Bsi bs en 00480 12 2005

untitled BRITISH STANDARD BS EN 480 12 2005 Admixtures for concrete, mortar and grout — Test methods — Part 12 Determination of the alkali content of admixtures The European Standard EN 480 12 2005 ha[.]

BRITISH STANDARD BS EN

480-12:2005

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

12&23<,1*:,7+287%6,3(50,66,21(;&(37$63(50,77('%<&23<5,*+7/$:

This British Standard was

published under the authority

of the Standards Policy and

Strategy Committee

on 25 November 2005

© BSI 25 November 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EN 480-12:2005 It supersedes BS EN 480-12:1998 which is withdrawn The UK participation in its preparation was entrusted by Technical Committee B/517, Concrete, to Subcommittee B/517/3, Admixtures, which has the responsibility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:

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

by using the “Search” facility of the BSI Electronic Catalogue or of British

Standards Online

This publication does not purport to include all the necessary provisions of a contract Users are responsible for its correct application

Compliance with a British Standard does not of itself confer immunity from legal obligations.

— 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

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

The BSI copyright notice displayed in this document indicates when the document was last issued

Amendments issued since publication

EUROPEAN STANDARD

NORME EUROPÉENNE

EUROPÄISCHE NORM

EN 480-12

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

C O M I T É E U R O P É E N D E N O R M A L I S A T I O N

E U R O P Ä IS C H E S K O M IT E E FÜ R N O R M U N G

Management Centre: rue de Stassart, 36 B-1050 Brussels

© 2005 CEN All rights of exploitation in any form and by any means reserved

worldwide for CEN national Members. Ref No EN 480-12:2005: E

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

EN 480-12:2005 (E)

3

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

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

EN 480-12:2005 (E)

5

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

Na2O and K2O

concentration

Sodium stock solution

(4.3)

Potassium stock solution

(4.4) Nitric Acid (4.1)

2) 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 Na 2 O and K 2 O concentration for calibration and use In this case modify the calibration solutions accordingly.

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

EN 480-12:2005 (E)

7

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:

mass

by

% 100 x

= content

O

Na

1

2

m

mass

by

% 100 x

= content

O

K

1

3

m

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 % Na 2 O equivalent

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

EN 480-12:2005 (E)

9

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

BS EN

480-12:2005

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