) Test frequencies for plants complying with 2.7.3.2(a)(ii).

Amd 2
Feb '10 (4) The term ‘equipment manufacturer’ shall be taken to include a scale system specialist.
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2.7.3.4 Accuracy of equipment

At the time of routine or independent testing, the equipment shall comply with the accuracy requirements
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of table 2.4. Where error calculations show that the measuring equipment is outside the requirements of
table 2.4, the Plant Supervisor shall take immediate steps to correct the error and retest the components.

2.7.3.5 Recording of test weighing measurements

A permanent record of all test-weighing measurements shall be kept at the plant.

If independent testing proves that the equipment complies with the requirements of this specification,
the equipment manufacturer’s representative shall provide a certificate to that effect, which shall include
reference to table 2.4 of this Standard and be available for inspection at the plant.

17
 NZS 3104:2003

2.8 Concrete mixing

2.8.1 Mixing by stationary mixer

*
2.8.1.1

d
The mixing time shall be measured from the time when all materials are in the mixer and the time at

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which discharge from the mixer occurs. Such mixing time shall comply with manufacturer's requirements
for the plant and produce concrete that complies with the uniformity requirements of 2.15.4.

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C2.8.1.1
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it but not more than 10% of the documents subscribed to may be held in printed form at any one time.

Typical times for free fall drum mixers are 1.5 minutes for mixers with a capacity of 1 m3 or less; for
larger mixers this time should be increased by 20 sec for each additional 0.5 m3 capacity. Modern

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high intensity mixers can have mixing times as low as 60 seconds.

2.8.1.2

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The interior of the mixer shall be examined daily and any build up of hardened concrete which may
reduce the efficiency of the mixer shall be removed before the mixer is used again.

2.8.2 Mixing by truck mixer

2.8.2.1
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Water shall be measured, added to the mix, and the mixing operation completed at the batching plant.
After all materials as batched are in the truck mixer, the drum shall turn a minimum of 70 revolutions
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at mixing speed. If further solid material or water is added the drum shall complete at least a further
30 revolutions at mixing speed before leaving the plant. Water shall not be added to the bowl after the
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truck mixer has left the batching plant except as permitted for Ready-Mixed Concrete in 2.9.3.

2.8.2.2
The number of revolutions of the drum, as specified in 2.8.2.1, may be reduced to such a figure as
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is shown to be necessary by the mixer performance test prescribed in 2.15.4 to achieve the required
degree of uniformity of the concrete.
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2.8.2.3
The rotational speed of the truck-mixing bowl shall be such as to ensure that the requirements of the
mixer performance test shall be met. The minimum speed shall not be less than the manufacturer’s
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recommendation for optimum mixing speed, and in any case not less than 10 RPM.
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2.8.2.4
If the size of the batch is at least 1 cubic metre less than the rated capacity, the number of revolutions
at mixing speed may be reduced, but to no fewer than 50, provided the requirement of the mixer
performance test are met.
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2.8.2.5
After completion of mixing, all revolutions of the drum shall be at agitating speed as referenced in 2.9.2.1.
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2.8.2.6
The interior of the mixer shall be examined daily and any accretion of hardened concrete which may
reduce the efficiency of the mixer shall be removed before the mixer is used again.

18
 NZS 3104:2003

2.9 Transportation

2.9.1 Ready-mixed concrete

*
Amd 2
Except as may be provided in 2.9.4, delivery shall be made in a truck mixer or an agitator of the revolving
Feb '10
drum type, either of which shall be capable of maintaining the mix in a homogeneous state complying

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with 2.15.4 and 2.9.2.

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2.9.2 Delivery by truck mixer or agitator

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2.9.2.1
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The speed of revolution of the drum during agitation while in transit to the site shall be neither less than
2 RPM nor more than 6 RPM.

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2.9.2.2
Full discharge of concrete from agitators and truck mixers shall be completed within 90 minutes or such

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other period as may be designated by the Plant Engineer after the introduction of the cement to the
aggregates or of the mixing water to the cement and aggregates.

NOTE – The use of some admixtures (e.g. set retarding) and additives (e.g. flyash materials) and ambient
sN
temperature conditions will influence the time permitted.

2.9.3 Addition of water on site

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2.9.3.1
Where the slump of the concrete as delivered is less than specified and the concrete is less than 1
hour old, a limited addition of water by the concrete supplier shall be permitted subject to the following:
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(a) Special concrete has not been specified;

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(b) The amount of water added shall be limited to increase the slump to the nominated value and shall
under no circumstances exceed 10 litres per cubic metre of concrete;
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(c) After the water addition the mixer bowl shall be turned at a minimum of 30 revolutions at mixer speed;

(d) The slump shall be re-measured and the amount of added water recorded on the concrete delivery
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docket.

2.9.3.2
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For concrete that is to be supplied by a Ready-Mixed Concrete producer, no addition to the concrete
shall be made on the construction site by the Purchaser, without the prior agreement of the producer.
If any addition is made without such approval, the Purchaser shall assume responsibility for the mix.
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2.9.4 Delivery of concrete by non-agitating equipment

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2.9.4.1
Subject to agreement by the Purchaser and Plant Engineer, concrete may be transported in suitable
non-agitating equipment if the mix is designed for this purpose.

2.9.4.2
The bodies of non-agitating equipment shall be smooth and watertight.

19
 NZS 3104:2003

2.9.4.3
Covers for protection against weather conditions (either wetting or drying) shall be provided when required.

*
2.9.4.4
Where discharge from non-agitating equipment may not be completed without risk of undue delay, either

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in transit or on site, this type of transport shall not be used.

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2.10 Responsibility for mix design

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2.10.1 Normal Concrete (N)
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it but not more than 10% of the documents subscribed to may be held in printed form at any one time.

The concrete producer shall assume responsibility for mix designs for all Normal Concrete of specified
compressive strength (N) 17.5 MPa to 50 MPa and their properties as follows:

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(a) The proportions and amounts of coarse aggregate and sand;

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(b) The water/cement ratio and cement content to meet the appropriate performance requirements set
out in 2.13.1;

(c) The suitability, quantity and performance of any admixture used;

(d) The workability of the concrete;

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(e) Yield of the concrete.
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NOTE – This also applies to grouts supplied to the requirements of NZS 4210.
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2.10.2 Special Concrete (S)

For all mixes over 50 MPa or mixes where concrete properties other than characteristic strength form
the basis of a specification, the mix shall be designated Special Concrete(s).
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C2.10.2
If a mix from the Normal Concrete range is specified with a special requirement as specified in
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NZS 3109, then it becomes a Special Concrete.

