ICS 91.080.30   
 
Reference number  
DRS  211-7: 2010 
© RSB 2021  
  
 RWANDA 
STANDARD  DRS  
211-7  
 
First edition  
2010 -03-18 
Reaffirmed yyyy-mm-dd 
Mortar for masonry — Test methods  —  
Part 7: Determination of water absorption 
coefficient due to capillary action of 
hardened mortar  
   
DRS 211-7: 2010 
©RSB 2021  - All rights reserved                  ii 
 In order to match with technological development and to keep continuous progress in industries, 
standards are subject to periodic review. Users shall ascertain that they are in possession of the latest 
edition 
 
 
 
 
 
 
 
 
© RSB 2021  
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized 
in any form or by any means, electronic or mechanical, including photocopying and microfilm, without 
prior written permission from R SB. 
Requests for permission to reproduce this document should be addressed to : 
Rwanda Standards  Board  
P.O Box 7099 Kigali -Rwanda  
KK 15 Rd, 49  
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Toll Free: 3250  
E-mail: info@rsb.gov.rw  
Website: www.rsb.gov.rw  
ePortal: www.portal.rsb.gov.rw   DRS 211-7: 2010 
iii                ©RSB 2021  - All rights reserved  
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ ...................  iv 
1 Scope  ................................ ................................ ................................ ................................ .............  1 
2 Normative references  ................................ ................................ ................................ ...................  1 
3 Terms and definitions  ................................ ................................ ................................ ..................  1 
4 Principle  ................................ ................................ ................................ ................................ ........  1 
5 Apparatus  ................................ ................................ ................................ ................................ ...... 1 
6 Materials  ................................ ................................ ................................ ................................ ........  2 
7 Sampling and prepara tion and storage of test specimens  ................................ ......................  2 
7.1 General  ................................ ................................ ................................ ................................ ..........  2 
7.2 Laboratory prepared mortars  ................................ ................................ ................................ ...... 2 
7.3 Mortars, other than laboratory prepared mortars  ................................ ................................ ..... 2 
7.4 Preparation and curing of test specimens ................................ ................................ .................  3 
7.5 Drying  ................................ ................................ ................................ ................................ ............  3 
8 Procedure  ................................ ................................ ................................ ................................ ...... 3 
9 Calculation and expression of results  ................................ ................................ .......................  5 
10 Test report  ................................ ................................ ................................ ................................ ..... 6 
 DRS 211-7: 2010 
©RSB 2021  - All rights reserved                  iv 
 Foreword  
Rwanda Standard s are prepared  by Technical Committees and approved by Rwanda Standards Board (RSB) 
Board  of Directors in  accordance with the procedures of RSB, in compliance with Annex 3 of the WTO/TBT 
agreement on the preparation, adoption and application of standards.  
The main task of technical committees is to prepare national standards.  Final Draft Rwanda S tandards adop ted 
by Technical committ ees are ratified  by me mbers of RSB Board of Director s for publication and gazettment as 
Rwanda Standards.  
DRS 211-7 was prepared by Technical Committee RSB/TC 009, Civil engineering and building materials . 
In the preparation of this standard, reference was made to the following standard s: 
1) BS EN 998 -1: 2016, Specification for mortar for masonry — Part 1: Rendering and plastering mortar  
2) BS EN 998 -2: 2016, Specification for mortar for masonry — Masonry mortar  BS EN 1 015-2:1999+A1: 2006, 
Methods of test for mortar for masonry – Part 2: Bulk sampling of mortars and preparation of test mortars  
3) BS EN 1015 -3: 1999, Methods of test for mortar for masonry – Part 3: Determination of consistence of fresh 
mortar (by flow table )  
