ICS 91.100 .10 
 
Reference number  
RS nnn-n: yyyy 
© RSB yyyy 
  
 RWANDA 
STANDARD  DRS 
426-1  
 
1st edition  
yyyy-mm-dd 
 
Masonry Cement  — 
Part 1 : Composition, specifications and  
Conformity criteria  
 
 DRS 426-1: 2020 
©RSB yyyy - 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 yyyy 
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized 
in any form or by any means, electro nic 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  
Tel. +250 78830349 2 
Toll Free: 3250  
E-mail: info@rsb.gov.rw  
Website: www.rsb.gov.rw  
ePortal: www.portal.rsb.gov.rw   DRS 426-1: 2020 
iii                ©RSB yyyy - All rights reserved  
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ ............................  iv 
1 Scope  ................................ ................................ ................................ ................................ ......................  1 
2 Normative references  ................................ ................................ ................................ ............................  1 
3 Terms and definitions  ................................ ................................ ................................ ...........................  1 
4 Symbols and abbreviated terms  ................................ ................................ ................................ ..........  3 
5 Requirements  ................................ ................................ ................................ ................................ .........  3 
5.1 General  ................................ ................................ ................................ ................................ ...................  3 
5.2 Constituents and composition  ................................ ................................ ................................ .............  4 
5.3 Physical and mechanical requirements  ................................ ................................ ..............................  5 
5.3.1  Fineness (sieve residue)  ................................ ................................ ................................ .......................  5 
5.3.2  Initial setting time  ................................ ................................ ................................ ................................ .. 5 
5.3.3  Final setting t ime ................................ ................................ ................................ ................................ ... 5 
5.3.4  Soundness  ................................ ................................ ................................ ................................ .............  5 
5.3.5  Fresh mortar requirements  ................................ ................................ ................................ ..................  5 
5.3.6  Compre ssive strength ................................ ................................ ................................ ...........................  5 
5.3.7  Chemical requirements  ................................ ................................ ................................ .........................  6 
5.4 Durability requirements  ................................ ................................ ................................ ........................  6 
6 Standard designation  ................................ ................................ ................................ ............................  7 
7 Conformity criteria  ................................ ................................ ................................ ................................  7 
7.1 General requirements  ................................ ................................ ................................ ...........................  7 
7.2 Conformity criteria for physical, mechanical and chemical properties and evaluation 
procedure  ................................ ................................ ................................ ................................ ...............  7 
7.2.1  General  ................................ ................................ ................................ ................................ ...................  7 
7.2.2 Statistical conformity criteria  ................................ ................................ ................................ ...............  7 
7.2.3  General  ................................ ................................ ................................ ................................ ...................  7 
7.2.4  Inspection by variables  ................................ ................................ ................................ .........................  9 
7.2.5  Inspection by attributes  ................................ ................................ ................................ ......................  10 
7.2.6  Single result conformity criteria  ................................ ................................ ................................ ........  11 
7.2.7  Conformity criteria for masonry ce ment composition  ................................ ................................ .... 11 
