BS EN196-21pdf PDF
BS EN196-21pdf PDF
BS EN196-21pdf PDF
196-21:1992
Methods of testing
cement —
Part 21: Determination of the chloride,
carbon dioxide and alkali content of
cement
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Cooperating organizations
Contents
Page
Cooperating organizations Inside front cover
National foreword ii
Brief history 2
Foreword 2
Text of EN 196-21 5
National annex NA (informative) Test method for the
alkali content of cement to be used for the purpose of
calculating the reactive alkali content of concrete 16
National annex NB (informative) Committees responsible Inside back cover
National annex NC (informative) Cross-references Inside back cover
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© BSI 01-1999 i
BS EN 196-21:1992
National foreword
This British Standard has been prepared under the direction of the Technical
Sector Board for Building and Civil Engineering. It is the English language
version of EN 196-21:1989 “Methods of testing cement; Determination of the
chloride, carbon dioxide and alkali content of cement”, published by the European
Committee for Standardization (CEN). EN 196-21 was drawn up by Technical
Committee 51, Cement and building limes, as Part 21 of a series on testing
cement which was accepted by CEN on 3 October 1989. The UK gave a negative
vote at the final voting stage, but under the CEN Rules now in force, is bound to
abide by the majority decision and to implement this Part. Thus, the European
test procedures have been introduced, where relevant, into the 1991 revisions of
British Standards for cement BS 12, BS 146, BS 4027, BS 4246, BS 6588 and
BS 6610. This British Standard supersedes clauses 16 and 17 of BS 4550-2 which
are withdrawn.
The UK negative vote on this Part was due to the fact that the European
methods for alkalis give values for Na2O equivalent of cement higher by
approximately 0.025 % absolute than those obtained using either the current BS
or the ASTM methods which have been used in the UK for the purpose of
calculating the “reactive” alkali content of concrete.
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Summary of pages
This document comprises a front cover, an inside front cover, pages i and ii,
the EN title page, pages 2 to 20, an inside back cover and a back cover.
This standard has been updated (see copyright date) and may have had
amendments incorporated. This will be indicated in the amendment table on
the inside front cover.
ii © BSI 01-1999
EUROPEAN STANDARD EN 196-21
NORME EUROPÉENNE
EUROPÄISCHE NORM December 1989
UDC 666.94:691.54:620.1:543.84
Descriptors: Cements, tests, chemical analysis, determination of content, chlorides, carbon dioxide, alkali
English version
Méthodes d’essais des ciments; Détermination Prüfverfahren für Zement; Bestimmung des
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CEN
European Committee for Standardization
Comité Européen de Normalisation
Europäisches Komitee für Normung
2 © BSI 01-1999
EN 196-21:1989
Contents
Page Page
Brief history 2 7.7 Expression of results 13
Foreword 2 7.8 Repeatability and reproducibility 13
1 Object and field of application 5 8 Determination of the alkali content
2 References 5 (alternative method) 13
3 General requirements for testing 5 8.1 Principle 13
3.1 Number of tests 5 8.2 Reagents 13
3.2 Repeatability and reproducibility 5 8.3 Apparatus 14
3.3 Expression of masses, volumes 8.4 Plotting the calibration curve 14
and results 5 8.5 Procedure 14
3.4 Determination of constant mass 5 8.6 Expression of results 14
3.5 Preparation of the cement sample 5 8.7 Repeatability and reproducibility 15
3.6 Reagents 5 Figure 1 — Apparatus for the
3.7 Volumetric glassware 6 determination of the carbon dioxide content
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(reference method) 8
4 Determination of the chloride content 6
Figure 2 — Apparatus for the
4.1 Principle 6
determination of the carbon dioxide content
4.2 Reagents 6 (alternative method) 10
4.3 Apparatus 6 Table 1 — Volumes of solutions for the
4.4 Procedure 6 preparation of calibration solutions and their
4.5 Expression of results 6 sodium oxide and potassium oxide
concentrations 12
4.6 Repeatability and reproducibility 7
Table NA.1 — Solutions for checking
5 Determination of the carbon purity of calcium solution 17
dioxide content reference method) 7
Table NA.2 — Solutions for calibrating
5.1 Principle 7
flame photometer 18
5.2 Reagents 7
5.3 Apparatus 7
5.4 Procedure 8
5.5 Expression of results 9
5.6 Repeatability and reproducibility 9
6 Determination of carbon dioxide
content (alternative method) 9
6.1 Principle 9
6.2 Reagents 9
6.3 Apparatus 9
6.4 Procedure 9
6.5 Expression of results 10
6.6 Repeatability and reproducibility 10
7 Determination of the alkali content
(reference method) 11
7.1 Principle 11
7.2 Reagents 11
7.3 Apparatus 11
7.4 Preparation of calibration solutions
and calibration graphs 11
7.5 Dissolution of the test portion 11
7.6 Procedure 12
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4
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BS EN 196-21:1992
1 Object and field of application If the results of two determinations differ by more
than twice the standard deviation for repeatability,
This European Standard lays down the methods for
repeat the test and take the mean of the two closest
the determination of the chloride, carbon dioxide
values as the result.