2.10.2.1
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For all Special Concrete mixes the Purchaser or Designer shall specify the properties required, together
with specified testing and compliance tolerances. The concrete producer shall assume responsibility
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for mix designs to meet the specified requirements. Any grounds for the possible non-compliance are
to be stated by the producer.

C2.10.2.1
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The specifier/Purchaser is required to specify the special parameters required for the concrete and to
give a method by which the producer can demonstrate compliance. A CCANZ publication ‘Specifying
Concrete for Performance’ gives guidance to the selection of concretes used in special conditions.
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It may be appropriate to use compressive strength testing at alternative times rather than the normal
28 day period.

It will be necessary for the specifier to have discussions with the producer as to initial acceptance of
test results and the ongoing method of quality assurance.

20
 NZS 3104:2003

2.10.3 Compliance
If requested, the Plant Engineer to the plant shall advise the Designer or Auditing Engineer of the source,
type, and size of aggregates, type and brand of cement, target strength, water/cement ratio, and the

*
type and quantity of admixture (if any) being used, together with confirmatory evidence that the concrete
being produced complies with all the requirements.

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2.11 Mixing records

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2.11.1 Ready-Mixed Concrete
At a Ready-Mixed Concrete plant records shall be kept which identify for each batch the following:
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(a) Specified strength and size of batch;

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(b) Delivery slump ordered, target slump, and the actual slump when measured;

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(c) Details of mix proportions, either directly or by code number and the name and quantity of admixture,
if any;

(d) Amount of added water;

(e) Length of mixing time.

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2.11.2 Site-Mixed Concrete
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A record of Site-Mixed Concrete shall be kept which shall show:
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(a) Specified strength, size of batches, and number of batches;

(b) Designed proportions, target slump, amount of added water and admixture dosage;
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(c) Length of mixing;

(d) Destination of the concrete in the works.

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2.11.3 Availability of records

The records shall be available for inspection on request by the Purchaser.
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2.12 Concrete mixes – general requirements

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All concrete shall be proportioned to produce concrete at the nominated or delivery slump, as the case
may be (within the tolerances permitted in table 2.6) and the concrete shall be able to be compacted to
a dense state by high frequency vibration or by such other method as has been specified.
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2.13 Target mean strengths and variability control

2.13.1 Normal Concrete

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2.13.1.1
The criteria for the design of Normal Concrete mixes, 17.5 MPa to 50 MPa strengths at 28 days, shall
be based on random representative samples with not more than 5 % of results falling below f' c .

C2.13.1.1 The design strength is based upon f'm = f'c + 1.64 Sd where Sd is the standard deviation
for the particular mix and f'm is the target mean strength.
➤

21
 NZS 3104:2003

The use of the above formula provides for a 1 in 20 probability that the concrete strength will be
below the specified value.

*
The generic equation is f'c + k Sd . Both Sd and k are factors that are influenced by test results and
the frequency of testing.

d
The coefficient of variation (COV) is determined from the equation below wherein 30 results have

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been used to develop Sd and mean strength.

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2.13.1.2
Tables 2.5A and 2.5B set out the criteria for compliance with 2.13.1.1 for Normal Concrete based upon
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historical and statistical data in accordance with 2.13.3.

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Table 2.5A – Criteria for plants with a minimum testing regime of
10 tests per month (f'c + 1.64 Sd )

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Specified strength f'c MPa

Grade MPa 17.5 20 25 30 35 40 45 50

Maximum COV % 12.5 11.5 11 sN10.5 10 9.5 9.0 8.5

Target mean strength MPa 22 24.5 30.5 36 42 47.5 53 58

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Table 2.5B – Criteria for plants with a testing regime of
6 tests per month (f'c + 2.25 Sd )
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Specified strength f'c MPa

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Grade MPa 17.5 20 25 30 35 40 45 50

Maximum COV % 12 11.5 11 10 9.5 9.0 8.5 8.0

St

Target mean strength MPa 24 27 33 38.5 44.5 50 56 61

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C2.13.1.2
rig

Historical data has provided a series of Sd values which for the purposes of providing a monitoring
mechanism have been used to create the maximum coefficients of variation used in table 2.5A and
table 2.5B. The calculation to establish the coefficient of variation is based on a minimum of 30 results.
Sd
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COV = x 100
Mean strength

For plants using the six tests per month criteria there is a requirement to ensure a full set of 30 results
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is achieved for one strength grade. The balance of testing should be distributed between all other
mixes produced by the plant in the year.
For plants having a special testing regime of more than 20 tests per month, an alternative statistical
system may be agreed on between the producer/Purchaser/Auditing Engineers for Special Concrete
supply to a project.
Where there are no historical records of the use or experience of local materials, it is recommended that
an Sd of 6 MPa be adopted for the initial mix design and the mixes modified as records demonstrate
lower variability.

22
 NZS 3104:2003

2.13.1.2.1
Satellite plants can only be linked with a parent plant complying with the requirements of table 2.5A or
table 2.5B.