8 Marking, labelling, packaging and storage  ................................ ................................ .......................  12 
8.1 Marking and labelling  ................................ ................................ ................................ ..........................  12 
8.2 Packaging and storage  ................................ ................................ ................................ .......................  12 
Annex  A (inforrmative)  ................................ ................................ ................................ ................................ ..... 14 
A.1 General  ................................ ................................ ................................ ................................ .................  14 
A.2 Safety  ................................ ................................ ................................ ................................ ....................  14 
A.2.1  Manual handling of bags and safety in use  ................................ ................................ ......................  14 
A.2.2  Hazards  ................................ ................................ ................................ ................................ .................  14 
A.2.3  First aid measures  ................................ ................................ ................................ ...............................  15 
A.2.4  Use of personal protective equipment (PPE)  ................................ ................................ ...................  15 
A.2.5  Test tem perature  ................................ ................................ ................................ ................................ . 15 
A.2.6  Rendering and plastering  ................................ ................................ ................................ ...................  15 
A.2.7  Use of masonry cement in mortar  ................................ ................................ ................................ ..... 15 
 DRS 426-1: 2020 
©RSB yyyy - All rights reserved                  iv 
 Foreword   
Rwanda Standard s are prepared  by Technical Committees and approved by R wanda 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 
adopted by Technical committ ees are ratified  by me mbers of RSB Board of Director s for publication and 
gazettment as Rwanda Standards.  
DRS 426-1 was prepared by Technical Committee RSB/TC 09, Civil Engineering and Building Materials  
In the preparation of this standard, reference was made to the following standard  (s): 
1) EAS 73:2000: Building limes (quicklime and hydrated lime) —Specification and met hods  
2) RS EAS 18 -2, Cement — Part 2: Conformity evaluation  
3) RS EAS 131 -1, Concrete — Part 1: Specification, performance, production and conformity  
4) RS EAS 148 -1, Cement — Test methods — Part 1: Determination of strength  
5) RS EAS 148 -2, Cement — Test methods  — Part 2: Chemical analysis of cement  
6) RS EAS 148 -3, Cement — Test methods  — Part 3: Determination of setting time and soundness  
7) RS EAS 148 -5, Cement — Test methods  — Part 5: Pozzolanicity test for Pozzolanic cements  
8) RS 211 -3: 2010 Mortar for masonry - Metho ds of Test: Part 3: Determination of consistence of fresh 
mortar (by flow table)  
9) RS EAS 148 -6: 2018 Cements  — Test methods  — Part 6: Determination of fineness   
10) ASTM C187 - 16  Standard Test Method for Amount of Water Required for Normal Consistency of 
Hydraulic Cement Paste  
The assistance de rived from the above source is hereby acknowledged with thanks.  
DRS 426 consists of the following parts, under the general title Masonry Cement  — 
Part 1: Composition, specifications and  Conformity criteria  
 Part 2: Test methods  DRS 426-1: 2020 
v                ©RSB yyyy - All rights reserved  
 Committee membership  
The following organizations were represented on the Technical Committee on Civil Engineering and Building 
Materials  (RSB/TC 09) in the preparation of this standard.  
City of Kigali  
Green Effect Engineering  
Integrated Polytechni c Regional Centre –Kigali (IPRC)  
NPD  
REAL Contractors Ltd  
Rwanda Housing Authority (RHA)  
Rwanda Transport Development Agency (RTDA)  
Standard For Sustainability (SFS)  
TEMACO Builders  
Gasabo 3D  
Masss Design Group - Rwanda  
Institut d’ Enseignement Supérieur ( INES - Ruhengeri ) 
Amajyambere Industry Co Ltd  
NPD Ltd  
Rabbit Construction Ltd  
Institution of Engineers Rwanda  
CIMERWA Ltd  
University of Rwanda – College of Science and Technology (UR -CST)  
Rwanda Standards Board (RSB) – Secretariat  
 DRS 426-1: 2020 
©RSB yyyy - All rights reserved                  vi 
 Introduction   
The basis for this national standard has been the East African standards already existing in the region.  These 
national standards differ from each other; some of the differences  relate to important principles of definition 
and specification of properties and composi tion. 
Masonry cement should be defined and specified precisely with sufficiently stringent requirements to satisfy 
those who are responsible for the design and construction of buildings and other structures for maximum 
safety and durability.  
 
