Bsi bs en 00480 12 2005

BRITISH STANDARD

Admixtures for
concrete, mortar
and grout — Test
methods —
Part 12: Determination of the alkali
content of admixtures

The European Standard EN 480-12:2005 has the status of a
British Standard

ICS 91.100.10; 91.100.30

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BS EN
480-12:2005


BS EN 480-12:2005

National foreword
This British Standard is the official English language version of
EN 480-12:2005. It supersedes BS EN 480-12:1998 which is withdrawn.
The UK participation in its preparation was entrusted by Technical Committee
B/517, Concrete, to Subcommittee B/517/3, Admixtures, which has the
responsibility to:
—

aid enquirers to understand the text;

—

present to the responsible international/European committee any
enquiries on the interpretation, or proposals for change, and keep UK
interests informed;

—

monitor related international and European developments and
promulgate them in the UK.

A list of organizations represented on this subcommittee can be obtained on
request to its secretary.
Cross-references
The British Standards which implement international or European
publications referred to in this document may be found in the BSI Catalogue
under the section entitled “International Standards Correspondence Index”, or
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Summary of pages
This document comprises a front cover, an inside front cover, the EN title page,
pages 2 to 9 and a back cover.
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document was last issued.

Amendments issued since publication
This British Standard was
published under the authority
of the Standards Policy and
Strategy Committee
on 25 November 2005
© BSI 25 November 2005

ISBN 0 580 47319 8

Amd. No.

Date

Comments


EN 480-12

EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM

October 2005

ICS 91.100.10; 91.100.30

Supersedes EN 480-12:1997

English Version

Admixtures for concrete, mortar and grout - Test methods - Part
12: Determination of the alkali content of admixtures
Adjuvants pour béton, mortiers et coulis - Méthodes d'essai
- Partie 12: Détermination de la teneur en alcalis dans les
adjuvants

Zusatzmittel für Beton, Mörtel und Einpressmörtel Prüfverfahren - Teil 12: Bestimmung des Alkaligehalts von
Zusatzstoffen

This European Standard was approved by CEN on 28 July 2005.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the Central Secretariat or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: rue de Stassart, 36

© 2005 CEN

All rights of exploitation in any form and by any means reserved
worldwide for CEN national Members.

B-1050 Brussels

Ref. No. EN 480-12:2005: E


EN 480-12:2005 (E)

Contents
Page
Foreword ..........................................................................................................................................................3
1

Scope ...................................................................................................................................................4

2

Normative references .........................................................................................................................4

3

Principle...............................................................................................................................................4

4

Reagents..............................................................................................................................................5

5

Apparatus ............................................................................................................................................6

6

Preparation of calibration graphs ......................................................................................................6

7

Test procedure ....................................................................................................................................6

8

Test report ...........................................................................................................................................8

Bibliography.....................................................................................................................................................9

2


EN 480-12:2005 (E)

Foreword
This European Standard (EN 480-12:2005) has been prepared by Technical Committee CEN/TC 104
“Concrete and related products”, the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by April 2006, and conflicting national standards shall be withdrawn at the
latest by April 2006.
It has been drafted by Subcommittee 3 (SC 3) of TC 104 "Admixtures for concrete, mortar and grout".
This document is part of the series EN 480 "Admixtures for concrete, mortar and grout – Test methods" which

comprises the following
Part 1

Reference concrete and reference mortar for testing

Part 2

Determination of setting time

Part 4

Determination of bleeding of concrete

Part 5

Determination of capillary absorption

Part 6

Infrared analysis

Part 8

Determination of the conventional dry material content

Part 10 Determination of water soluble chloride content
Part 11 Determination of air void characteristics in hardened concrete
Part 12 Determination of the alkali content of admixtures
Part 13 Reference masonry mortar for testing mortar admixtures
Part 14 Admixtures for concrete, mortar and grout - Test methods - Part 14: Measurement of corrosion

susceptibility of reinforcing steel in concrete - Potentiostatic electro-chemical test method 1)
This document is applicable together with the other standards of the EN 480 series.
This document supersedes EN 480-12:1997.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland
and United Kingdom.

1) This part is under preparation

3


EN 480-12:2005 (E)

1

Scope

This document specifies a method for the determination of the alkali (sodium and potassium) content of
admixtures for concrete, mortar and grouts in accordance with the series EN 934.

