ICS 91.080 .30 
 
Reference number  
DRS 108: 2020  
© RSB 2020  
  
 RWANDA 
STANDARD  DRS  
108 
second  edition  
2020 -mm-dd 
 
Mortar for masonry  — Specification  
 
 DRS 108: 2020  
©RSB 2020  - 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 t hat they are in possession of the latest 
edition  
 
 
 
 
 
 
 
 
© RSB 2020  
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 an d 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 788303492  
Toll Free: 3250  
E-mail: info@rsb.gov.rw  
Website: www.rsb.gov.rw  
ePortal: www.portal.rsb.gov.rw   DRS 108: 2020  
iii                ©RSB 2020  - All rights reserved  
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ ..........................  ivv 
1 Scope  ................................ ................................ ................................ ................................ ......................  1 
2 Normative references  ................................ ................................ ................................ ............................  1 
3 Terms and definitions  ................................ ................................ ................................ ...........................  1 
4 Materials  ................................ ................................ ................................ ................................ ...............  67 
4.1 General  ................................ ................................ ................................ ................................ .................  67 
4.2 Water  ................................ ................................ ................................ ................................ .....................  67 
4.3 Aggregates  ................................ ................................ ................................ ................................ ...........  67 
4.4 Cementitious Materials  ................................ ................................ ................................ .........................  7 
4.5 Cement  ................................ ................................ ................................ ................................ ...................  7 
4.5.1  Lime  ................................ ................................ ................................ ................................ ......................  78 
5 Requirements for Mortar ................................ ................................ ................................ .....................  78 
5.1 General  ................................ ................................ ................................ ................................ .................  78 
5.2 Properties of fresh mortar  ................................ ................................ ................................ ..................  78 
5.2.1  Workable life  ................................ ................................ ................................ ................................ ........  78 
5.2.2  Workability  ................................ ................................ ................................ ................................ .............  8 
5.2.3  Chloride content  ................................ ................................ ................................ ................................ .. 89 
5.2.4  Air content  ................................ ................................ ................................ ................................ ............  89 
5.3 Proportion of constituents  ................................ ................................ ................................ .................  89 
5.4 Properties of hardened mortar  ................................ ................................ ................................ .............  9 
5.4.1  Compressive strength of mortar for bedding masonry units  ................................ ...........................  9 
5.4.2  Comp ressive strength of rendering/plastering mortar  ................................ ................................ .... 10 
5.4.3  Bond strength  ................................ ................................ ................................ ................................ .. 1112 
5.4.4  Water absorption  ................................ ................................ ................................ .............................  1112 
5.4.5  Density (dry hardened mortar)  ................................ ................................ ................................ ....... 1112 
5.5 Mixing of mortar  ................................ ................................ ................................ ................................ .. 12 
5.5.1  Machine mixing  ................................ ................................ ................................ ................................ .... 12 
5.5.2  Hand mixing  ................................ ................................ ................................ ................................ ..... 1213 
6 Designation of masonry mortar manufactured in a plant  ................................ ...........................  1213 
7 Marking ................................ ................................ ................................ ................................ .................  13 
8 Evaluation of conformity  ................................ ................................ ................................ ................  1314 
8.1 General  ................................ ................................ ................................ ................................ .............  1314 
8.2 Plant product ion control  ................................ ................................ ................................ .................  1314 
8.2.1  General  ................................ ................................ ................................ ................................ .............  1314 
8.2.2  Process control  ................................ ................................ ................................ ...............................  1314 
8.2.3  Finishe d product test  ................................ ................................ ................................ ..........................  14 
8.2.4  Traceability  ................................ ................................ ................................ ................................ ....... 1415 
 DRS 108: 2020  
©RSB 2020  - 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 tanda rds 