*
2.13.1.3 Compliance requirements

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If the mean strengths of table 2.5A or table 2.5B and/or coefficients of variation are not met, the following

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actions shall be implemented:

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(a) Strength below target mean COV within 1 % of value, the target strength of the mix/es shall be raised.
An interim Certificate of Audit will be issued for a three-month period after which time test results are
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to be submitted to the Auditing Engineer for re-assessment;

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(b) Strength above target mean of table 2.5C and COV above the limits of table 2.5A or table 2.5B but
below the values of table 2.5C, the cause of the variation shall be determined. An interim Certificate
of Audit will be issued for a three-month period after which time test results are to be submitted to

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the Auditing Engineer for re-assessment;

(c) Strength below mean and COV greater than 1 % limit above the values of table 2.5A or table 2.5B,
the target strength of the mix/es shall be raised. The Certificate of Audit shall be withdrawn until such
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time as subsequent resubmitted test data, is deemed to comply. The plant shall operate to the test
frequency provisions of one test per day of operation and subsequent testing frequency of one test
for each 75 cubic metres of daily production.
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NOTE – The size of sets above 30 results and numbers of sets available for review will influence the decision
in respect of actions taken in an overall audit of capacity for the plant.
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If test frequencies for sampling and testing or calibration checks for equipment are not carried out in
accordance with the appropriate clauses of this Standard or nominated Standards, then an Certificate
of Audit shall be withdrawn or withheld.
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Where a plant is submitting a first series of 30 results as under 2.13.3.2, the COV shall meet the
requirements of figure 2.1.
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C2.13.1.3
Variability and monitoring matters are specified later in this Standard.
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If the re-assessment referred to in (b) establishes that reducing the variation cannot be achieved,
then the audit certificate requiring compliance with table 2.5C could be extended for a further period
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Amd 1
June '07 of 9 months.

Table 2.5C – Plant criteria for interim Certificate of Audit

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Specified strength MPa

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Grade 17.5 20 25 30 35 40 45 50

Maximum coefficient of variation % 16 15.5 14.5 13.5 12.5 11.5 11 10.5

Target mean strength MPa 24 26.5 32.5 38.5 44 49 55 60

23
 NZS 3104:2003

*
n d
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it but not more than 10% of the documents subscribed to may be held in printed form at any one time.

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Amd 1
June '07

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Amd 1
June '07
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Figure 2.1 – Evaluation of coefficient of variation

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2.13.2 Special Concrete

2.13.2.1 Strengths over 50 MPa

The target mean strength shall be calculated in accordance with 2.13.1.1 unless otherwise varied by
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the Designer. The Plant Engineer having due regard to the local materials being used to manufacture
the concrete shall select Sd .
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C2.13.2.1
Significant other issues begin to influence the ability of Special Concrete to reach higher strengths
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such as aggregate strength and shape. The Plant Engineer may need to discuss the Sd factor with
the Designer because a skew statistical distribution factor may arise. Historical data indicates that
typical Sd values for high strength concrete range from 5 – 8 MPa.
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2.13.2.2 Characteristics other than strength

The Designer shall specify the special parameters required together with specified testing and compliance
tolerances as required in NZS 3109. The Plant Engineer shall take account of these requirements
when designing the Special Concrete and shall establish with the Designer an initial test assurance of
compliance followed by an assurance test programme during the supply of the concrete.

C2.13.2.2
The specifier is required to specify the special parameter required for the concrete and to give a
method by which a producer is required to demonstrate compliance.

24
 NZS 3104:2003

It may be appropriate to use strength testing at alternative times rather than the normal 28-day period.

It will be necessary to develop a sampling and testing compliance regime for Special Concretes.

*
2.13.3 Compliance and evidence of a variability control

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2.13.3.1

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Evidence is required to establish that an effective control of variability is in place as set out in 2.13.3.2,

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and the suitability of the mix designs as set out in 2.13.3.3.
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2.13.3.2 No performance records of plant

A plant initially producing concrete, which seeks to demonstrate compliance with this Standard and

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with NZS 3109, shall comply with section 3 of this Standard or shall undertake prior testing as set out
in (a) and (b).

To establish compliance with this Standard:

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(a) A plant shall establish the ratio of materials and cement to be used at the plant by carrying out a
series of tests as described in 2.13.3.3, and shall generate a series of not fewer than 30 results in
one mix. The relationship of materials, cement, and strength as described in 2.13.3.3, together with
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the analysis of the 30 results for compliance with figure 2.1, shall be carried out by the Plant Engineer
and submitted to an Auditing Engineer or Designer; and

(b) To establish compliance with the interim audit status in this Standard, a plant shall establish a
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relationship between materials and cement to be used at the plant by carrying out a series of tests
to generate a series of not fewer than 10 results in each mix required for audit status. An analysis
for compliance with the 28-day target strengths of table 2.5C or the 28-day f'c strengths of table
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2.5A when compression tested at 7 days, together with compliance with the COV values of table
2.5C, shall be carried out by the Auditing Engineer or Designer. If compliance with either condition
is met and an independent weigh scale check of the plant has been satisfactorily completed, then a
an

Amd 1
June '07 3-month interim audit certificate can be issued.

2.13.3.3 Mix design performance

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A group of concrete mixes shall be designed using aggregates and cement to be used at the plant..
The mixes shall either be designed on the basis of cement contents of 200, 250, 300, 350, 400 and.
450 kg/m3, or on the basis of actual strength design mixes for 17.5, 20, 30, 40, 45 and 50 MPa. All the
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mixes shall be designed for a 100 mm slump and use 19 mm maximum aggregate size.

A minimum of two mixes at each cement content or strength shall be sampled and tested for compressive
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strength at 28 days. The strength results shall be plotted against cement content to produce group strength
relationship curve with MPa strength on the vertical axis and cement content in kg on the horizontal axis.
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The following shall also be considered:

(a) Where it is considered that an admixture will be consistently used in concrete production, this may
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be included in the curve. Where an admixture may only be used over a range of concrete within
the group, the concrete mix at the limit of the range of admixture use shall be tested both with and
without the admixture and the results plotted;
(b) The group relationship shall be revalidated every three years unless it can be demonstrated to the
Auditing Engineer that the production compressive strength results cover the group range and indicate
that the relationship has not changed;

(c) The group relationship of materials and cement shall be permitted to be adopted for use on other
plants that are using the same materials.

25
 NZS 3104:2003

2.13.3.4 Plants with performance records

The ability of the plant to produce concrete with compliant strength and variability characteristics of
tables 2.5A and 2.5B and 2.13.1.3 shall be measured by analyzing the test results averaged over all

*
mixes tested.

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2.14 Concrete mix design

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2.14.1 Mix design information
The total water required for each concrete mix design at the desired target slump shall be determined

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by the Plant Engineer. Information showing the batch masses, additives dosage, target yield, target
strength and target slump of each mix design together with other appropriate mix design details shall be
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available. This information shall be kept at the plant for a minimum of three years and shall be available

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for inspection by the Designer or Auditing Engineer. The information shall make due allowance for the
effect of water in the aggregates on both the added water and the aggregate masses.