and alkali content of cement.
3.4 Determination of constant mass
The standard describes the reference methods and,
in certain cases, an alternative method which can be Determine constant mass by making
considered as giving equivalent results. successive 15 min ignitions followed each time by
If other methods are used, their results shall be cooling and then weighing. Constant mass is
shown to be equivalent to the results given by the reached when the difference between two successive
reference methods. In the case of a dispute, only the weighings is less than 0,0005 g.
reference methods are applicable. 3.5 Preparation of the cement sample
This standard applies to cements and also to their Before starting the determinations, treat the
constituent materials, such as clinker and laboratory sample, taken in accordance with
blastfurnace slag. EN 196-7, as follows to obtain a sample for testing.
Take approximately 100 g of the sample using a
2 References sample divider or by quartering. Sieve this portion
EN 196-2, Methods of testing cement — Chemical on a 150 µm or 125 µm sieve until the residue
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3)
As defined in ISO 3534.
© BSI 01-1999 5
EN 196-21:1989
The degree of dilution is always given as a 4.3.4 Filter paper, coarse (pore diameter
volumetric sum, for example, dilute hydrochloric approximately 20 µm).
acid 1 + 2 means that 1 volume of concentrated 4.3.5 5 ml pipette
hydrochloric acid is to be mixed with 2 volumes of
water. 4.4 Procedure
6 © BSI 01-1999
EN 196-21:1989
4)
The absorbent can be obtained ready for use.
© BSI 01-1999 7
EN 196-21:1989
5.3.2 Balance, capable of weighing to the Condition the closed absorption tubes (G) and (H)
nearest 0,0001 g. for 15 min in the balance case in order to achieve
5.3.3 Electric oven, which can be set at (105 ± 5) °C temperature equilibrium. Then weigh each tube
and at (155 ± 5) °C. separately. Shut off the flow of gas and attach the
tubes to the apparatus as shown in Figure 1.
5.3.4 Desiccator, containing anhydrous magnesium
perchlorate (Mg(ClO4)2). Wear protective gloves when carrying out this
operation.
5.4 Procedure
Then reopen the gas flow. After 10 min close
Weigh (1 ± 0,05) g of cement and place it in a absorption tubes (G) and (H), remove them, place
dry 100 ml distillation flask. Connect the flask to them in the balance case for 15 min and then weigh
the apparatus (5.3.1) as shown in Figure 1, but them separately. Repeat the passage of gas, removal
without the two absorption tubes (G) and (H). Pass and weighing of absorption tubes (G) and (H) for as
a current of carbon dioxide-free gas through the long as is required for the results of two successive
apparatus for 15 min at approximately 3 bubbles weighings of a tube not to differ by more
per second (bubble counter) via the connecting tube than 0,0005 g.
onto B2 (branch onto B1, Mohr clip closed). Release
the Mohr clip and remove the gas supply from the If the change in mass of the absorption tubes (G)
funnel (O). Add 30 ml concentrated phosphoric acid and (H) remains greater than 0,0005 g, renew the
absorbents in tubes (E) and (F).
into the dropping funnel and reconnect the gas
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Figure 1 — Apparatus for the determination of the carbon dioxide content (reference method)
8 © BSI 01-1999
EN 196-21:1989
Attach the weighed absorption tubes (G) and (H) to 6.2 Reagents
the apparatus, as shown in Figure 1. 6.2.1 Mercuric (II) chloride (HgCl2).