 DRS 426-1: 2020 
1                ©RSB yyyy - All rights reserved  
 Masonry Cem ent — Part 1 : Composition, specifications and conformity 
criteria  
1 Scope   
This Draft Standard specifies the definition and composition of masonry cements as commonly used for the 
production of mortar for bricklaying and block -laying and for rendering and pl astering. It includes physical, 
mechanical and chemical requirements and defines strength classes. It also states the conformity criteria and 
the related rules. Necessary durability requirements are also given.  
NOTE For normal applications the information given in this draft standard, in RS 108 and in RS 211 is generally sufficient. 
However, in special cases, an exchange of additional information between the masonry cement producer and user can be 
helpful. The details of such an exchange are not within the scope of this draft standard but should be dealt with in 
accordance with national standards or other regulations or can be agreed between the parties concerned.  
2 Normative references   
The following documents are referred to in the text in such 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 EAS 148 -1, Cement — Test methods — Part 1: Determination of strength  
RS EAS 148 -2, Cement — Test methods  — Part 2: Chemical analysis of cement  
RS EAS 148 -3, Cement — Test methods  — Part 3: Determination of setting time and soundness  
RS EAS 148 -6, Cement — Test methods  — Part 6:  Determination of fineness  
RS EAS 148 -7, Cement — Test methods  — Part 7: Methods of taking and preparing samples of cement  
RS EAS 148 -2, Cement — Test methods  — Part 2: Chemical analysis of cement  
RS EAS 18 -1: Cement — Part 1: Composition, specification a nd conformity criteria for common cements  
RS EAS 18 -2, Cement — Part 2: Conformity evaluation  
3 Terms and definitions   
For the purposes of this standard, the follow ing terms and definitions apply   
©RSB yyyy - All rights reserved                  2 
 3.1 
masonry cement  
factory made finely powdered hydraulic bin der which relies essentially upon the presence of Portland cement 
clinker to develop strength. When mixed with sand and water only and without the addition of further materials 
it produces a workable mortar suitable for use in rendering, plastering and mas onry work  
3.2 
additives  
constituents which are added to improve the manufacture or the properties of the masonry cement, e.g. 
grinding aids, air -entraining agents  
3.3 
autocontrol testing  
continual testing by the manufacturer, of masonry cement spot samples  taken at the point(s) of release from 
the factory/depot  
3.4 
control period  
period of production and despatch identified for the evaluation of the autocontrol test results  
3.5 
characteristic value  
value of a required property outside of which lies a specif ied percentage, the percentile P k, of all the  values of 
the population  
3.6 
specified characteristic value  
characteristic value of a mechanical, physical or chemical property which in the case of an upper limit is  not to 
be exceeded or, in the case of a low er limit is, as a minimum, to be reached  
3.7 
single result limit value  
value of a mechanical, physical or chemical property which, for any single test result as in the case of an  
upper limit is not to be exceeded or, in the case of a lower limit is, as a m inimum, to be reached  DRS 426-1: 2020 
3                ©RSB yyyy - All rights reserved  
 3.8 
allowable probability of acceptance CR  
for a given sampling plan, the allowed probability of acceptance of masonry cement with a characteristic  value 
outside the specified characteristic value  
3.9 
sampling plan  
specific plan which  states the (statistical) sample size(s) to be used, the percentile P k and the allowable  
probability of acceptance CR  
3.10 
spot sample  
sample taken at the same time and from one and the same place, relating to the intended tests. It can be  
obtained by comb ining one or more immediately consecutive increments (see RS EAS 148 -7) 
4 Symbols and abbreviated terms   
Masonry cement shall be designated by the term 'MC'.  
There shall be three strength classes of masonry cement, 5, 12.5 and 22.5.  
The term 'X' designates m asonry cements in which an air entraining agent is not incorporated.  
5 Requirements  
5.1 General  
The physical, mechanical and chemical properties of masonry cements shall be measured by the test  
methods described in PD XXX -2 (under development)  and in the rele vant parts of RS EAS 148. These East 
African Standards give alternative test methods for some properties but in the event of a dispute only the 
reference methods shall be used. Where allowed in the relevant part of RS EAS 148, different methods may 
be used  provided they give correlated and equivalent values to those obtained using the reference method.  
The Standard sand conforming to the requirements of RS EAS 148 -1 used to make the mortars for the tests 
required by 5.3.5 and 5.3.6 shall have a silica conte nt (as quartz) of not less than 93 %.  
All requirements are specified as characteristic values. They serve to define the performance level  and 
classification of the masonry cements.  
  