2

Normative references

The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.

EN 196-2, Methods of testing cement – Determination of the chloride, carbon dioxide and alkali content of
cement.
ISO 648, Laboratory glassware – One-mark pipettes.
ISO 1042, Laboratory glassware – One-mark volumetric flasks.

3

Principle

An atomic absorption spectrophotometer is used to measure the sodium and potassium in dilute nitric acid
extracts from admixtures. The extract is nebulised into an air/acetylene flame and the absorption of sodium or
potassium radiation as it passes through the flame is measured. The amount of absorption is directly
proportional to the sodium or potassium content of the extract at low concentrations. The sodium and
potassium contents are separately measured and their sum, proportioned by molecular mass, is reported as
the total equivalent Na2O (alkali) content.
As an alternative to an atomic absorption spectro-photometer a suitable calibrated flame photometer can be
used for the determination of sodium and potassium in the test solutions prepared in accordance with this
document.

4


EN 480-12:2005 (E)

4

Reagents

4.1 Concentrated nitric acid, analytical reagent diluted 1: 1 with water (4.2).
4.2 Distilled, de-ionised or demineralised water. The same source of water shall be used for preparation of

calibration solutions and sample extracts.
4.3 Sodium stock solution (100 mg Na2O per litre). Dissolve 0,188 g sodium chloride, analytical reagent grade,
dried at (105 ± 5) °C to constant mass, in water (4.2), dilute to 1 litre in a volumetric flask (5.2) with water2).
4.4 Potassium stock solution (100 mg K2O per litre). Dissolve 0,158 g potassium chloride, analytical reagent
grade, dried at (105 ± 5) °C to constant mass, in water (4.2), dilute to 1 litre in a volumetric flask (5.2) with
water2).
4.5 Calibration solution3). Measure the required volume of stock solution shown in Table 1 with a pipette and
nitric acid with a plastic measuring cylinder. Transfer to a 1 litre graduated volumetric flask and dilute to the
mark with water. Mix thoroughly and transfer to a clean dry plastic bottle with a water and air tight closure (5.5).
Table 1: Calibration solutions

2)

Na2O and K2O
concentration

Sodium stock solution
(4.3)

Potassium stock solution
(4.4)

Nitric Acid (4.1)

mg/l

ml

ml

ml

0

0

0

10

2,5

25

25

10

5

50

50

10

Commercially available calibrated solutions for spectroscopic applications may be used.

3) The volumes of stock solutions given in Table 1 may not be appropriate when commercially available spectroscopic
solutions are used. In addition some atomic absorption spectrophotometers may require a smaller range of Na2O and K2O

concentration for calibration and use. In this case modify the calibration solutions accordingly.

5


EN 480-12:2005 (E)

5

Apparatus

5.1 Balance with a capacity of up to 200 g readable to 0,1 mg.
5.2 100 ml and 1 litre volumetric flasks of class A in accordance with ISO 1042.
5.3 Calibrated pipettes of class A in accordance with ISO 648.
5.4 10 ml and 25 ml measuring cylinders.
5.5 1 litre plastic bottles with water and air tight closure. The plastic shall be such that no sodium or potassium
is leached into 1 % nitric acid solution over a period of 6 months.
5.6 Atomic absorption spectrophotometer (AAS) equipped with burners suitable for air/acetylene flames and
with a combination Na/K hollow cathode lamp or separate Na and K lamps.
5.7 A flame photometer (according to EN 196-2) if alternatively used in accordance with Clause 3.

6

Preparation of calibration graphs

Operate the AAS or the flame photometer in accordance with the manufacturer's instructions. Whilst spraying
water adjust the wave length setting around 589 nm (for Na) to give the maximum signal on the detector.
Spray the 5,0 mg/l calibration solution and adjust burner height and acetylene flow to give maximum
absorption. Spray the 0 mg/l solution and adjust the gain control to give 0 % absorption and then in turn spray
the other calibration solutions and record the absorption for each one.

Repeat the operation at a wavelength setting around 768 nm (for K).
Some instruments may be used in direct readout concentration mode. When this procedure is used follow the
manufacturer's calibration instructions.