Open the funnel tap and allow the phosphoric acid
6.2.2 Absorbent for carbon dioxide, synthetic
to drop into the distillation flask (A). After the silicates with a particle size between 0,6 mm
reaction has ceased, heat the contents of the flask to and 1,2 mm5) impregnated with sodium hydroxide,
boiling and boil gently for 5 min. Maintain the gas
(NaOH).
flow through the apparatus until the flask has
cooled to room temperature. 6.2.3 Concentrated sulphuric acid (H2SO4).
Close absorption tubes (G) and (H), remove them 6.2.4 Dilute sulphuric acid 1 + 4.
and place them in the balance case for 15 min and 6.2.5 Absorbent for water, anhydrous magnesium
then weigh them separately. The increase in mass of perchlorate (Mg(ClO4)2) with a particle size
each tube is used for the calculation of the carbon between 0,6 mm and 1,2 mm.
dioxide content (see 5.5).
6.3 Apparatus
The carbon dioxide is practically completely
absorbed by tube (G). If the increase in mass of 6.3.1 Apparatus for the determination of the carbon
tube (H) exceeds 0,0005 g, renew the absorbent in dioxide content. The apparatus is shown in Figure 2.
tube (G) and start the test again. A small vacuum pump is used to generate reduced
pressure in the apparatus.
5.5 Expression of results
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5)
See page 6.
© BSI 01-1999 9
EN 196-21:1989
10 © BSI 01-1999
EN 196-21:1989
method. If the alkali content of a reagent acid 1 + 19 and dilute phosphoric acid 1 + 19 listed
exceeds 0,01 %, the batch concerned is unsuitable in Table 1. The volumes listed in lines 1 to 8 shall be
and shall therefore be replaced by another which made up to 1 000 ml with water. Store these
shall be tested in the same way. calibration solutions in polyethylene bottles.
7.2.2 Concentrated hydrochloric acid (HCl). Spray the calibration solutions into the flame of the
flame photometer (7.3.3). Spray the blank
7.2.3 Dilute hydrochloric acid 1 + 19. solution (Table 1, line 1) first and set the indication
7.2.4 Concentrated phosphoric acid (H3PO4). on the apparatus to 0. Then spray the other
calibration solutions in the order of increasing
7.2.5 Dilute phosphoric acid 1 + 19; store this
solution in a polyethylene flask. concentration (lines 2 to 8). Measure the intensities
for Na2O at 589 mm and for K2O at 768 nm.
7.2.6 Concentrated nitric acid (HNO3).
Plot graphs of the measured intensities against the
7.2.7 Concentrated perchloric acid (HClO4). corresponding concentrations of sodium oxide and
7.2.8 Concentrated hydrofluoric acid (HF). potassium oxide in the calibration solutions.
7.2.9 Sodium chloride (NaCl), dried at 105 °C to 7.5 Dissolution of the test portion
constant mass. 7.5.1 Cements completely soluble in acid
7.2.10 Potassium chloride (KCl), dried at 105 °C to (content of insoluble residue < 3 %)
constant mass. Weigh 0,1 g cement into a 50 ml beaker, make into
7.2.11 Alkali stock solution. Weigh about 0,566 g of a slurry with 10 ml of water and add 10 ml of dilute
sodium chloride and about 0,475 g of potassium hydrochloric acid 1 + 19. Warm the mixture until
chloride, transfer them to a 1 000 ml volumetric the cement has dissolved, breaking any lumps down
flask, add 100 ml each of dilute hydrochloric with a glass rod. Filter the suspension through the
acid 1 + 19 and dilute phosphoric acid 1 + 19, filter paper (7.3.5) into a 100 ml volumetric flask
dissolve and make up to the mark with water. This washing through with boiling water. Wash the filter
solution contains approximately 0,300 g each of paper and residue with boiling water until there is a
Na2O and K2O. The actual contents can be quantity of approximately 80 ml in the 100 ml
determined from the original quantities from the volumetric flask. Then allow the filtrate and
following formulae: washing water to cool to ambient temperature.