2.14.2 Confirmatory tests

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2.14.2.1
At the start of production at the plant, checks on the total water content shall be carried out and during
production at the discretion of the Plant Engineer and/or Plant Supervisor on random batches.

2.14.2.2
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Where total water content tests are carried out, the following information shall be documented at the plant:
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(a) Date and time;

(b) Batch weights of cement and aggregates;

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(c) Amount of added water;

(d) Slump;
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(e) Air content (entrained and/or entrapped);

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(f) Name and quantity of admixtures, if any;

(g) Yield;
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(h) Moisture content of each size of aggregates;

(i) Total amount of water;

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(j) Water/cement ratio by weight;

(k) Compression test.

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Where any of the above tests have the method of test specified in NZS 3111 or NZS 3112, such a
method shall be employed.
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2.15 Control tests and their evaluation

2.15.1 Slump tests

2.15.1.1
Practicable measures shall be taken to ensure that the specified delivery slump of the concrete is within
the tolerances required by table 9.1 of NZS 3109, subject to the provisions of 2.9.1 for Ready-Mixed
Concrete. A slump test shall always be taken when a compression test is made. Slump tests shall be
carried out in accordance with NZS 3112: Part 1.

26
 NZS 3104:2003

2.15.1.2
No more than 20 % of 30 consecutive tests taken to determine the initial mixing slump shall fall outside
the limits set out in table 2.6.

*
Table 2.6 – Maximum tolerances for slump at the plant

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Tolerance

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Target slump Representative sample Snatch sample

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(mm) (mm) (mm)
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60 or less ±20 ±20

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70 – 110 ±20 ±30
Amd 1
June '07 120 and above ±30 ±40

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NOTE – Target slump is the slump selected by the producer to take into account the distance and temperature
conditions for delivery. In the case of site production it is likely to be the same as the specified value.

2.15.1.3 Flowing concrete

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Where flowing concrete is specified for grouting masonry to the requirements of NZS 4210, the flowing
ability shall be measured in accordance with NZS 3112:Part 1. Alternative flowing concrete applications
are deemed Special Concretes and the method of test shall be specified by the Designer.
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2.15.1.4
Not more than 20 % out of 10 consecutive spread value results shall vary by more than ±15 % of the
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specified spread value.

2.15.2 Yield tests

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2.15.2.1 Purpose
The yield test, where the density of the freshly mixed and compacted concrete is measured, has two
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purposes:

(a) For the Purchaser, the volume of concrete yielded by the batch is calculated by comparing the
measured wet density of the concrete with the actual batch mass;
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(b) For the mix Designer, the measured density can be compared with the design density of the mix
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tested. This will give the earliest available indication of a change in water demand or air content that
may affect strength.

NOTE – The air content should be measured in all yield tests, including non air-entrained concrete, because
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there will always be some residual air. This is normally in the range of 1.0 % to 2.0 %. Loss of precision in the
evaluation of yield occurs if this air is not allowed for.
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2.15.2.2 General
Yield tests shall be carried out in accordance with NZS 3112: Part 1, except for calculating yield Y for
the purpose of 2.15.2.1(a), V shall equal the nominal cubic metre of concrete which was batched.

NOTE – Refer to NZS 3112 for definitions of V and Y.

2.15.2.3 Frequency
Yield tests on random batches covering a wide range of mixes produced shall be carried out not less
than once per week. At a ready-mixed satellite plant, a yield test shall be taken for each five days of
plant operation.

27
 NZS 3104:2003

2.15.2.4 Compliance
For compliance with 2.15.2.1(a), the control shall be such that the average yield of any six consecutive
yield tests shall not be less than 1.00 and no result shall fall below 0.98. Such results shall be available

*
to the Purchaser.

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2.15.2.5 Mix evaluation

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A minimum of three confirmatory yield tests shall be carried out on each new basic design when it is
first introduced for regular production. If the result of any yield test differs by more than ±1 % from the

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target yield established by the Plant Engineer in his mix design, the proportions of the mix concerned
shall be adjusted and a further yield test conducted until a result within the above tolerances is achieved.
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2.15.3 Air content tests

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2.15.3.1
Where air entraining admixtures are used, air entrainment tests shall be carried out at not less than

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once a day, except where nine out of 10 consecutive results of tests taken comply with the tolerances
set out in 2.15.3.3(b). In this case, the frequency of testing may then be reduced to once per week. At
a satellite plant one air test shall be taken for every five days of plant operation.

2.15.3.2 sN
The method of test shall comply with the requirements of NZS 3112: Part 1.

2.15.3.3
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For at least nine out of 10 consecutive results of the tests taken, the total entrained plus entrapped air
shall fall within the limits set out below:
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(a) The target air content for a mix shall be nominated;

(b) The measured air content shall be within ±1.5 % of the target air content.
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2.15.4 Performance test for mixers and truck mixers

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2.15.4.1
Evaluation tests shall be conducted on mixers and truck mixers at 12-monthly intervals, and after any
modification to the mixer or method of charging the mixer.
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2.15.4.2
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These tests shall be on snatch samples taken at the one-sixth and five-sixths point of a full batch as
discharged. Test results shall not differ by more than the amounts set out in table 2.7.

2.15.4.3
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Mixing times shall be those normally used for batching concrete at the plant.
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28
 NZS 3104:2003

Table 2.7 – Performance test requirements of uniformity of concrete

for stationary and truck mixers

*
Test Maximum permissible difference between
the results of two samples from a batch

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Weight per cubic metre 30 kg

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Slump 30 mm
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Air content 1 %

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Mean compressive strength at 28 days of 10 % of f'c or 3.0 MPa whichever is the greater
5* specimens taken from each sample

* Where the number of test specimens comprising tests for compressive strength is permitted by 2.15.5.2 to

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be reduced to two, the number of test specimens for the mixer test may also be reduced from five to two
provided the range between the two results does not exceed 2 MPa. If this occurs, the test must be repeated.