4) BS EN 1015 -18:2002 , Methods of test for mortar for masonry - Determination of water absorption coefficient 
due to capillary action of hardened mortar  
5) BS EN 1015 -11:2019 , Methods of test for mortar for masonry – Part 11: Determination of flexural and 
compressive strength of hardened mortar   
The assistance de rived from the above source is hereby acknowledged with thanks.  
DRS 211 consists of the following parts, under the general title Mortar for masonry  —Test methods : 
⎯ Part 1: Determination of particle size distribution (by sieve analysis)  
⎯ Part 2: Bulk sampling of mortars and preparation of test mortars  
⎯ Part 3: Determination of consistence of fresh mortar (by flow table)  
⎯ Part 4: Determination of consistence of fresh m ortar (by plunger penetration)  
⎯ Part 5: Determination of flexural and compressive strength of hardened mortar  
⎯ Part 6: Determination of adhesive strength of hardened rendering and plastering mortars on substrates  
⎯ Part 7: Determination of water absorption c oefficient due to capillary action of hardened mortar  DRS 211-7: 2010 
v                ©RSB 2021  - All rights reserved  
 Committee membership  
The following organizations were represented on the Technical Committee on and civil engineering and b uilding 
materials (RSB/TC 009)  in the preparation of this standard.  
Advanced C onstruction Technology Services (ACTS) - Rwanda  
CIMERWA   
City of Kigali   
Green Pact Africa   
Rwanda Inspectorate, Competition and Consumer Protection Authority (RICA)  
RTDA   
Standard Geotechnical Engineering and Construction Ltd (STAGECO Ltd)  
SJEC Ltd  
UR-CST  
Rwanda  Standards Board  (RSB) – Secretariat  
 DRS 211-7: 2010  
1                ©RSB 2021  - All rights reserved  
 Mortar for masonry — Test methods  — Part 7: Determination of water 
absorption coefficient due to capillary action of hardened mortar  
1 Scope  
This Draft Rwanda Standard provides  a method for determining the water absorption coefficient due to capillary 
action of hardened mortars containing mineral binders and normal as well as light weight aggregates .  
2 Normative references  
The following documents are referred to in the text in su ch a way that some or all of  their content constitutes 
requirements of this document.  For dated references, only the edition  cited applies. For undated references, the 
latest edition of the referenced document (including any amendments) applies.  
RS 108, Mortar for masonry — Specification   
DRS 211-1, Mortar for masonry — Test methods  — Part 1: Determination of particle size  distribution (by 
sieve analysis)   
DRS 211-2, Mortar for masonry — Test methods  — Part 2: Bulk sampling of mortars and preparation of te st 
mortars   
DRS 211-3, Mortar for masonry — Test methods  — Part 3: Determination of consistence of fresh mortar (blow 
table)   
DRS  211-5, Mortar for masonry — Test methods  — Part 5: Determination of flexural and compressive 
strength of hardened mortar.  
3 Terms and definitions  
No terms and definitions are listed in this document  
4 Principle  
The water absorption coefficient due to capillary action is measured using mortar prism s pecimens under 
prescribed conditions at atmospheric pressure. After drying to constant mass, one face of the specimen is 
immersed in 5 mm - 10 mm of water for a specific period of time and the increase in mass determined.  
5 Apparatus  
5.1 Tray , of minimum d epth of 20 mm and of plan area large enough to contain the specimens to be immersed 
and fitted with a means of maintaining a constant water level.   
5.2 Four support pads or similar per specimen , to store the specimen, with a minimum contact area, clear 
of the base tray and with the specified depth of immersion.   
©RSB 2021  - All rights reserved                  2 
 5.3  Stopwatch , graduated in seconds.  
5.4  Weighing instrument , with an accuracy of 0.1 % of the total, dry mass of the test specimen.  
5.5  Ventilated oven , capable of maintaining a temperature of  60 °C + 5 °C.  
5.6  Trowel or palette knife.  
5.7 Absorbent filter papers,  with a specific mass of 200 g/m2 + 20 g/m2 and water absorption capacity of 
160 g/m2 + 20 g/m2; twelve sheets each with a size of approximately 150 mm x 175 mm.  
5.8  Conditioning chamber or room , capable of maintaining a relative humidity of 95 % ± 5 %  
5.9 Metal mould and other ancillary apparatus , to produce 160 mm x 40 mm x 40 mm prism specimens 
as described in RS 211 -5.  
6 Materials  
6.1 Demineralized or distilled wa ter  
6.2  Sealing material, e.g. paraffin wax or synthetic reactive resin with a melting point above 60 °C.   
7 Sampling and preparation and storage of test specimens  
7.1 General  