7

Test procedure

7.1 Preparation of test solution
7.1.1

Liquid admixture

Mix the samples thoroughly and transfer approximately 1 ml to a pre-weighed weighing boat. Record the mass
of admixture sample in mg to the nearest 0,1 mg (m1).
Transfer to a 1 litre volumetric flask (5.2) with 150 to 250 ml water (4.2) and add 10 ml nitric acid. Dilute to the
mark with water. Mix thoroughly.
7.1.2

Powder admixtures

Mix the sample thoroughly and weigh approximately 1 g recording the actual mass in mg to 0,1 mg (m1).
Transfer to a 500 ml glass beaker, add 150 to 250 ml water (4.2)) and 10 ml nitric acid (4.1)). Heat to near
boiling on a hot plate and maintain at near boiling for (15 ± 5) minutes.
Remove from the source of heat and cool to room temperature.
Complete dissolution is not necessary. If any insoluble residue remains, filter the solution through a medium
grade filter paper and wash thoroughly with water collecting the filtrate and washings in the volumetric flask.

6

EN 480-12:2005 (E)

Transfer to a 1 litre volumetric flask (5.2)), dilute to the mark with water (4.2)) and mix thoroughly.
7.2 Measurement of sodium and potassium

Operate the AAS in accordance with the manufacturer's instructions with the Na/K lamp in place. Whilst
spraying water adjust the wave length setting around 589 nm (for Na) to give the maximum signal to the
detector.
Use the burner height and fuel settings established in the calibration procedure. Adjust the gain control to give
0 % absorption whilst spraying the 0 mg/l calibration solution.
Spray one or more calibration solutions to confirm that the calibration graph is valid. If necessary prepare a
new graph. Spray the sample solution and record the absorption. Refer to the calibration graph and record the
concentration of the sample solution in mg Na2O/litre.
If the absorption is off scale prepare a diluted extract by transferring 10,0 ml of the sample solution into a
100 ml volumetric flask and dilute to the mark with the 0 mg/l calibration solution i.e. dilution D = 10.
Mix thoroughly and repeat the procedure. Further dilutions may be required. Record mass m2 of Na2O in mg in 1
litre of solution.
Reset the wave length control to around 768 nm (for K) and repeat the above procedure. Record mass m3 of
K2O in mg in 1 litre of solution.
7.3 Results

Calculate the Na2O and K2O content of the admixture from the following equations:

Na2 O content =

K 2 O content =

m2 x 100 D % by mass
m1

m3 x 100 D % by mass
m1

(1)

(2)

Where
m1 mass of admixture sample in mg
m2 mass of Na2O in mg
m3 mass of K2O in mg
and
D

the dilution used if necessary.

Calculate the total equivalent alkali content of the admixture from the following equation:
Total Na2O equivalent = Na2O content + 0,658 K2O content % by mass
Report the total Na2O equivalent content in percent per mass to the nearest 0,1 %.
NOTE
From 12 sets of results from different laboratories, after rejecting one set as outliers, the coefficient of variation
was found to be 5 % of the mean for alkali contents in a range from 1,0 % to 3,5 % Na2O equivalent.

7


EN 480-12:2005 (E)

8

Test report

a)

Name or code of admixture tested (with information relating to its marking);

b)

date of the test;

c)

Name of the laboratory;

d)

Name of operator;

e)

Type of the equipment;

f)

Origin of the sample and date when taken;

g)

Sodium oxide content;

h)

Potassium oxide content;

i)

Sodium oxide equivalent content.

8


EN 480-12:2005 (E)

Bibliography

[1]

EN 934-2, Admixtures for concrete, mortar and grout – Part 2: Concrete admixtures – Definitions,
requirements, conformity, marking and labelling.

[2]

EN 934-3, Admixtures for concrete, mortar and grout – Part 3: Admixtures for mortar - Definitions,
requirements, conformity, marking and labelling.

[3]

EN 934-4, Admixtures for concrete, mortar and grout – Part 4: Admixtures for grout for prestressing
tendons - Definitions, requirements, conformity, marking and labelling.

[4]

EN 934-5, Admixtures for concrete, mortar and grout – Part 5: Admixtures for sprayed concrete Definitions, requirements, conformity, marking and labelling.

9


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BS EN
480-12:2005

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