2.15.5 Strength tests for proof of control sN

2.15.5.1 Method of testing
Tests of compressive strength of concrete specimens at age 28 days shall be performed under the
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general supervision of the Plant Engineer or the plant Technician acting on the instructions of the Plant
Engineer. Such tests shall be made from random representative or random snatch samples taken at the
appropriate frequency set out in 2.15.5.3 in accordance with the following requirements of NZS 3112:
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Part 2, only by personnel who have had proper training in the techniques required:

(a) Moulding of test cylinders.................................................................................................. section 3;

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(b) Curing of test cylinders............................................................................................... 3.5.1 or 3.5.2;

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(c) Capping (where required).................................................................................................. section 4;

(d) Determination of compressive strength............................................................................. section 6;

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(e) Statistical analysis of strength test results....................................................................... section 10.

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C2.15.5.1
It should be noted that special precautions are required when sampling and testing concretes of
strengths more than 50 MPa.
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Refer to C2.3.2.2 for commentary on appropriate training.

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2.15.5.2 Number of test specimens

A set of test specimens shall consist of three specimens made from one sample of concrete, except when
the number of tests exceeds 20 and the 28-day compressive testing mean has a within-test coefficient
of variation of the test series of less than 4 %, as calculated by the method described in NZS 3112:.
Part 2, then the number of specimens per set may be reduced to two.

29
 NZS 3104:2003

2.15.5.3 Frequency of testing

2.15.5.3.1 Ready-Mixed Concrete

*
The minimum frequency of compressive strength testing at the Ready-Mixed Concrete plant shall be
not less than any of the following requirements:

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(a) An average of one test per 75 m3 of production up to 15,000 m3 per annum, with an additional test

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for every 250 m3 above 15,000 m3;

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(b) At least 10 tests per month except that in the case of plants producing less than 9000 m3 per annum
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6 tests per month are permitted, provided that the mixes are designed and evaluated on the basis
of table 2.5B and 2.15.6;

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(c) A satellite plant shall test at the rate of one test per 75 cubic metres of production.

NOTE – These test results may be combined with those from the parent plant for analysis purposes as de-

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scribed in 2.15.6.

2.15.5.3.2 Site-Mixed Concrete

Each day during the manufacture and placing of concrete, unless otherwise directed by the Designer,
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for each 75 m3 of concrete produced one sample shall be taken for the preparation of compression test
specimens for control testing of the concrete.

When early age or field cured tests are required they shall be considered additional to the above
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requirements except at the discretion of the Designer.

2.15.6 Evaluation of strength test results

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2.15.6.1 General
Concrete strength results shall be promptly scrutinized and monitored continuously by the Plant Engineer,
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Technician, or Plant Supervisor.

The monitoring procedures adopted by the Plant Engineer shall be fully documented and take into
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account the provisions of tables 2.8A and 2.8B.

Testing, recording and evaluation at monthly intervals shall be conducted on at least one mix representative
of production with a specified strength of not greater than 30 MPa, and also on one mix with a specified
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strength greater than 30 MPa where such a product is being manufactured.

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NOTE – It is recommended that producers, particularly those with a small annual production, should institute
a compression testing programme, which will place emphasis upon the most commonly produced mixes. This
will ensure that sufficient numbers of test results are forthcoming from those mixes to enable a statistically
valid coefficient of variation to be calculated.
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2.15.6.2 Monitoring of most recent results

The most recent six consecutive results shall be examined in terms of the appropriate cautionary limit
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values. If these values are not met, the Plant Engineer, Technician, or Plant Supervisor shall critically
review all aspects of production to ascertain the possible cause and take appropriate corrective action.

Alternatively, at the discretion of the Plant Engineer, the monitoring of the most recent results by means
other than the evaluation of groups of six results, but equally as effective, may be adopted so as to
ensure that appropriate corrective action is taken promptly when this becomes necessary.

NOTE – Appropriate corrective action could mean no action at all, particularly if evidence from other mixes
taken in much the same circumstances shows no falling off in quality. The reason for this is that the value
chosen for the mean of six results is such that there is a small chance of failure with a particular group of six
results in a series that is fully complying.

30
 NZS 3104:2003

2.15.6.3 Continued evaluation of test results

2.15.6.3.1

*
Tests on the mix, or mixes chosen for control purposes, shall be evaluated monthly for mean strength
and coefficient of variation. This series of tests is to be continuous for 12 months. After that time, as

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each month’s fresh results come to hand, they are to be included in the series and an equal number of

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early results is to be eliminated, achieving a continual updating.

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NOTE – The greater the number of test results in a series in a given time, the more confidence that there can
be in the information on variability. As described in 2.13.3.2, 30 is the least number that is generally accepted
as giving any reliable indication. It takes numbers well over 100 before there is any accurate appreciation of
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the true variability. This is why a continual updating of the 12 months’ series has been selected to give an
assessment of variability. As the new month’s tests are added, they would need to be markedly different to

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have a discernible effect on the mean strength. Tests should therefor be monitored on a day-to-day basis as
they come to hand. A procedure should be adopted that would, if necessary, sound a warning before the end
of the month, thereby avoiding the possibility of lowering of quality.

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2.15.6.3.2
The best estimated overall coefficient of variation of the series shall be calculated by the method given
in NZS 3112:Part 2. If the coefficient of variation is not more than 1 % greater than the appropriate

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value in tables 2.8A and 2.8B and the mean strength is equal or greater than the minimum target mean
strength shown in tables 2.8A and 2.8B, it shall be deemed the series is complying.

NOTE – The appropriate value for mean strength would in general be the target mean strength, but for a
single set of 30 results, the value could be the figure shown in item (c) of tables 2.8A and 2.8B. In this case,
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further evidence from earlier test results should be examined to ensure that the target mean strength is being
achieved for the continuing series of results.
It is envisaged that Plant Engineers will set concrete Target Mean Strengths a little above the minimum values
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given in tables 2.8A and 2.8B so as to give some protection against the unexpected.

2.15.6.3.3
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If the mean strength required by item (c) of tables 2.8A and 2.8B is not achieved, then reference to
2.13.1.3 shall be made and the consequential actions followed.
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C2.15.6.3.3
The principal course of action will be to increase the target strength of the concrete mix(es) in question
until such time as the cause of the variation can be identified and dealt with.
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2.15.6.3.4 Termination of a test series

A new test series may be started by the Plant Engineer, where there have been:
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(a) Significant changes in plant;

(b) Changes in the source of raw materials;

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(c) Changes in plant control, personnel, or methods;

(d) Significant changes in mix design.