The fresh mortar for this test shall have a minimum volume of 1.5 L or at least 1.5 times the quantity 
needed to perform the test, whichever is the greater, and shall either be obtained by reduction of the 
bulk test sample (see RS 211 -2) using a sample div ider or by quartering or by preparation from water 
and the other constituents in the laboratory. Three test specimens shall be prepared from the sample of 
mortar.  
7.2 Laboratory prepared mortars  
7.2.1 The length of mixing period shall be measured from the mo ment all the constituents are introduced into 
the mixer.  
7.2.2 The mortar shall be brought to a defined flow value as specified in RS 211 -2 determined in accordance 
with RS 211 -3 and reported.  
7.3 Mortars, other than laboratory prepared mortars  
7.3.1 Ready to use mortars (plant -made wet mortars which are retarded), and pre -batched air -lime/sand wet 
mortars when not gauged with hydraulic binders, shall be used for specimen preparation within their specified 
workable life.  DRS 211-7: 2010  
3                ©RSB 2021  - All rights reserved  
 7.3.2 Before testing, the batch shal l be gently stirred by hand using a trowel or palette knife (see 5.6) for 5 s 
to 10 s to counteract any false setting etc., but without any additional mixing of the batch.  
7.3.3 The flow value of the mortar in the bulk test sample shall be determined in a ccordance with  RS 211 -3 
and reported.  
7.4 Preparation and curing of test specimens  
Prepare three test specimen prisms with dimensions 160 mm x 40 x 40 mm according to RS 211 -5. Line 
the base of the metal mould with filter paper and fill with mortar and strik e off the surface flush with the 
top of the mould. Place a layer of filter paper on the mortar surface. Cure the test specimens under the 
conditions described in Table 1. At the end of the curing period, demould the specimens. Seal the four 
long faces of t he specimens using the specified sealing material, then beak them into two halves.  
Table 1 — Curing of test specimens  
Type of mortar  Curing time at a temperature of 20 °C + 2°C in days  
95 % + 5 % RH (relative humidity)  65 % + 5 % RH  
in the moulda)  with the mould 
removed  with the mould 
removed  
Lime mortars  5  2  21  
Lime/cement mortars in which the 
amount of lime is greater than 50 % of 
the total binder weight  5  2  21  
Cement and other lime/cement mortar  2  5  21  
Mortars with other hydraulic binders  2  5  21  
Retarded mortars  5  2  21  
a) 
  In some cases an extended period of storage in the mould may be necessary.  
7.5 Drying  
7.5.1 Dry the test specimens to constant mass in a ventilated oven at a temperature of 60 °C + 5 °C. Constant 
mass is reached, if during the drying process in two subsequent weighings with a 24 -h interval, the loss in mass 
between the two determinations is not m ore than 0.2 % of the total mass.  
7.5.2  For renovation mortars only, record the dry mass of each specimen (M3).  
8 Procedure  
8.1 Place the specimens in the tray (4.1), with the broken faces of the prisms downwards, supported clear of 
the base of the tray on the four support pads (4.2), immersed in water ( 6.1) to a depth of 5 mm - 10 mm for the 
duration of the test (see Figure 1). To ensure full immersion of rough surface textured specimens avoiding 
trapping air bubbles beneath them, immerse them in a sloping attitude.   
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 8.2  Activate the timing device. Maintain the water level constant throughout the test.  
8.3  Cover the tray to avoid evaporation from the wet test specimens.  
8.4 If visible wetting occurs on the free surface of the test specimens, stop  the test. Break the specimens to 
ensure that they are fully saturated. If they are saturated then weigh the two pieces together. If not fully 
saturated, repeat the test with a new specimen.  
NOTE  If, when the specimen is broken, it is not saturated across  the whole area, it can be that the sealing of the long 
faces was inadequate. Therefore, special attention should be paid to this aspect of preparation of any replacement 
specimens.  
8.5 For mortars other than renovation mortars; remove the specimens from the tray after 10 min, wipe off 
rapidly surface water with a dampened cloth, weigh the specimen (M1) and replace them immediately into the 
tray. Repeat the same procedure after 90 min and weigh (M2).  
8.6 For renovation mortars only; Remove the specimens f rom the tray after 24 h and weigh them (M3). 
Immediately afterwards, split each specimen along its length to give approximately pieces of dimension 80 mm 
x 40 mm x 20 mm. Measure the height of water penetration in the centre of the specimen parallel to the  80 mm 
dimension with an accuracy of 1 mm.  
Dimensions in millimetres  
  
