KENYA STANDARD      DKS 2802-6:2019 
ICS  
  
 
 
  
 
  
 
 
 
  
 
  
Masonry units — Methods of test  
 
Part 6:  
Determination of water absorption of aggregate 
concrete, autoclaved aerated concrete, 
manufactured stone and natural stone masonry 
units due to capillary action and the initial rate of 
water absorption of clay masonry units 
 
 
 
  
 
   
 
  
 
   
 
  
 
  
 
© KEBS 2019 First Edition, 2019 
 DKS 2802-6:2019  
ii  © KEBS 2019 — All rights reserved  
  KENYA STANDARD                                         DKS 2802-6:2019 
ICS  
© KEBS 2019 — All ri ghts reserved   iii 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.  
  DKS 2802-6:2019  
iv  © KEBS 2019 — All rights reserved  
 
 
  
 
  
 
 
  
 
Masonry units — Methods of test  
 
Part 6: 
 
Determination of water absorption of aggregate concrete, autoclaved aerated concrete, manufactured 
stone and natural stone masonry units due to capillary 
action and the initial rate of water absorption of 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  
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Fax: (+254 041) 229448   Fax: (+254 057) 21814 
 KENYA STANDARD                                         DKS 2802-6:2019 
ICS  
© KEBS 2019 — All rights reserved   v Foreword 
 
This Kenya Standard was prepared by the Clay and Clay Products Technical Committee under the guidance 
of the Standards Projects Committe e 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 772-11:2011 Methods of test for masonry units - Part 1: D etermination of water absorption of 
aggregate concrete, autoclaved aerated concrete, manufactured s tone and natural stone masonry 
units due to capillary action a nd the initial rate of water abs orption of clay masonry units. 
 
Acknowledgement is hereby made for the assistance received from  these sources. 
  
KENYA STANDARD        DKS 2802-6:2019 
 
 
© KEBS 2019 — All rights reserved   1  
Masonry units — Me thods of test  
 
Part 6:  
Determination of water absorptio n of aggregate concrete, autocl aved 
aerated concrete, manufactured sto ne and natural stone masonry units 
due to capillary action and the initial rate of water absorptio n of clay 
masonry units 
 
1. Scope  
 
This Kenyan Standard specifies a method of determining the wate r absorption coefficient due to capillary action 
for aggregate concrete, autoclaved aerated concrete, natural st one and manufactured stone masonry units 
and the initial rate of water ab sorption for clay 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 refere nces, the latest edition of the referenced 
document (including any amendments) applies.  DKS 2801 -1, Specification for masonry units -   Part 1: Clay m asonry units 
 
EN 771-2, Specification for masonry units -   Part 2: Calcium s ilicate masonry units 
 EN 771-3, Specification for masonry units -    Part 3: Aggregat e concrete masonry units (Dense and light• 
Weight aggregates) 
 EN 771-4, Specification for masonry units -   Part 4: Autoclave d aerated concrete masonry units 
 
EN 771-5, Specification for masonry units -   Part 5: Manufactu red stone masonry units 
 
EN 771-6, Specification for masonry units -   Part 6: Natural s tone masonry units 
 DKS 2802 - 8, Methods of test fo r masonry units-    Part 16: De termination of dimensions 
 
3. Principle 
 
After drying to constant mass, a face of the masonry unit is im mersed in water for a specific period of time and 
the increase in mass is determined. 
 
In the case of clay masonry units the initial rate of absorptio n of the bed face is measured. In the case of 
aggregate concrete, autoclaved aerated concrete, natural stone and manufactured stone masonry units the 
water absorption of face of the unit to be exposed is measured,  as described in the relevant product standard 
 
4. Symbols 
 
Mdry,s         is the mass of the specimen after drying, (g);  
 
MS0,S               is the mass of the specimen in grams after soaking for time t, (g);  
2  © KEBS 2019 — All rights reserved  
As             is the gross area of the face of the specimen immersed in water , (mm2): 
tS0               is the time of soaking, (s);  
 
NOTE         Specified in the relevant part of DKS 2801. 
 
Cw,s               is the coefficient of water absorption due to capillary action for aggregate concrete autoclaved 
aerated concrete, natural stone and manufactured stone masonry units; 
 
Cwi,s                 is the initial rate of water absorption for clay masonry units,  [kg/(m2 x min)].   
 
 
5. Apparatus 
 
5.1. Large tray  of minimum depth of 20 mm and of plan area larger than the fac e of the masonry unit to 
be immersed fitted with a means of maintaining constant water l evel. 
 
5.2. Supporting device  of 400 mm2 maximum plan area to keep each specimen clear of the base of t he 
tray. 
 
5.3. Stopwatch  graduated in seconds. 
 
5.4. Ventilated  oven   capable of  maintaining a temperature of  70 °C ±  5 °C for  aggregate concrete, 
autoclaved aerated concrete, natural  stone and manufactured st one units or 105 °C ± 5 °C for clay 
units. 
 
5.5. Weighing instrument  capable of weighing the specimens to an accuracy of 0,1 % of t heir mass 
when dry. 
 
 
 
6. Preparation of specimens 
 
 
6.1. Sampling 
 
The method of sampling shall be in accordance with the relevant  part of DKS 2801. The minimum number of 
specimens shall be six, but a larger minimum number may be spec ified in the product specification, in which 
case that larger number shall be used. 
 