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NOTE – Minor variations in cement content to compensate for variations in cement quality during the year,
or minor adjustments to mix designs to compensate for fluctuating sand or aggregate gradings, need not be
considered as significant changes warranting the starting of a new series.

2.15.7 Plant test records

A record of all control tests required by 2.15 to be taken at the plant, shall be kept by the producer and
shall be made available for inspection on request by the Purchaser or the Designer by arrangement.
The record shall clearly identify the batches of concrete from which tests are taken with the plant mixing
records required under 2.11.

31
 NZS 3104:2003

2.15.8 Testing of laboratory equipment

Test weights shall always be available for promptly checking the accuracy of all weighing equipment. Test
weights shall be certified as to their calibration.

*
Table 2.8A – Evaluation of compression test results

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Plants opting for not fewer than 10 tests per month

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Grade MPa 17.5 20 25 30 35 40 45 50
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Max COV % 12.5 11.5 11 10.5 10 9.5 9 8.5

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Min target mean strength mix MPa 22 24.5 30.5 36 42 47.5 53 58

Cautionary limit to be equalled or exceeded by the mean of any consecutive group of six results (b)

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20 22.5 28.5 33.5 39 44.5 49.5 55

Cautionary limit to be equalled or exceeded by the mean of any consecutive group of 30 results (c)

21 24.0
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29.5 35 40.5 46 51.5 56.5

Rejection limit (a) individual result

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Representative sample 15 17 21.5 26.5 31.5 36.5 41.5 46.5

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Amd 1
June '07
Snatch sample 14 16 20.5 25.5 30.5 35.5 40.5 45.5

Table 2.8B – Evaluation of compression test results

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Plants opting for not fewer than six tests per month
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Grade MPa 17.5 20 25 30 35 40 45 50

Max COV % 12 11.5 11 10 9.5 9 8.5 8

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Min target mean strength mix MPa 24 27 33 38.5 44.5 50 55.5 61

Cautionary limit to be equalled or exceeded by the mean of any consecutive group of six results (b)
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22 25 31 36 41.5 47 52.5 57.5

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Cautionary limit to be equalled or exceeded by the mean of any consecutive group of 30 results (c)

23 26 32 37.5 43 49 54 59.5
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Rejection limit (a) individual result

Representative sample 15 17 21.5 26.5 31.5 36.5 41.5 46.5

Amd 1
June '07
Snatch Sample 14 16 20.5 25.5 30.5 35.5 40.5 45.5

32
 NZS 3104:2003

2.16 Quality audit

2.16.1 Certificate of Audit

*
Compliance with this Standard requires an Certificate of Audit, issued by an Auditing Engineer. The
Certificate of Audit must be revalidated within a maximum period of 12 months.

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C2.16.1

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The object of the audit is to check that the requirements of this Standard are met in all respects. The

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plant report is designed to provide as much of the necessary information as possible, certified by the
Plant Engineer and the Plant Supervisor. Both the plant report and the on-site inspections facilitate
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the process. Whilst the Auditing Engineer could, in time, compile the reported information from the
original records during a plant inspection the opportunity to study the report prior to the inspection,

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provides focus to the inspection. In addition to the review of data, including the documentation of
monitoring by the Plant Engineer, the audit permits the review of the tests carried out (including
frequency of testing and the success of the quality assurance system) to be confirmed by the review

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of the year’s results.

2.16.2 Information for Certificate of Audit

Each application for audit shall be accompanied by a report by the Plant Engineer and Plant Supervisor,
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which summarizes the performance of the plant for a review period up to 12 months. The plant report
must be submitted to the Auditing Engineer within six weeks of the end of the review period and if justified,
the certificate will be issued within four months of the end of the review period and will be valid for up
to 12 months. (An interim certificate may be issued to permit the plant to rectify minor deficiencies.)
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After consideration of the plant report, the Auditing Engineer may request further information including
explanations, the monitoring records, details of tests not reported or reported in summary, and any other
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information relative to concrete production.

2.16.3 First audit

In the case of the first audit, an inspection of the plant will be made by the Auditing Engineer’s assessor
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(by appointment after receipt of the plant report). It will be necessary for the Plant Engineer, the Plant
Supervisor, the testing Technician, and the batcher to be present. All records shall be available for
examination. The assessor will require to see concrete being produced, and sampling and testing
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carried out. In the case of revalidation audits, physical site assessments will be made at intervals not
exceeding three years.
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2.16.4 Quarterly monitoring

Evidence of the monitoring process shall be submitted to the Auditing Engineer every three months,
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consisting of a summary of the number of tests carried out during the quarter.

2.16.5 Control
Control of materials, equipment, yield, slump, air content, and mixing efficiency are to be certified in
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the plant report.

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33
 NZS 3104:2003

3 PROVISIONS FOR PRESCRIBED MIX CONCRETE

3.1 General

*
3.1.1 Production

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Production of Prescribed Mix Concrete shall conform to the relevant requirements set out in this section.

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C3.1.1

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Prescribed Mix Concrete was formerly referred to as ordinary grade.
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it but not more than 10% of the documents subscribed to may be held in printed form at any one time.

3.1.2 Compliance
Compliance of concrete manufactured to this section shall be by confirmation that the mix proportions

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specified in table 3.1 have been met.

3.1.3 Strengths of Prescribed Mix Concrete

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Production of Prescribed Mix Concrete is limited to 10, 15, 17.5, 20, and 25 MPa nominal strengths at
28 days as prescribed in table 3.1.

C3.1.3
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Note that the basis of compliance for these nominal prescribed strength mixes is not by compressive
strength but as in table 3.1.

Concrete of 15 and 10 MPa shall not be used for reinforced concrete applications.
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Amd 2
3.1.4 Definition
This definition is additional to those in 1.2 and relates specifically to section 3.
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Feb '10

BUILDER'S MIX (all-in aggregate). A combined aggregate consisting of graded proportions of coarse
aggregate with a maximum size 20 mm through to graded proportions of sand.
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3.2 Supervision and technical control

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3.2.1 Batching
The supervision of the concrete production shall ensure that the prescribed quantities of materials are
batched in accordance with table 3.1.
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3.2.2 Certification
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On request from the Purchaser, the supervisor of concrete production shall certify that compliance with
the batching requirements of table 3.1 has been met.