©RSB yyyy - All rights reserved                  4 
 5.2 Constituents and composition  
5.2.1 Masonry cement shall comprise Portland cement clinker, inorganic constituents and where appropriate 
additive(s) as given in Table 1. Calcium sulfate is added in small quantities to the other constituents of 
masonry cement during its manufacture to control setting.  
 
5.2.2 The inorganic constitue nts of masonry cements conforming to this standard shall be  materials 
 selected from:  
natural mineral materials;  
mineral materials used for or derived from the clinker production process;  
hydrated and/or hydraulic building limes conforming to EAS  73-1; 
constituents specified in EAS 18 -1; 
inorganic pigments (except those contai ning carbon black)  
 
NOTE : Carbon black has a detrimental effect upon the air entrainment.  
5.2.3 Additives shall not promote corrosion of embedded metal such as reinforc ement and wall ties or  impair 
the properties, including behaviour in fire, of the mortar made from the masonry cement.  and Organic 
pigments shall  not permitted.  
Table 1 - Composition of masonry cements  
Type  Content  
% by mass  
Portland Cement clinker  Addit ives 
MC 5  > 25 
<  1a MC 12 .5 
MC 12.5 X, MC 22.5 X  >  40 
a The quantity of organic additives on a dry basis shall not exceed 0,5 % by mass of the masonry cement.  
5.2.4  The manufacturing process and its control shall ensure that the composition of mason ry cement is kept 
within the limits provided in this draft standard. Masonry cements consist ultimately of individual small grains 
of different materials and are statistically homogeneous in composition resulting from quality assured 
production and materia l handling processes.  
5.2.5 A high degree of uniformity in all masonry cement properties shall be obtained through mass production 
processes, in particular, adequate grinding and homogenization. Qualified and skilled personnel and the 
facilities to test, e valuate and adjust product quality are indispensable for producing masonry cement in 
accordance with this Draft Standard.   DRS 426-1: 2020 
5                ©RSB yyyy - All rights reserved  
 5.3 Physical and mechanical requirements  
5.3.1  Fineness (sieve residue)  
The residue on a 90 m sieve shall be not more than 15 % by mass when d etermined in accordance with RS 
EAS 148 -6. 
5.3.2  Initial setting time  
The initial setting time shall be not less than 60 min when determined in accordance with Part 2 of this Draft 
standard - under development.  
5.3.3  Final setting time  
Where the initial setting time i s less than 6 h, there is no requirement for final setting time. Where theinitial 
setting time is 6 h or more, the final setting time shall be not more than 15 h when determined in accordance 
with DRS 426 -2  (under development ). 
5.3.4  Soundness  
The expansion sha ll be not more than 10 mm when determined in accordance with RS EAS 148 -3. 
5.3.5  Fresh mortar requirements  
The properties of air content and water retention of fresh mortar shall be measured in accordancewith  DRS 
426-2 (under development),  on a mortar of standar d consistence which shall have a value of penetration of 
(35 ± 3) mm using the plunger apparatus as the reference method. The flow table test is the alternative 
method. The test results shall meet the requirements given in Table 2.  
NOTE An air -entraining a gent is incorporated into the masonry cements of lower strength classes to improve their 
workability and durability. An upper limit is set for air content to maintain good bond strength to masonry units. The water 
retention limits are specified for all cla sses of masonry cement to provide a performance suitable for use with high suction 
masonry units.  
Table 2 - Fresh mortar requirements given as characteristic values  
Type  Air content  
% by volume  Water retention  
% by mass  
MC 5  8 and 22 80 
MC 12.5 X  
MC 22.5 X  6 a 75 
a The control of the masonry cement manufacturing process ensures that this upper limit is not exceeded.  
 
5.3.6  Compressive strength  
The compressive strength when determined in accordance with RS EAS 148 -1at the fixed water/masonry 
cement ratio of 0,50 shall have the values given in Table 3.   
©RSB yyyy - All rights reserved                  6 
  
Should it not be possible to remove the prisms from the moulds after 24 h, it is permitted to remove  
them at 48 h. Where the prisms are demoulded at 48 h this shall be reco rded.  
 
RS EAS 148 -1 gives repeatability and reproducibility values for 28 day strength. On account of their lower  
strengths, values of 4 % and 8 % respectively are appropriate for masonry cements conforming to this  
Draft  Standard.  
 
Table 3 - Compressive s trength requirements given as characteristic values  
Type  7 day (early) strength MPa  28 day (standard) strength MPa  
MC 5  -- 5 a 15 a 
MC 12,5  
MC 12,5 X  7 12,5 32,5 
MC 22,5 X  10 22,5 42,5 
a A loading rate of (400 ± 40) N/s shall be used wh en testing specimens of type MC 5.  
 
 
5.3.7  Chemical requirements  
The properties of the masonry cement shall conform to the requirements given in Table 4 when determined by 
the method indicated in this Table.  
Table 4 - Chemical requirements given as characterist ic values  
Property  Reference test  
method  Type  Value  
% by mass  
Sulfate content (as  
SO3) 
RS EAS 148 -2 MC 5  2.0 
MC 12.5  
MC 12.5 X  
MC 22.5 X  3,0 a 
Chloride content  
(as CI)  MC 5  No requirement  
MC 12.5  
MC 12.5 X  
MC 22.5 X  < 0.10 
a 3,5 % if the Portland cement clinker content can be shown to be not less than 55 %.  
 
