KENYA STANDARD      DKS 2802-10:2019 
ICS  
  
 
 
  
 
  
 
 
 
  
 
  
Masonry units — Methods of test  
 
Part 10 : 
 
Determination of flatness of faces of aggregate 
concrete, manufactured stone and natural stone 
masonry units  
 
  
 
 
  
 
  
 
  
 
  
 
  
 
 
  
 
 
  
 
 
© KEBS 2019 First Edition, 2019 DKS 2802-10:2019  
ii  © KEBS 2019 — All rights reserved 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 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.  KENYA STANDARD                                       DKS 2802-10:2019 
ICS  
© KEBS 2019 — All ri ghts reserved   iii Masonry units — Methods of test  
 
Part 10:  Determination of flatness of f aces of aggregate concrete, 
manufactured stone and natural stone 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  
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Fax: (+254 041) 229448   Fax: (+254 057) 21814 
 DKS 2802-10:2019  
iv  © KEBS 2019 — All rights reserved Foreword 
 
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 772-20:2000 Methods of test for masonry units - Part 20: Determination of flatness of faces of 
aggregate concrete, manufactured stone and natural stone masonr y units 
 
Acknowledgement is hereby made for the assistance received from  these sources. 
  
KENYA STANDARD        DKS 2802-10:2019 
 
 
© KEBS 2019 — All rights reserved   1  
Masonry units — Me thods of test  
 
Part 10:  
Determination of flatness of f aces of aggregate concrete, manuf actured 
stone and natural sto ne masonry units 
 
1. Scope  
 
This Kenyan Standard specifies a method for determining   the f latness of faces of aggregate concrete, 
manufactured   stone and natural stone masonry units. 
 
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. 
 prEN  771-3         Specification  for masonry  units  -  Part  3: Aggregate  concrete  masonry  units  (dense  and 
lightweight  aggregates) 
 prEN 771-5         Specification for masonry  units -  Part 5: Manufactured   stone masonry  units  
 
prEN 771-6         Specification for masonry  units -Part  6: N atural  stone masonry  units 
  
3. Apparatus 
 
3.1. Graduated   straight    edge   which  is  longer  than  the  diagonals   of the  long  faces   of the  unit  
being tested. 
 
3.2. Set of feeler gauges  capable of measuring with an accuracy to 0,05 mm. 
 
4. Preparation   of specimens 
 
4.1. Sampling 
 
The method of sampling shall be stated in the test report. The minimum number of specimens shall be six, but 
a larger minimum number may be specified in the product specifi cation, in which case that larger number shall 
be used.  
4.2. Surface treatment 
 
Remove any superfluous material adhering to the unit as a resul t of the manufacturing process before 
measuring.  
 
5. Procedure 
 
Ensure that the masonry unit is positioned in a stable manner p rior to measurement. For each face specified 
as flat measure the length of the two diagonals with the gradua ted straight edge (3 .1) to the nearest 0,5 mm. 
Place the straight edge across each diagonal in turn and use th e feeler gauge (3.2) to measure the distance 
from the face of the masonry unit to the straight edge. Where t he face of the masonry unit is concave measure  
2  © KEBS 2019 — All rights reserved the greatest distance from the face of the straight edge to the  nearest 0,05 mm. Where the face of the masonry 
unit is convex place the straight edge on it such that the grea test distances to the face on either side of the 
point of contact are approximately equal. Measure them both to the nearest 0,05 mm. 
 
6. Calculation and expression of results 
 
6.1. Calculation of results 
 
Calculate the mean length of the diagonal. In the case of conca ve faces calculate the mean deviation from 
flatness as the mean of the maximum distances of the face of th e masonry unit from the straight edge on each 
diagonal. In the case of convex faces calculate the mean of the  maximum distances of the face of the masonry 
unit from the straight edge for each diagonal and then calculat e the mean deviation from flatness as the mean 
of these two results. 
 
6.2. Expression of results 
 
Express the mean length of the diagonal to the nearest mm.  Exp ress the mean maximum deviation from 
flatness to the nearest 0,1 mm. 
 
7. Test report 
 The test report shall contain the following information: 
 
a) the number, title and date of issue of this Kenyan Standard;  
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  desi gnation   of  the  masonry  unit  by  reference   to prEN 771-3 , prEN771-5 
or prEN771-6; 
e)  the number of specimens in the sample; 
f) the date of receipt of the sp ecimens  in the testing laborat ory; 
g) the length of the individual diagonals of each face and the mean length of the diagonals to the nearest 
millimetre;  
h) the maximum  distance  from the face of the masonry  unit to  the straight  edge for each diagonal and 
the mean  deviation  to the nearest  0, 1 mm; 
i) whether  the face of the masonry  unit is concave  or convex   or any other configuration; 
j) remarks,  if any.  
.