3.2.3 Disputes
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In the event of a dispute, concrete shall either be wet sampled and the proportions determined, or
hardened concrete shall be submitted for chemical analysis to determine cement content.
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3.2.3.1 Rejection criteria

Where such testing demonstrates that the average cement content from two samples is more than 25
kg below the prescribed rates per cubic metre in table 3.1, the concrete shall be rejected.

3.3 Materials

3.3.1 General
All materials used shall comply with 2.4, except as provided for by 3.3.2.

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 NZS 3104:2003

Table 3.1 – Prescribed mixes (P)

Mix
Proportions (volume) Prescribed mixes – basic information

*
damp(1)
Amount per cubic metre Yield per

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cement
SSD(2) Damp(3) Wet(4) bag

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10 MPa dry mix Cement 1 200 kg 200 kg 200 kg 0.200 m3
50mm slump builder’s mix 9 2050 kg 2110 kg 2160 kg
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water 0.4 160 litres 100 litres 50 litres

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15 MPa Cement 1 240 kg 240 kg 240 kg 0.145 m3
130mm slump builder’s mix 6.75 1875 kg 1925 kg 1975 kg
water 0.8 200 litres 150 litres 100 litres

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17.5/20 MPa Cement 1 300 kg 300 kg 300 kg 0.135 m3
130mm slump builder’s mix 5.5 1860 kg 1910 kg 1960 kg
water 0.6 200 litres 150 litres 100 litres

25 MPa Cement 1
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340 kg 340 kg 340 kg 0.120 m3
130mm slump builder’s mix 4.75 1835 kg 1885 kg 2035 kg
water 0.55 200 litres 150 litres 100 litres
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NOTE –
(1) Materials are batched in bulk volume except as provided for in 3.3.4.
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(2) SSD is the mix design based around aggregates which are assumed to be saturated inside but have a
dry surface so that the builder's mix neither absorbs water from the mix nor contributes free water to the
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mix.

(3) Damp conditions are considered to be 3 % free moisture in the builder’s mix.
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(4) Wet conditions are 5 % free moisture.

Where a problem is consistently experienced with water demand, the aggregate grading needs to be checked.
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3.3.2 Aggregate
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Aggregate for use with this section shall be supplied as a combined grading of coarse and fine aggregates
complying with table 3.2 except as provided for in 3.3.3. The aggregate supplier shall, when requested,
supply the particle size distribution information of the builder’s mix supplied.
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 NZS 3104:2003

Table 3.2 – Combined grading requirements

Aggregate Size % Passing

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19 mm 100 – 90

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13 mm 100 – 70

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9.5 mm 80 – 55

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4.75 mm 60 – 40
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2.36 mm 52 – 36

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1.18 mm 42 – 26

600 microns 30 – 18

300 microns 18 – 8

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150 microns 5 – 0

3.3.3 Proportion of sand and aggregate

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Where a concrete producer wishes to use separate aggregate and sand materials instead of builder’s
mix, the individual proportions shall be specified by a mix Designer. But the overall yield per bag of
cement listed in table 3.1 for the class of concrete selected shall not be exceeded.
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3.3.4 Weight batching
Where a concrete producer elects to use weight batching and the equipment complies with 2.7, then
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the cement contents of the prescribed mixes in table 3.1 may be reduced by 20 kg and the aggregate
quantities adjusted accordingly.
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3.4 Prescribed concrete mixes

3.4.1 Proportions of materials

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The proportions of materials as shown in table 3.1 shall be batched. The table provides mixes for the
following applications:

10 MPa dry mix 50mm slump Bedding concrete: Fence posts, etc.
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15 MPa 130mm slump General purpose: Footpaths, implement sheds

17.5 and 20 MPa 130mm slump As required for NZS 3604 or NZS 4229
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25 MPa 130mm slump As required for NZS 3604 or NZS 4229 for exposed concrete in
seaspray zone (e.g. dairy shed floors, pig slats, etc.).

NOTE – The proportions for prescribed mixes (P) 17.5 and 20 are identical. The design accuracy for the mixes
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does not warrant amending the proportions.

3.4.2 Methods of volume batching

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Aggregate and cement shall be volume batched using either gauge boxes or buckets. The cement
gauge box or bucket shall be used exclusively for cement.

C3.4.2
Cement should be placed in the volume measure and the measuring container shall be slightly tapped
on the ground. The volume measure should then be topped up if required.

3.4.3 Accuracy
The accuracy of measurement shall be within the limits of table 3.3.

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 NZS 3104:2003

Table 3.3 – Accuracy of measurement

Material Volume

*
Cement ± 2.5 %

d
Water ±2.5 %
Aggregates ±5 %

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3.5 Concrete mixing
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3.5.1 Loading
The initial loading of the mixer shall include 80 % of the estimated water demand given in table 3.1.

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C3.5.1
In wet weather the water content in the builder’s mix will increase, and therefore the mix will require

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less water to be added to achieve a homogenous workable state. Over-dosing the water will reduce
all the important properties of concrete such as strength, durability and abrasion resistance. It will
also increase the amount of shrinkage that will occur.

3.5.2 Remaining water sN

The remaining water shall only be added in sufficient quantities to achieve a homogenous mass of
workable concrete.
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 NZS 3104:2003

4 CONCRETE MIXERS

4.1 General

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4.1.1 Performance

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The performance of concrete mixers both for manufacture and subsequent operation shall comply with

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relevant requirements of this section.

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4.1.2 Operation
Operation and maintenance of concrete mixers shall be conducted in accordance with 2.8.
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4.1.3 Application

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The provisions of this part apply to both batch and continuous mixers.