Add 10 ml of dilute phosphoric acid 1 + 19 to the
K2O (in g/l) = 0,6138 × actual mass of solution, make up to the mark and mix thoroughly.
potassium chloride in g (4)
Na2O (in g/l) = 0,5303 × actual mass of
sodium chloride in g (5)
© BSI 01-1999 11
EN 196-21:1989
(7)
Table 1 — Volumes of solutions for the preparation of calibration solutions and their sodium
oxide and potassium oxide concentrations
Line Alkali stock solution Dilute hydrochloric acid Dilute phosphoric acid Na2O and K2O
(7.2.11) 1 + 19 1 + 19 concentrations
ml ml ml mg/l
1 — 100,0 100,0 Blank solution
2 3,3 99,6 99,6 1,0
3 8,3 99,1 99,1 2,5
4 16,7 98,3 98,3 5,0
5 25,0 97,5 97,5 7,5
6 33,3 96,6 96,6 10,0
7 41,7 95,8 95,8 12,5
8 50,0 95,0 95,0 15,0
6) Perchloric
acid vapours form explosive mixtures with organic materials. It is therefore necessary to take special precautionary
measures when working with perchloric acid: the use of fume cupboards flushed with water and a general ban on the use of
organic substances in the same fume cupboard.
12 © BSI 01-1999
EN 196-21:1989
CNa 2 O is the sodium oxide concentration of Dissolve 0,610 g of lithium chloride, 0,2542 g of
the measuring solution as calculated sodium chloride and 0,1907 g of potassium chloride
by formula (6) (in mg/l); in water in a 1 000 ml volumetric flask and make up
to the mark.
CK2 O is the potassium oxide concentration
of the measuring solution as 8.2.9 Caesium chloride (CsCl).
calculated by formula (7) (in mg/l). 8.2.10 Aluminium nitrate (Al(NO3)3.9H2O).
8.2.11 Buffer solution7)
The mean of the two results for each oxide shall be
rounded to the nearest 0,01 %. Dissolve 50 g of caesium chloride and 250 g of
aluminium nitrate in water and make up
The total alkali content, A, is obtained by converting
to 1 000 ml.
the potassium oxide content to equivalent sodium
oxide from the formula:
7)
These solutions can also be obtained made up ready for use.
© BSI 01-1999 13
EN 196-21:1989
8.3 Apparatus Spray the calibration solutions into the flame of the
8.3.1 Balance, capable of weighing to the flame photometer (8.3.3). Spray the blank
nearest 0,0001 g. solution 1 first and set the indication on the
apparatus to 0. Then spray the other
8.3.2 Electric oven, which can be set at (105 ± 5) °C calibration solutions in order of increasing
and at (120 ± 5) °C. concentration (2 to 7). Measure the intensities
8.3.3 Flame photometer, capable of measuring the for Na2O at 589 nm and for K2O at 768 nm. Plot
intensities of the sodium line at 589 nm and the graphs of the measured intensities against the
potassium line at 768 nm. The flame photometer corresponding concentrations of sodium oxide and
shall be operated with a propane-air flame at a potassium oxide in the calibration solutions.
relatively low temperature in order to avoid If a sufficiently stable photometer is used, it is only
distortion of the determination by alkaline earths. necessary to establish the calibration curves from
8.3.4 Filter paper, medium porosity (pore diameter time to time. However, the values measured for
approximately 7 µm). flasks 1 and 7 shall be checked for each analysis.
8.3.5 Platinum dish. 8.5 Procedure
8.3.6 Heating lamp. 8.5.1 Cements completely soluble in acid
8.3.7 Calibrated burette. (content of insoluble residue < 3 %)
Weigh 0,2 g cement into the platinum dish (8.3.5),
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14 © BSI 01-1999
BS EN 196-21:1992
© BSI 01-1999 15
BS EN 196-21:1992
8) There should be a suitably rated fuse in the circuit to protect the power supply.
9) With a current of 8 A approximately 20 g of aluminium is dissolved in 21/2 h. A lower current for a longer time is permissible.