5.4 Durability requirements  
To ensure d urability, the requirements of 5.2 shall be met. In many applications, particularly in severe 
environmental conditions, the choice of masonry cement type from this standard has an influence on the 
durability of mortar. The choice of masonry cement type for  different applications and exposure classes shall 
follow the appropriate standards and/or regulations valid in the place of use of the mortar.  DRS 426-1: 2020 
7                ©RSB yyyy - All rights reserved  
 6 Standard designation  
Masonry cement conforming to this Draft Standard shall be identified using the notation in clause 4, i.e. the 
symbol 'MC', followed by the strength class and when relevant, by the letter 'X'.  
EXAMPLE Masonry cement EN 413 -1 MC 12,5 X.  
7 Conformity criteria  
7.1 General requirements  
Conformity of masonry cement to this European Standard shall be continu ously evaluated on the basis of 
testing spot samples. The properties, test methods and the minimum testing frequencies for the autocontrol 
testing by the manufacturer are specified in Table 5. Concerning testing frequencies for masonry cement not 
being des patched continuously and other details, refer to RS EAS 18 -2. 
For certification of conformity by an approved certification body, conformity of masonry cement to this 
European Standard shall be evaluated in accordance with RS EAS 18 -2. 
NOTE -This Draft Stan dard does not deal with acceptance inspection at delivery.  
7.2   Conformity criteria for physical, mechanical and chemical properties and  evaluation 
procedure  
7.2.1  General  
Conformity of masonry cement with physical, mechanical and chemical requirements in 5.3  is assumed if the 
conformity criteria specif ied in 7.2.2 and 7.2.3  are met. Conformity shall be evaluated on the basis of continual 
sampling using spot samples tak en at the point of release and on the basis of the test results obtained on all 
autocontrol s ampl es taken during the control period.  
7.2.2  Statistical conformity criteria  
7.2.3  General  
Conformity shall be formulated in terms of a statistical criterion based on:  
the required characteristic values for physical, mechanical and chemical properties as specified in  
  5.3  and 5.4;  
the percentile P k on which the specified characteristic value is based, as specified in Table 6;  
the allowable probability of ac ceptance CR as specified in Table 6.  
Conformity with the requirements of this Draft Standard shall be verified either by variables or by  attributes, as 
described in 7.2.2.2 and 7.2.2.3 as specified in Table 5.   
©RSB yyyy - All rights reserved                  8 
 The control period shall be 24 months.  
Table 5  - Properties, test methods and minimum testing frequencies for the autocontrol testing by the 
manufacturer, and the statistical assessment procedure  
Property   
Masonry 
cements to be 
tested   
Test  
method a. b Autocontrol  testing  
Minimum testing frequen cy Statistical assessment 
procedure  
Routine 
situation  Initial period  
for a new  
type of  
masonry 
cement  Inspection by  
Variables d Attributes f 
1 2 3 4 5 6 7 
Strength  
     - 7 days  
- 28 days   
all except MC 5  
All RS EAS 148 -1e 1 each 2 
weeks  2/week   X 
Initial setting 
time All Part 2 of this 
standard  1 each 2 
weeks  2/week   X 
Final setting 
time as appropriate  Part 2 of this 
standard     X 
Soundness  
(expansion)  All RS EAS 148 -3 1/month  1/week   X 
Sieve 
residue  All RS EAS 148 -6 1/month  1/week   X 
Air content  MC 5, MC 12,5  Part 2 of this 
standard  1/week  4/week   X 
Water 
retention  All Part 2 of this 
standard  1/month  1/week   X 
Sulfate 
content  All RS EAS 148 -2 1 each 2 
weeks  2/week   X 
Chloride 
content  All except MC 5  RS EAS 148 -2 1/month  1/week   X 
Compo sition  All - c 1/month  1/week   X 
a Where allowe d in the relevant part of RS EAS 148 , other methods than those indicated may be used provided they give results 
correlated  and equivalent to those obtained with the reference method (except initial type testi ng). 
b The methods used to take and prepare samples shall be in accordance  with the requirements of RS EAS 148 -7. 
c Appropriate method chosen by the manufacturer and for which a correlation with the method(s) used for initial type testing ca n be 
establishe d. 
d If the data are not normally distributed, then the method of assessment may be decided on a case by case basis.  
e See 5.3.6.  
f If the number of samples is at least 1 each week during the control period, the assessment may be made by variables.  
 