4.2 Performance

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4.2.1 Mixing
When operated at or below their rated mixing capacity, mixers shall be capable of thoroughly mixing all
the concrete materials, within a specified interval of time, so that the ingredients are uniformly distributed
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throughout the volume of mixed concrete. A mixer shall be deemed to comply with this requirement if:

(a) It is one of a series or a model of which at least one prototype has been tested and found to comply
with all the criteria of 2.15.4, when using a concrete mix with a slump in the range of 40 to 80 mm,
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and has not been altered as to design, or has not undergone a major repair (e.g. design alteration)
of the components of the mixing mechanism, since original manufacture.
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(b) It has undergone a major repair of its components forming the mixing mechanism (e.g. design
alteration) since original manufacture, and since that repair, has been tested and found to comply
with all the criteria of 2.15.4; and
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(c) In both (a) and (b) above, it has been regularly inspected to ensure that the mixing mechanism has
not become worn to a degree, protection to the free edges has not been lost, holes have not formed
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in the rotating parts, and any concrete adhering to the mechanism, or to the interior surface of the
mixing chamber, has been substantially removed.
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4.2.2 Non-complying mixers

Non-complying mixers shall not be used for the supply of concrete. A mixer shall be deemed to be
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non-complying if, for a batch mixer, either one of the following applies:

(a) The minimum mixing time exceeds 5 min;

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(b) The mixer is not capable of operating at more that half the rated mixing capacity.

For a continuous mixer, (b) only applies:

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4.2.3 Mixer maintenance and repair

Mixers shall be regularly cleaned, examined and maintained to prevent the build-up of hardened concrete
in the mixing chamber, or wear of the mixing mechanism, to an extent that each mixer’s efficiency is
affected.

If non-uniformity of mixing due to wear is apparent, the mixer shall be repaired and, if the repair is major
(i.e. design alteration), the mixer shall be retested as set out in 2.15.4 before being reused (see Note).

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 NZS 3104:2003

If minor repairs to the mixer have been carried out, or routine periodic assessment for compliance with
2.15.4 is required, the mixer shall be deemed to comply if it is tested in accordance with this clause and
the test results for slump, air content and mass per unit volume are within the corresponding limits given.

*
NOTE – Uniformity of mixing can be seriously affected by the method of charging the mixer. If wear is small,

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this should be investigated before carrying out repairs or routine uniformity tests on the mixer.

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4.2.4 Identification plates

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Each mixer shall have a metal plate which is clearly inscribed with at least the following information
permanently affixed to it in a prominent place:
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(a) The equipment manufacturer’s name;

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(b) A model and serial number which identifies the particular mixer.

In addition, identification plates for batch mixers and continuous mixers shall be inscribed with the further

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information given in 4.3.5 and 4.4.2 respectively.

4.3 Batch mixers

4.3.1 Mixer controls

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Batch mixers shall be provided with the means for selecting appropriate speeds for mixing, discharging
and, if applicable, agitating each batch.
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4.3.2 Rated mixing capacity

Unless it can be otherwise demonstrated by testing in accordance with 2.15.4, the rated mixing capacity
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of a batch mixer shall be not more than 65 % of the gross internal volume of the mixing chamber. If a
batch mixer is operated as an agitator, the rated agitating capacity for this purpose only may be taken
as not more than 80 % of the gross internal volume of the mixing chamber.
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4.3.3 Minimum mixing criteria

The minimum number of revolutions of the mixing mechanism shall be as determined from the mixer
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manufacturer’s recommendations unless determined in accordance with 4.3.4.

4.3.4 Determination of minimum mixing time or number of revolutions

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The reduced mixer uniformity test referred to in 2.15.4 shall be carried out on a batch mixer for given
concrete mixes:
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(a) To confirm the mixer manufacturer’s recommended minimum number of revolutions or minimum
mixing time at the mixer manufacturer’s rated capacity and mixing speed; or
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(b) To determine an acceptable minimum number of revolutions or minimum mixing time at the mixer
manufacturer’s rated capacity, or at a different working capacity, at the mixer manufacturer’s
recommended mixing speed.
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If the uniformity test is used to confirm a recommended minimum mixing time, the required samples shall
be obtained immediately after the nominated mixing time. If the uniformity test is used to determine an
acceptable minimum mixing time, the acceptable time for a given capacity shall be taken as the least
time at which the uniformity requirements of 2.15.4 are met but in no case shall this be more than 5 min.

4.3.5 Identification plates

Identification plates for batch-mixers shall be in accordance with 4.2.4 and inscribed with the following
additional information (see figure 4.1): ➤

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 NZS 3104:2003

(a) The gross internal volume of the mixing chamber (m3);

(b) The rated mixing capacity (m3);

*
(c) The recommended minimum:

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(i) Number of revolutions of the mixing mechanism required to achieve uniformity, or

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(ii) Mixing time, in minutes, and the corresponding rotational speed of the mixing mechanism, in

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revolutions per minute;
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(d) If the mixer is designed to be used also as an agitator, the rated agitating capacity and speed of the

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mixing mechanism in revolutions per minute.

MANUFACTURER’S NAME

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Manufacturer’s address

SERIAL No.

GROSS MIXER VOLUME

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RATED MIXING CAPACITY* m3

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MIXING SPEED rev/min

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MINIMUM MIXING TIME AT* rev/min min

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RATED AGITATING CAPACITY m3

AGITATING SPEED rev/min

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DATE TESTED*

First
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Latest
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*In accordance with NZS 3104

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Figure 4.1 – Identification plate for mixers

4.4 Continuous mixers

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4.4.1 Charging rate

The rate of charging ingredients into a continuous mixer shall be adjusted so that:

(a) The mixer manufacturer’s specified discharge capacity is not exceeded; and

(b) The mixer uniformity tests, carried out in accordance with 2.15.4, are passed.

4.4.2 Identification plates

Identification plates for continuous mixers shall be in accordance with 4.2.4 and inscribed with the
maximum discharge rate, in tonnes per hour.

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 NZS 3104:2003

© 2003 STANDARDS COUNCIL

Approved by the Standards Council on 24 July 2003 to be a New Zealand

Standard pursuant to the provisions of section 10 of the Standards Act 1988.

First published: 5 September 2003

Reprinted incorporating Amendment No. 1: June 2007
Reprinted incorporating Amendment No. 2: February 2010

The following SNZ references relate to this Standard:

Project No. P 3104

Draft for comment No. DZ 3104
Typeset by: Standards New Zealand
Printed by: The Colour Guy