KENYA STANDARD                     KS 2177:  2017 
                
   
Kenya Standard           KS 2769 -12:2018  
 
 
 
 
 
 
  
 
 
 
 
 
 
 
 
Admixtures for concrete, mortar and grout 
Test methods Part 12: Determination of the 
alkali content of admixtures   
 
 
 
 
 
 
 
 
©KEBS 20 18                        First Edition  2018 
 
 
 
 
 
 
 
 
 
 
 
 
 
 KS 2177: 2017                                                                                                            
 
ii                     © KEBS 2017 — All rights reserved   
TECHNI CAL COMMITEE REPRESENTATION  
 
The following organizations were represented on the Technical Committee:  
 
1. Architectural Association of  Kenya  
2. Bamburi Cement  
3. CHRYSO Eastern Africa Limited  
4. Concrete Products (K)Ltd  
5. Consumer Information Network  
6. Howards Humpreys E ast Africa LTD  
7. Institute of quantity surveyors of Kenya  
8. Kenya Industrial Research and Development Institute (KIRDI  
9. Kenya Institute of Highways and Building Technology (KIHBT)  
10. Ministry of Transport, Infrastructure, Housing and Urban Development.  
11. National En vironment Management Authority  
12. National Housing Corporation  
13. Technical University of Kenya  
14. University of Nairobi  
15. Kenya Bureau of Standards — Secretariat  
 
 
 
 
 
 
 
 
 
 
 
REVISION OF KENYA STANDARDS  
 
In order to keep abreast of progress in industry, Kenya Standard s shall be regularly reviewed. Suggestions 
for improvements to published standards, addressed to the Managing Director, Kenya Bureau of Standards, 
are welcome.  
 
 
 
 
 
 
 
 
 
 
© Kenya Bureau of Standards, 20 17 
  
Copyright. Users are reminded that by virtue of Se ction 25 of the Copyright Act, Cap. 12 of 2001  of the Laws of Kenya, copyright 
subsists in all Kenya Standards and except as provided under Section 26 of this Act, no Kenya Standard produced by Kenya Bure au of 
Standards may be reproduced, stored in a retr ieval system in any form or transmitted by any means without prior permission in writing 
from the Managing Director . 
 
 
 
 
 
 
 
 
 
 KENYA STANDARD                                  KS 2177 : 2017 
                
 © KEBS 2017 — All rights reserved            iii  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Admixtures for concrete, mortar and grout 
Test methods Part 12: Determination of the 
alkali content of adm ixtures   
 
 
 
 
 
KENYA BUREAU OF STANDARDS (KEBS)  
 
Head Office:  P.O. Box 54974, Nairobi -00200, Tel.: (+ 254 020 ) 605490, 602350, Fax: (+254 020 ) 604031  
E-Mail: info@kebs.org,  Web:http://www.kebs.org   
 
Coast Region     Lake Region          Rift Valley Region  
P.O. Box 99376, Mombasa -80100   P.O. Box 2949, Kisumu -40100        P.O. Box 2138, Nakuru -20100  
Tel.: (+ 254 041 ) 229563, 230939/40  Tel.: (+254 057) 23549, 22396        Tel.: (+254 051) 210553, 210555  
Fax: (+254  041) 229448    Fax: (+254 057) 21814         
 
 
 
 
 
 
 
 
 
 KS 2177: 2017                                                                                                            
 
iv                     © KEBS 2017 — All rights reserved  Foreword  
 
This Kenya Standard was revised  by the Concrete Technical Committee, under the guidance of the 
standards Projects Committee, and it is in accordance with the procedures of the  Kenya  Bureau  of 
Standards .  
This Kenya Standard is part of the seri es KS 2769  Admixtures for concrete, mortar and grout — Test 
methods which comprise  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: Determination of the effect on corrosion susceptibility of reinforcing steel by potentiostatic  
Electro -chemical  test 
 
— Part 15: Reference concrete and method for testing viscosity modifying admixtures  
 
This standard is applicable together with the standards of the series KS 2770  Admixtures for concrete, 
mortar  and grout.  
 
. 
 
 KENYA STANDARD                                  KS 2177 : 2017 
                
 © KEBS 2017 — All rights reserved         
   5 BRITISH STANDARD  
KENYA  STANDARD                       KS 2769 -12:2018  
 
Admixtures for concrete, mortar a n d  g r o u t  T e s t  methods 
Part 12: Determination of the alkali content of admixtures  
 
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 KS 2770 . 
 
2.  Normative references  
The following referenced documents are indispensable for the application of this document. For dated 
references, only the edition cited applies. For u ndated references, the latest edition of the referenced 
document (including any amendments) applies.  
 
EAS 148 -2, Cement — Test methods — Part 2: Chemical analysis  
 
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 
potassi um 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, pro portioned by molecular mass, is reported 
as the total equivalent Na 2O(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 tes t solutions prepared in accordance with this 
document.  KS 2177: 2017                                                                                                    
        
 
6                     © KEBS 2017 — All rights 
reserved  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 calibrat ion solutions and sample extracts.  
 
4.3. Sodium stock solution (100 mg Na 2O 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 K 2O 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 dr y 
plastic bottle with a water and air tight closure (5.5).  
 
 
Table 1: Calibration solutions  
Na2O and K 2O  
concentration  Sodium stock solution  
(4.3) Potassium stock solution  
(4.4)  Nitric Acid 
(4.1) 
mg/I ml ml ml 
0 0 0 10 
2,5 25 25 10 
5 50 50 10 
 
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 sp ectrophotometers may require a 
smaller range of Na 2O and K 2O concentration for calibration and use. In this case modify the calibration 
solutions accordingly.  KENYA STANDARD                                  KS 2177 : 2017 
                
 © KEBS 2017 — All rights reserved            
7 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 separa te Na and K lamps.  
 
5.7 A flame photometer (according to EAS 148 -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/I calibration solution and adjust burner height and acetylene flow to give maximum 
absorption. Spray the 0 mg/I solution and a djust 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 readou t 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 b oat. Record the 
mass of admixture sample in mg to the nearest 0 .1 mg (m 1). 
 
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 s ample thoroughly and weigh approximately 1 g recording the actual mass in mg to 0 .1 mg (m i). 
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 fo r (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 th e filtrate and washings in the volumetric flask.  KS 2177: 2017                                                                                                            
 
8                     © KEBS 2017 — All rights 
reserved  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 instructi ons 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/I 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. Refe r to the calibration 
graph and record the concentration of the sample solution in mg Na 2O/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/I calibration solution i.e. 
dilution D = 10. 
 
Mix thoroughly and repeat the procedure. Further dilutions may be required. Record mass m2 of Na 2O 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 m 3 of K2O in mg in 1 litre of solution.  
 
7.3. Results  
 
Calculate the Na 2O and K 2O content of the admixture from the following equations:  
 
 (1) 
 
 (2) 
Where  
m1 mass of admixture sample in mg  
 
m2 mass of Na 2O in mg  
 
m3 mass of K 2O in mg  
and 
D the dilution used if necessary.  
 
Calculate the total equivalent alkali content of the admixture from the following 
equation: Total Na 2O equivalent = Na 2O content + 0 .658 K 2O content % by 
mass  
Report the total Na 2O equivalent content in percen t 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 2O equivalen t. 
                          KS 2177: 
2017  
 
 
© KEBS 2017 — All rights reserved         
      9 
 
blank  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) Potassi um oxide content;  
 
i) Sodium oxide equivalent content.