 
Table 6 - Required values of P k and CR  
 Air content (upper limit)  
28 day strength (lower limit)  All other requirements  DRS 426-1: 2020 
9                ©RSB yyyy - All rights reserved  
 The percentile P k on which the 
characteristic value is based  5 % 10 %  
Allowable probability of  
acceptance CR  5 % 
NOTE - Conformity evaluat ion by a procedure based on a finite number of test results can only produce an approximate 
value for the proportion of results outside the specified characteristic value in a population. The larger the sample size 
(number of test results), the better the approximation. The selected probability of acceptance CR controls the degree of 
approximation by the sampling plan.  
 
7.2.4  Inspection by variables  
For this inspection, the test results are assumed to be normally distributed. Conformity is verified when 
equations  (1) and (2), as relevant, are satisfied.  
 and     
                                                                                (1) 
     
                                                                                  (2) 
Where,  
  x  -  is the arithmet ic mean of the totality of the autocontrol test results in the control period;  
  s  - is the standard deviation of the totality of the autocontrol test results in the control period;  
  kA -  is the acceptability constant;  
  L -  is the specified lower limi t given in Tables 2 and 3;  
  U -  is the specified upper limit given in Tables 2, 3 and 4.  
The acceptability constant k A depends on the percentile P K on which the characteristic value is based, on the 
allowable probability  of acceptance CR and on the numbe r n of the test results. Values of k A are listed in Table 
7. 
  
 
  
©RSB yyyy - All rights reserved                  10 
  
 
 
Table 7 - Acceptability constant  
Number of test results n  kAa 
for P k = 5 % b for P k = 10 % c 
20 to 21  2.40 1.93 
22 to 23  2.35 1.89 
24 to 25  2.31 1.85 
26 to 27  2.27 1.82 
28 to 29  2.24 1.80 
30 to 34  2.22 1.78 
35 to 39  2.17 1.73 
40 to 44  2.13 1.70 
45 to 49  2.09 1.67 
50 to 59  2.07 1.65 
60 to 69  2.02 1.61 
70 to 79  1.99 1.58 
80 to 89  1.97 1.56 
90 to 99  1.94 1.54 
100 to 149  1.93 1.53 
150 to 199  1.87 1.48 
200 to 299  1.84 1.45 
300 to 399  1.80 1.42 
400 1.78 1.40 
NOTE Values given in this table are valid for CR = 5 %.  
a The value of k A valid for each intermediate value on n may be used instead.  
b For air content (upper limit) and 28 days strength (lower limit).  
c For all other strength, physical and chemical requirements.  
 
7.2.5  Inspection by attributes  
The number c D of test results outside the characteristic value shall be counted and compared with an 
acceptable number c A calculated from the number n of autocontrol test results and the percentile P k as 
specified in Table 8. Conformity is verified when the following equation (3) is satisfied:  DRS 426-1: 2020 
11                ©RSB yyyy - All rights reserved  
    CD < CA                                                                                                                                    (3) 
The value of c A depends on the percentile P k on which the characteristic value is based, on the allowable 
probability of acceptance CR and on a number n of the test results. Values of c A are listed in Table 8.  
Table 8 - Values of C A 
Number of test  
result s n a 
Pk = 10 %  CA Number of test  
results n a 
Pk = 5 %  
20 to 39  0 20 to 79  
40 to 54  1 80 to 109  
55 to 69  2 110 to 139  
70 to 84  3 140 to 169  
85 to 99  4 170 to 199  
100 to 109  5 200 to 219  
110 to 123  6 220 to 247  
124 to 136  7 248 to 273  
NOTE Values g iven in this table are valid for CR = 5 %  
a If the number of test results is n 20 a statistically based conformity criterion is not possible. Despite this, a criterion of cA = 0 shall be 
used in case where n 20. 
 
