KENYA STANDARD      DKS 2802-9:2019 
ICS  
  
 
 
  
 
  
 
 
 
  
 
  
Masonry units — Methods of test  
 
Part 9:  
Determination of moisture expansion of large 
horizontally perforated clay masonry units 
 
Public Review Draft April 2019 
 
 
 
  
 
  
 
  
 
  
 
    
 
  
 
  
 
  DKS 2802-9:2019  
ii  © KEBS 2019 — All rights reserved  
 
 
© KEBS 2019 First Edition, 2019 
TECHNICAL COMMITTEE REPRESENTATION 
 
The following organizations were represented on the Technical C ommittee:  
 
National Housing Corporation 
Kenya Clay Products Ltd 
Coast Clay Works Ltd 
Consumer Information Network 
University of Nairobi  
Kenya Industrial Research & Development Institute 
Architectural Association of Kenya 
M&O Consulting Engineers Kenya Association of Manufacturers, 
Kenya National Federation of Jua Kali Association 
Lake Basin Development Authority 
Kenya Bureau of Standards — Secretariat 
 
 
 
  
 
 
 
  
 
 
 
  
 
 
 
  
REVISION OF KENYA STANDARDS 
 
In order to keep abreast of progress in industry, Kenya Standar ds shall be regularly reviewed. Suggestions for 
improvements to published standards, addressed to the Managing Director, Kenya Bureau of Standards, are 
welcome. 
 
  
 KENYA STANDARD                                         DKS 2802-9:2019 
ICS  
© KEBS 2019 — All ri ghts reserved   iii © Kenya Bureau of Standards, 2017 
 
Copyright. Users are reminded that by virtue of Section 25 of the Copyright Act, Cap. 130 of 2001 of the Laws of Kenya, copyrig ht subsists 
in all Kenya Standards and except as provided under Section 25 of this Act, no Kenya Standard produced by Kenya Bureau of Stand ards 
may be reproduced, stored in a retrieval system in any form or transmitted by any means without prior permission in writing fro m the 
Managing Director.   DKS 2802-9:2019  
iv  © KEBS 2019 — All rights reserved Masonry units — Methods of test  
 
Part 9: 
 
Determination of moisture expansion of large 
horizontally perforated clay masonry units  
 
 
  
 
  
 
  
 
  
 
  
 
  
 
 
  
 
  
 
  
 
 
  
 
  
 
 
KENYA BUREAU OF S TANDARDS (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) 235 49, 22396  Tel.: (+254 051) 210553, 210555  
Fax: (+254 041) 229448   Fax: (+254 057) 21814 
 
Foreword KENYA STANDARD                                         DKS 2802-9:2019 
ICS  
© KEBS 2019 — All rights reserved   v  
This Kenya Standard was prepared by the Clay and Clay Products Technical Committee under the guidance 
of the Standards Projects Committ ee and in accordance with the procedures of the Kenya Bureau of 
Standards. 
 During the development of this standard, reference was made to the following documents: 
 
BS EN 772-19:2000 Methods of test for masonry units - Part 19: Determination of moisture expansion 
of large horizontally perforated clay masonry units.  
Acknowledgement is hereby made for the assistance received from  these sources. 
  
KENYA STANDARD        DKS 2802-9:2019 
 
 
© KEBS 2019 — All rights reserved   1  
Masonry units — Me thods of test  
 
Part 9:  
Determination of moisture expansion of large horizontally perfo rated clay 
masonry units 
 
1. Scope  
 
This Kenyan Standard specifies an accelerated method of determi ning the moisture expansion of large clay 
units with horizontal perforations that have one dimension equa l to or greater than 400 mm and shell 
thicknesses less than 12 mm.  
2. Normative references 
 The following referenced documents are indispensable for the ap plication of this document.  For dated 
references, only the edition cited applies.   For undated refer ences, the latest edition of the referenced 
document (including any amendments) applies.  
DKS 2801-1 Specification for masonry units - Part 1:  Clay maso nry units 
 
3. Principle 
 
This test measures the length change of test specimens caused b y subjecting them to boiling water for a 24 h 
period.  
4. Symbols 
 
Ii is the initial length an individual specimen after kiln retiri ng and cooling at ambient temperature, (mm) 
 
Rin       is the reading from the invar reference bar using the dir ect reading gauge, (mm) 
 
ls1         is the first deviation which is the difference between  the first reading from an individual specimen ( Rδ1) 
after kiln retiring and cooling to ambient temperature and the reading from the invar reference bar 
(Rin), in (mm). 
 
ls2  is the second deviation which is the difference between the s econd reading from an individual 
specimen ( Rδ2) after kiln retiring, cooling to ambient temperature and subse quent 3 h hold and the 
reading from the invar reference bar ( Rin), (mm) 
 
lm1       is the mean initial deviation of an individual specimen,  (mm) 
 
ls3        is the third deviation which is the difference between the third reading from an individual specimen 
(Rδ3) 1  h after cooling following boiling water treatment and the reading from the invar reference bar 
(Rin), (mm) 
 
ls4             is the fourth deviation which is the difference be tween the fourth reading from an individual specimen 
(Rδ4) 24 h after the third reading ( Rδ3) and the reading from the invar reference bar ( Rin), (mm) 
 
lm2             is the mean final deviation of a n individual specimen, (mm)   
2  © KEBS 2019 — All rights reserved  
 
es           is the moisture  expa nsion  of an individual  specim en,  (mm/m) 
 
em          is the mean value of m oisture  expansion,  (mm/m) 
 
5. Apparatus 
 
 
5.1. Reference bars  of nickel steel (invar) of the approximate length of the test specimens. 
 
5.2. Kiln  capable of maintaining a rate of rise of temperature of approx imately   50 °C/h and a temperature 
of 600 °C ± 15 °C. 
 