16 © BSI 01-1999
BS EN 196-21:1992
Maintain the volume at about 600 ml by NOTE 1 For instruments using internal standardization, add
adding water as necessary. When all the metal the internal standard solution to the calibration solutions in
accordance with the manufacturers’ instructions.
has dissolved, cool the solution and dilute
NOTE 2 In some cases different Na 2O and/or K 2O
to 1 000 ml. concentration ranges may be required. Should this be necessary,
NA.3.4 Calcium solution, (6.3 g of CaO per litre.) modify the alkali contents of the calibration solutions as
appropriate but take the Al, Ca and HNO3 additions from
Weigh 11.25 g of analytical reagent grade, or purer. Table NA.2. The concentration of the scale-100 solution should
CaCO3 into a beaker, cover with 100 ml of water and not exceed that recommended by the instrument manufacturer.
carefully add 25 ml of HNO3. When solution is
complete dilute to 1 000 ml with water. NA.5 Procedure
Test for sodium and potassium contamination by NA.5.1 Determination of alkalis soluble in
the following procedure. nitric acid
Prepare solutions A, B and C, using the quantities NOTE This procedure is generally applicable to cements, and
given in Table NA.1. other materials, which are almost completely decomposed by
nitric acid solution.
With the sodium light filter in place, set the flame
Weigh out 500 mg of sample into a beaker made
photometer to read 0 with solution A and 100 with
from a material which will not yield sodium or
solution B. Spray solution C and record the reading.
potassium to the solution. Add about 50 ml of cold
Replace the sodium light filter by the potassium
water, disperse the powder by swirling and add 5 ml
light filter and repeat the procedure. If readings
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A 0 0 50 0 5 500
B 25 50 50 0 5 500
C 0 0 50 50 5 500
10) Beforemaking up to volume, add, where necessary, sufficient of the standard calcium solution to bring the concentration of
calcium oxide in the diluted solution to approximately 630 mg/l, and, for instruments using internal standardization, also add
the internal standard solution in accordance with the manufacturer’s instructions.
© BSI 01-1999 17
BS EN 196-21:1992
ml ml ml ml ml ml ml ml
solution and take several readings, checking and never be constructed in wood but polyvinyl chloride
adjusting if necessary, the 0 and 100 settings and stainless steel have been found suitable. All
between each reading. Replace the sodium light materials of construction should be non-absorbent
filter by the potassium light filter and again set the and interior surfaces should be free from crevices
flame photometer to read 0 with scale-zero solution and ledges that could prevent complete washing
and 100 with scale-100 solution. Spray the sample down. Guidance on the suitability of a fume
solution and take several readings, checking, and cupboard for use with perchloric acid should be
adjusting if necessary, the 0 and 100 settings sought from the manufacturer.
between each reading. Recommendations on all aspects of fume cupboards
If the sample gives a reading of more than 100 for are given in BS 725811).
either sodium or potassium, transfer 50 ml of Add 5 ml of nitric acid, cool and transfer to a 500 ml
sample solution to a 100 ml graduated flask, dilute volumetric flask. Add 50 mL of the aluminium
to the mark with scale-zero solution and re-spray. In solution, dilute to 500 ml with water12) and mix
exceptional cases a further dilution may be thoroughly. Then repeat the procedure in NA.5.1
required. from the second paragraph onwards.
NA.5.2 Determination of total alkalis Make blank determinations following the above
Weigh 500 mg of sample into a platinum basin and procedure with no sample present.
remove carbon or carbonaceous matter by careful
ignition at 925 ± 25 °C. Cool the sample and NA.6 Calculation
add 20 ml of water and 10 ml of perchloric acid. Stir, From the respective calibration graphs for Na2O
add 20 ml of hydrofluoric acid and evaporate the and K2O (see NA.4) convert flame photometer
solution to strong fumes of perchloric acid in a readings to concentrations (milligrams per litre).
mechanically ventilated fume cupboard. Add 20 ml For the determination of total alkalis deduct the
of water and 5 ml of perchloric acid and again blank determinations from the readings given
evaporate until fumes just cease to be emitted. by Na2O and K2O respectively.
Where dilution of the original solution has been
made apply the dilution factor.
11)
BS 7258 Laboratory fume cupboards.
12) Beforemaking up to volume, add, where necessary, sufficient of the standard calcium solution to bring the concentration of
calcium oxide in the diluted solution to approximately 630 mg/l, and, for instruments using internal standardization, also add
the internal standard solution in accordance with the manufacturer’s instructions.
18 © BSI 01-1999
BS EN 196-21:1992
© BSI 01-1999 19
BS EN 196-21:1992
Committees responsible
The United Kingdom participation in the preparation of this European Standard was entrusted by the
Technical Sector Board for Building and Civil Engineering (B/-) to Technical Committee B/516 upon which
the following bodies were represented:
Cross-references
20 © BSI 01-1999
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