7.2.6  Single result conformity criteria  
In addition to the statistical conformity criteria, conformity of test results with the requirements of this Draft 
Standard requires that it shall be verified that each test result remains within the single result limit values 
specified in Table 9.  
7.2.7  Conformity  criteria for masonry cement composition  
At least once per month the composition of the masonry cement shall be checked by the manufacturer, using 
as a rule a spot sample taken at a point of release. The masonry cement composition shall meet the 
requiremen ts specified in 5.2. The limiting quantities of the Portland cement clinker specified in Table 1 are 
reference values to be met by the average composition calculated from the spot samples taken in the control 
period. For single results, maximum deviations of -2 from the reference value are allowed. Suitable 
procedures during production and appropriate verification methods to ensure conformity to this requirement 
shall be applied and documented.  
Table 9 -- Limit values for single results  
Property  Limit valu es for single results   
 MC 5  MC 12.5  MC 12.5 X   MC 22.5 X  
Strength (MPa)  
lower limit value   
--  
6  
6  
9  
©RSB yyyy - All rights reserved                  12 
 7 day  
28 day   
4  
10.5  
10.5  
20.5 
Strength (MPa)  
upper limit value  
28 day   
17.5  
37.5  
37.5  
47.5 
Initial setting time (min) lower limit 
value  45 
Final setting time (h) upper limit 
value  17a 
Soundness (expansion in mm) 
upper limit value  10 
Sulfate content (as % SO 3) upper 
limit value   
2.5  
3.5b  
3.5b 
  
3.5b 
Chloride content (%) upper limit 
value   
--  
0.10  
0.10  
0.10 
Water retention (%) lower li mit 
value   
75  
70 
Air content (%) lower limit value  
upper limit value  6 
25 6 
25 - 
 
- -- 
 
-- 
a Where appropriate (see 5.3.3).  
b  4,0 % if the Portland cement clinker content can be shown to be not less than 55 %.   
 
8 Marking, labelling, packaging and stora ge 
8.1 Marking and labelling  
Each bag of cement shall be legibly and indelibly marked with the following information  in English language : 
a) the manufacturer’s name , address, (fac tory physical address)and/or  trademark;  
b) standard designation of cement;  
c) net weight o f cement in kilograms;  
d) date of packing and/or batch number  
8.2 Packaging and storage  
8.2.1 The cement shall be packaged in a material that safeguards the quality,  safety and integrity of the 
product.  DRS 426-1: 2020 
13                ©RSB yyyy - All rights reserved  
 8.2.2 The cement shall be stored in dry and cool place that  allows easy access for inspection and 
identification, and in suitable waterproof building to maintain quality of the cement. It shall be stored on pallets 
not in contact with the walls / floors and roof.  
 