 
6.2. Drying 
 
Dry the test specimens to constant mass Mdry,s in a ventilated oven (5.4) at a te mperature of 70 °C ± 5 °C for  
aggregate concrete, autoclaved aerated concrete, natural stone and manufactured stone masonry units or 
105 °C ± 5 °C for clay masonry units. Constant mass is reached,  if during the drying process in two subsequent 
Weighing’s with a 24 h interval, the loss in mass between the t wo determinations is not more than 0,1 % of the 
total mass. 
 
 
7. Test procedure 
 
Allow the specimens to cool at room temperature. When cool, mea sure the dimensions of the faces to be 
immersed in accordance with the principle incorporated in DKS 2 802-8 and calculate the gross area A5.     
Place the specimens with their faces (bed faces in the case of clay units) supported on a supporting device 
(5.2) so that they are clear of the base of the tray (5.1) and immerse in water to a depth of 5 mm ± 1    mm for 
the duration of the test. In the case of masonry units with an extremely irregular face, raise the water level in DKS 2802-6:2019  
© KEBS 2019 — All rights reserved   3 such a way that the complete surface just makes contact with th e water surface. For natural stone masonry 
units record whether the test face is parallel or perpendicular  to the bedding planes. 
 Activate the timing device. Maintain the water level constant t hroughout the test.  For aggregate concrete, 
autoclaved aerated concrete, natural stone and manufactured sto ne units, cover the tank to avoid evaporation 
from the wet specimens.  
After the immersion time (t50)   specified in DKS 2801-1, EN 77 1-3, EN 771-4, EN 771-5 or EN 771-6 remove 
the specimens, wipe off surface water and weigh them ( M
S0,S). 
 For natural stone masonry units, remove the specimens from the water at regular intervals, wipe off the water, 
weigh them, then re-immerse them. Continue this procedure until  no further increase in mass is observed. For 
some clay masonry units the initial rate of water absorption ca n differ for the two bed faces, in which case it 
will be necessary to measure on both faces.  
 
8. Calculation and expression of results 
 
 
8.1. Coefficient of water absorption due to capillary action of  aggregate concrete and 
manufactured stone units  
 
Calculate the coefficient of water absorption of the masonry un its due to capillary action to the nearest 
0, 1 g/m2.s using the following formula: 
 
 
 
 
8.2. Coefficient of water absorption due to capillary action of  autoclaved aerated concrete and 
natural stone masonry units 
 
Calculate the coefficient of water absorption of the masonry un its due to capillary action of each specimen to 
the nearest 1g /(m2   x S0ꞏ5)    using the following formula: 
 
 
In the case of natural stone masonry units, plot a graph of            against the square root of  
 
 the time immersed, in seconds. Calculate C
w,s  as the gradient over the initial linear portion of the graph. 
 
 
8.3. Initial rate of water absorption of clay masonry units 
 
Calculate the initial rate of water absorption of each clay mas onry unit to the nearest 0, 1 kg/ (m2 x min) using 
the following formula: 
  
 
 
Where t = 1 min.  
 
4  © KEBS 2019 — All rights reserved  
9. Evaluation of results 
 
For aggregate concrete and manufactured stone masonry units cal culate the mean of the coefficients of water 
absorption due to capillary act ion to the nearest 0, 1 g/(m2   x s). 
 
For autoclaved aerated concrete and natural stone masonry units  calculate the mean of the coefficients of 
water absorption due to capillary  action to the nearest 1   g/( m2  x s0ꞏ5). 
 
For  clay  masonry  units  calculate  the  mean  of  the  initi al  rates  of  water  absorption  to  the  nearest 
0, 1 kg/(m2 x min).  
 
10. Test report 
 The test report shall contain the following information: 
 
a) number, title and date of issue of this Kenyan Standard; 
b) name of the organization tha t carried out the sampling and t he method used; 
c) date of testing (in the case of aggregate concrete, autoclav ed aerated concrete and manufactured 
stone masonry units only); 
d) description of the specimens to the relevant  part of DKS 28 01; 
e) number of specimens in the sample and whether these are whol e units or representative portions 
thereof; 
f) date of receipt of the specimens in the testing laboratory; 
g) for aggregate concrete and manufactured stone masonry units,   the individual values of water 
absorption coefficient due to capillary  action to  the  neares t 0, 1    g(m2   x  s) for  each  unit, the  
length of time  of immersion and the mean water absorption coef ficient due to capillary action to the 
nearest 0, 1   g(m2  x s); 
h) for  autoclaved  aerated  concrete  and  natural  stone  mas onry  units,  the  individual  values  of  water 
absorption coefficient due to ca pillary action to the nearest 1    g/(m2 x s 0'5)    for each unit, the length 
of time of  immersion  and  the  mean  water  absorption  coeff icient  due  to  capillary  action  to  the  
nearest 1 g/(m
2  x s 0,5).     For natural stone masonry units state whether the test f ace was parallel or 
perpendicular to the bedding planes; 
i) for  clay  masonry  units,  the  individual  values  of  ini tial   rate  of  water  absorption  to  the   nearest 
0, 1 kg/(m2 x min), and the mean of the initial rates of water absorption to the nearest 0,1kg/(m2 x min); 
j) remarks,  if any.  
 
 
  DKS 2802-6:2019  
© KEBS 2019 — All rights reserved   5 Annex A 
(informative) 
 
The coefficient of water absorpti on of aggregate concrete and m anufactured stone masonry units is now 
calculated to a new formula given in 8.1.    In the previous ed ition, the formula now given in 8.2 had been 
applied to these types of units also.