5.3. Suitable type of measuring frame  fitted with a dial gauge, a transducer or similar device, with  an 
accuracy of at least 0,01 mm  (see example in Figure 1). 
 
5.4. Vernier callipers or other suitable apparatus for linear measurement to the nearest 0,1 mm. 
 
5.5. Special measurement reference pads and adhesive , if necessary. 
 
5.6. Apparatus for maintaining the test specimens in boiling wa ter for 24 h. 
 
5.7. Desiccator  capable of holding all the specimens. 
 
 
6. Sampling 
 
The method of sampling shall be in accordance with DKS 2801-1. The minimum  number  of specimens  shall 
be six, but a larger number  may be specified  in the product  specification  in which case that larger number  
shall be used. 
 
7. Procedure 
 
7.1. Preparation 
 Cut a specimen out of a shell from each masonry unit parallel t o the perforations.   The length shall be as great 
as possible between 150 mm to 250 mm, depending on the referenc e bars (5.1). The minimum width shall be 
40 mm. Prepare the ends of the specimens as necessary so that t he measuring device bears onto flat surfaces 
perpendicular to the axis of the specimen. 
 
Note:  Special  end preparation   may have to be carried  out on  the specimens  before  being measured,  e.g. 
special  adhesive  measurement  reference  pads ( 5 .5) or depr essions  cut in ends of specimen  as 
appropriate.  
  
7.2. Retiring 
 
If the specimens have been wetted during preparation then store  them for 24 h at ambient temperature. 
 
Retire the specimens in a kiln (5.2), maintaining a temperature  rise of 50 °C/h until a temperature of 600° C ± 
15 °C has been reached. Maintain this temperature for 4 h.  
Allow the specimens to cool inside the kiln. When the temperatu re has fallen to 70 °C remove the specimens 
and keep them in a desiccator (5. 7 ) at ambient temperature for  at least 20 h. 
 
 
  
7.3. Initial measurement DKS 2802-9:2019  
© KEBS 2019 — All rights reserved   3  
7.3.1. Initial  measurement of total length ( Ii) 
 
Determine and record the length ( /i) of each specimen to the nearest 0,1 mm using vernier calliper s (5.4) or 
other suitable apparatus. Choose the invar reference bar accord ingly. 
 
7.3.2. Measurement of first and second  deviations  ( ls1 and ls2 )  and mean initial deviations 
(lm1) 
 
The readings required by this sub-clause are made using the mea suring frame ( 5 .3) and to the nearest 0,01 
mm.  
Take and record the reading of the invar reference bar (
Rin). 
 
Take and record the first reading of each specimen after kiln r efiring and cooling to ambient temperature ( Rδ1). 
Calculate and record, for each specimen, the first deviation ( ls1), i.e. the difference between  Rδ1 and Rin to 
the nearest 0,01 mm. 
 
Take and record the second reading of each specimen after kiln refiring, cooling to ambient temperature and 
subsequent 3 h hold ( Rδ2).   Calculate and record, for each specimen, the second deviat ion (ls2), i.e. the 
difference between Rδ2 and Rin to the nearest 0,01 mm. Examples of deviations are illustrated  in Figure 2. 
 
For each specimen, record the initial deviation ( lm1) as the mean of ( /s1)   and ( /s2) to the nearest 
0,01 mm. 
 
7.4. Boiling  water  treatment 
 
Immerse the specimens in boiling water (5.6) for 24 h. The test  specimens shall be supported clear of the base 
of the tank and shall not be in contact with the sides. 
 
Remove the test specimens and allow them to cool at room temper ature.  
  
7.5. Measurement  of third  and fourth  deviations (
/s3  and ls4)   and mean final deviations ( lm2) 
 
The readings required by this sub clause are made using the mea suring frame and to the nearest 
0,01 mm. 
 
Take and record the reading of the invar reference bar ( Rin). 
 
Take and record the third reading of each specimen 1  h after c ooling  following  boiling  water treatment  ( Rδ3). 
Calculate and record, for each specimen, the third deviation ( /s3), i.e.  the difference between  Rδ3  and Rin to 
the nearest  0,01 mm. 
 Take and record the fourth reading of each specimen ( R
δ4) 24 h after the third reading ( Rδ3). Calculate and 
record, for each specimen, the fourth deviation ( ls4),   i.e. the difference between Rδ4 and Rin to the nearest 
0,01 mm. 
 
For each specimen, record the final deviation ( /m2) as the mean of ( /s3) and ( /s4) to the nearest 
0,01 mm. 
  
 
  
 
 
8. Expression of results  
4  © KEBS 2019 — All rights reserved  
For each specimen  calculate  the moisture  expansion  due to t he boiling  water treatment   (es) to the nearest  
0, 1  mm/m  as follows;   
                
 
From the individual values (
es) calculate the mean value of the moisture expansion ( em) to the nearest 
 0,1 mm/m. 
 
9. Test report 
 The test report shall contain the following information: 
 
a) the number,  title and date of issue of this Kenyan  Standar d, 
b) the name of the organization  that carried out the sampling and the method used; 
c) the date of testing; 
d) the type, origin and designation  of the masonry  unit by re ference  to DKS 2801-1; 
e) the number of specimens  in the sample; f) the date of delivery of the sp ecimens to the testing laborat ory;  
g) the moisture expansion
 es for each specimen expressed i n mm/m, to the near est 0,1 mm/m; 
h) the mean value em of moisture expansion expressed in mm/m, to the nearest 0,1 mm /m; 
i) remarks (if any). 
 
DKS 2802-9:2019  
© KEBS 2019 — All rights reserved   5  
 
6  © KEBS 2019 — All rights reserved