  
©RSB yyyy - All rights reserved                  14 
 Annex  A 
(inforrmative)  
Guidance on use of the product  
A.1 General  
Guidance on the use  and selection  of masonry c ement in mortar shall be found in RS 108  table 1A.  
A.2 Safety  
A.2.1  Manual handling of bags  and safety in use  
 Manual handling activities are subject, and users' obligations there under. Where manual handling oper ations 
cannot be avoided,  RS ISO 45001 clause 6.1 and national labor regulations shall be taken into account,  the 
risks have to be assessed and reduced so far as is reasonably practicable. It is recommended that the use of 
25 kg bags of cement in order t o reduce the risk of injury.  
Work with cement is subject, and users' obligations thereunder. Cements based on Portland cement clinker 
have been classified as irritants, and users' obligations thereunder.  The following precautions shall be 
considered during  manual handling of cement  for the safety of users:  
a) the heal th risks of the cement in use should be  assessed and then prevented or controlled;  
b) product health and safety information sheets should be made available from the 
manufacturer/supplier;  
c) ba gs containing masonry cement should be  labelled with a health and safety warning indicating that 
the cement is an irritant;  
A.2.2  Hazards  
 When masonry cement becomes damp or is mixed with water,  to make mortar, a concentrated alkaline 
solution is produced. Wher e this comes into contact with the eyes or skin, it may cause  serious burns and 
ulceration. The eyes are particularly vulnerable and injury will increase with  contact time.  
Concentrated alkaline solutions, in contact with skin, tend to damage the nerve end ings first before  damaging 
the skin, therefore chemical burns can develop without pain being felt at the time.  In addition, cement mortar 
can, until it has set, cause both irritant and allergic contact dermatitis:  
a) irritant contact dermatitis results fro m a combination of the moisture content, alkalinity and  abrasiveness of 
cement mortar;  
b) allergic contact dermatitis is mainly a consequence of the sensitivity of an individual's skin to  water -soluble 
hexavalent chromium, in solution.  High repeated exposu res, to airborne cement, in excess  of the regulatory 
limit have been linked with rhinitis and coughing.  DRS 426-1: 2020 
15                ©RSB yyyy - All rights reserved  
 A.2.3   First aid measures  
 a) In the event that eyes come into contact with masonry cem ent, wash eyes immediately with copious 
 amounts of clean water for a p eriod of at least 15 minutes and seek medical advice without delay.  
b)  In the event that skin comes into contact with masonry cement, wash the affected area thoroughly with 
 soap and water before continuing the activity. If irritation, pain or skin troubl e occurs, seek medical 
 advice.  Clothing or footwear contaminated by wet cement, or cement -mortar should be removed and 
 washed immediately and thoroughly before being reused.  
A.2.4    Use of personal protective equipment (PPE)  
  a)  Where the risk of cement beco ming airborne can be neither prevented nor completely controlled, 
 attention  is drawn to relevant regulations on the control of hazardous substances in the environment  
 which specify  a regulatory exposure limit. T he use of appropriate respiratory protect ive equipment to 
 ensure that  exposure is less than the Occupational Exposure Standard ( OES ), and users' obligations 
 thereunder. In  addition, dustproof goggles should be worn in order to protect the eyes.  
b)  Where the risks from contact with wet cement  or wet mortar can be neither prevented nor  completely 
 controlled, appropriate protective equipment should be worn as follows.  
 1)    Waterproof protective clothing should be worn in order that cement, or any cement and  water   
  mixture,  e.g. mortar, do es not come into contact with the skin. Should wet mortar  enter    
  waterproof footwear, waterproof gloves or other waterproof protective clothing, then  the item(s) of  
  clothing should be removed immediately and the skin thoroughly washed with  soap and water. Items 
  of waterproof protective clothing that have been worn should be  washed before reuse.  
 2)  Where this appropriate protective equipment takes the form of eye protection , wherever  there is a  
  risk of cement, or any wet cement mixture, enterin g the eye, dustproof goggles  should be worn.  
A.2.5  Test temperature  
Rwanda Standard test methods for testing masonry mortar (RS 211) require that standardized properties are  
tested at specified target temperatures, subject to specified tolerances. If cement is t ested under  different 
temperature conditions, the results are likely to be affected. Appropriate advice on how  different temperature 
conditions can affect results should be available from the manufacturer.  
A.2.6  Rendering and plastering  
Where masonry cement is t o be used in renders or plasters that are pumped through small apertures,  such as 
spray nozzles, it is recommended that the user passes the cement or suspension through a  screen of suitable 
mesh aperture to retain any occasional coarse particles.  
A.2.7  Use of ma sonry cement in mortar  
The mix proportions (by volume) required to produce any given type of prescribed mortar will vary  depending 
on the composition and bulk density of the masonry cement. Manufacturers' advice  should be followed to 
achieve the required  type.   
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 The compositional possi bilities covered in this Draft Rwanda  Standard permit the use of masonry cements  
that contain lower clinker contents than the ty pe MC 12,5 . Although  information can be obtained about the 
working properties, such as workability  of these other masonry cements specified in this standard, there is as 
yet no information  available on the durability of these other masonry cemen ts when they are subjected to 
severe  climatic  conditions. In particular, type MC 5 may be considered to be un suitable for external masonry 
and non air entrained types MC 12,5 X and MC 22,5 X may be considered to be more  susceptible to severe 
climatic conditions.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 DRS 426-1: 2020 
17                ©RSB yyyy - All rights reserved  
 Bibliography  
[1] EN 197 -1: 2011; Cement – Part 1; Composition, specifications and conform ity criteria for common 
cements  
[2] EN 413 -1, Masonry cement — Part 1: Composition, specifications and conformity criteria  
[3] ISO 5725 -2, Accuracy (trueness and precision) of measurement methods and results — Part 2: Basic method 
for the determination of repeata bility and reproducibility of a standard measurement method  
 DRS 426-1: 2020  
 
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