Figure 1 — Render specimens  
Key  
1 Prism specimen  
2 Broken end face of prim  
3 Water surface  
DRS 211-7: 2010  
5                ©RSB 2021  - All rights reserved  
 A Approximately  
B Immersion 5 mm - 10 mm  
NOTE  10 mm are used if surface is heavily textured.   
9 Calculation and expression of results  
9.1 For other than renovation mortars the coefficient of water absorption is by definition equal to the slope of 
the straight line linking the representative points of the measurements carried out at 10 min and 90 min.  
9.2  Calculate it on the basis of the following formula:  
𝐶=0.1(𝑀1−𝑀2)𝑘𝑔 (𝑚2𝑚𝑖𝑛0.5)  
where:  
𝑀1 is the mass of the specimen after soaking for 10 min, (g);  
𝑀2 is the mass of the specimen after soaking for 90 min, (g); and  
C is the coefficient of water absorption for an individual mortar specimen, (kg/ m2.min0.5) (for mortars other 
than renovation mortars ) or (kg/m2) (for renovation mortars).  
9.3 For renovation mortar only, water absorption is measured in kg/m2 after 24 h using the following formula:  
 𝐶=0.625  (𝑀3−𝑀0)𝐾𝑔/𝑚2 
where  
𝐶 is the coefficient of water absorption for an indi vidual mortar specimen, (kg/ m2.min0.5) (for mortars other 
than renovation mortars ) or (kg/m2) (for renovation mortars);  
𝑀3 is (for renovation mortars) the mass of the specimen after soaking for 24 h, (g); and  
𝑀0 is (for renovation mortars) the dry ma ss of the specimen, (g).  
NOTE  Water penetration depth is determined in mm.  
9.4 Calculate individual values of coefficient of water absorption (C) to the nearest 0.05 kg/ m2.min0.5) or 
nearest 0.05 kg/m2 as relevant.  
9.5 Calculate the mean value of coefficient of water absorption (C m) from the individual values to the nearest 
0.1 kg/ (m2. min 05) or nearest 0.05 kg/m2 as relevant.  
NOTE C m is the mean coefficient of water absorption of the sample of mortar due to capillary action, (kg/ (m2. min0.5)) (for 
mortars other than renovation mortars) or (kg/m2) (for renovation mortars).   
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 10 Test report  
The test report shall contain the following information:  
a) the place, date and time of taking the bulk test sample;  
b) the method used for taking the bulk test samp le (if known) and the name of the organization  that 
took it;  
c) the type, origin and designation of the mortar by reference to of RS 108;   
d) preparation (mixing, casting) and curing conditions;  
e) the date and time of preparation of the specimens for test;  
f) the flow value of the test mortar determined in accordance with RS 211 -2;  
g) the date and time of testing;  
h) Individual values of coefficient of water absorption due to capillary action (c) stated to the nearest 
0.05 kg/(m2.min0.5) or nearest 0.05 kg/m2 as re levant, and, for other than renovation mortars, the 
length of time of immersion of each specimen;  
i) the mean coefficient of water absorption due to capillary action (cm) stated to the nearest 0.1 
kg/(m2.Min0.5) or nearest 0.05 kg/m2 as relevant; and  
j) remark s, if any.  
 NOTE 1  The sample taken from the bulk supply that is to be used for all of the tests in RS 211.  
 NOTE  2  This information is contained on the certificate of sampling (see RS 211 -1).  
 
 
 DRS 211-7: 2010  
 
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