adopted by Technical committ ees are ratified  by me mbers of RSB Board of Director s for publication and 
gazettment as Rwanda Standards.  
DRS 108 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) BS EN 998 -1, Specification for mortar for masonry, Part 1: Rendering/plastering mortar  
2) BS EN 998 -2, Specification for mortar for masonry Part 2: Masonry mortar  
3) ASTM C 270. 8242 -1, Standard speci fication for mortar for unit masonry  
4) BS 5628 -1, Code of practice for the use of masonry, Part 1 Structural use of unreinforced masonry  
The assistance de rived from the above source is hereby acknowledged with thanks.  
This second edition  cancels and replaces  the first edition (RS  108: 2010 ), which has been technically revised.  
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.  
University of Rwanda – College of Science and Technology (UR -CST)  
City of Kigali  
Green Effect Engineering  
Integrated Polytechnic Regional Centre –Kigali (IPRC)  
TECOS Ltd  
NPD  
REAL Contractors Ltd  DRS 108: 2020  
v                ©RSB 2020  - All rights reserved  
 Rwanda Housing Authority (RHA)  
Rwanda Transport Development Agency (RTDA)  
Gasabo 3D  
BJ Construction Ltd  
Masss Design Group - Rwanda  
Institut d’ Enseignement Supérieur (INES - Ruhengeri)  
NPD Ltd  
EAG Industries Ltd  
Institution of Engineers Rwanda  
CIMERWA Ltd  
Rwanda Standards Board (RSB) – Secretariat  
 DRS 108: 2020  
1                ©RSB 2020  - All rights reserved  
 Mortar for maso nry — Specifications  
1 Scope   
This Draft Rwanda S tandard specifies requirements for masonry mortars for bedding, jointing and pointing in 
masonry walls,  columns and partitions (facing and rendered masonry, load bearing or non -load bearing 
masonry structures  for building and civil engineering).  
This standard specifies requirements for rendering and plastering mortar used on walls, ceilings, columns and  
partitions.   
It defines the performance related to workable life for fresh mortars. For hardened mortars it d efines  
performances related to compressive strength, bond strength and density and provides the evaluation of  
conformity of the product based on tests.  
It applies to mortars mixed in a plant or on site.  
2 Normative references  
The following documents are refe rred 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,  
RS EAS 18 -1, Cement — Part 1: Composition, specification and confo rmity criteria for common cement  
CD ASTM C141  Standard Specification for Hydrated Hydraulic Lime for Structural Purposes  
RS 211 -2, Mortar for masonry — Part 2: Bulk sampling of mortars and Preparation of test mortars  
RS 211 -3, Mortar for masonry — Part 3: Determination of consistence of fresh mortar (by flow table)  
RS 211 -4, Mortar for masonry — Part 4: Determination of consistence of fresh mortar ( by plunger 
penetration)  
RS 211 -7, Mortar for masonry — Part 7: Determination of water absorption coefficient due to capillary action 
of hardened mortar . 
3 Terms and definitions   
For the purposes of this document, the following terms and definitions apply.  
3.1 
masonry mortar   
©RSB 2020  - All rights reserved                  2 
 mix of one or more inorganic binders, aggregates, water, and sometimes additions and/or admi xtures for  bedding, 
jointing and pointing of masonry  
3.2 
fresh masonry mortar  
mortar completely mixed and ready for use  
3.3 
designed masonry mortar  
mortar whose composition and manufacturing method is chosen by the producer in order to achieve specified  
properties (performance concept)  
3.4 
prescribed masonry mortar  
mortar made in predetermined proportions, the properties of which are assumed from the stated proportion of  the 
constituents (recipe concept)  
3.5 
general purpose masonry mortar  
masonry mortar wit hout special characteristics  
3.6 
thin layer masonry mortar  
designed masonry mortar with a maximum aggregate size less than or equal to a prescribed figure (see 4.2)  
3.7 
lightweight masonry mortar  
designed masonry mortar with a dry hardened density below a prescribed figure (see 5.4.5)  
3.8 
plant made masonry mortar  
mortar batched and mixed in a plant which is supplied ready for use  
3.9 
prebatched masonry mortar  
mortar whose constituents are wholly batched in a plant supplied to the building site and mixed th ere according to 
the manufacturer's specification and conditions  
3.10 
premixed lime -sand - masonry mortar  DRS 108: 2020  
3                ©RSB 2020  - All rights reserved  
 mortar whose constituents are wholly batched and mixed in a plant, supplied to the building site where further  
constituents specified or provided by th e plant are added (e.g. cement)  
3.11 
site-made masonry mortar  
mortar composed of individual constituents batched and mixed on the building site  
3.12 
binder  
material used to hold solid particles together in a coherent mass, e.g. cement, building lime  
3.13 
aggregate  
granular material that does not contribute to the hardening reaction of the mortar  
3.14 
admixture  
material added in small quantities to produce specified modifications to the properties  
3.15 
addition  
finely divided inorganic material (which is not  an aggregate or binder) that may be added to mortar in order to  
improve or achieve special properties  
3.16 
bond strength  
adhesion perpendicular to the bed between the masonry mortar and the masonry unit  
3.17 
declared value  
value that a manufacturer is con fident in achieving, bearing in mind the precision of test and variability of  process  
3.18 
masonry subjected to severe exposure  
masonry or elements of masonry which are subjected to saturation with water (driving rain, ground water)  combined 
with frequent freeze/thaw -cycling due to climatic conditions, and absence of protective features  
3.19 
masonry subjected to moderate exposure   
©RSB 2020  - All rights reserved                  4 
 masonry or elements of masonry which are exposed to moisture and freeze/thaw -cycling, excluding  constructions 
subjected to severe  exposure  
3.20 
masonry subjected to passive exposure  
masonry or elements of masonry which are not intended to be exposed to moisture and freezing conditions  
3.21 
rendering/plastering mortar  
mix of one or more inorganic binders, aggregates, water and someti mes admixtures and/or additions, used as  
external renders or internal plasters  
3.22 
fresh rendering/plastering mortar  
mortar completely mixed and ready for use  
3.23 
designed rendering/plastering mortar  
mortar whose composition and manufacturing method is c hosen by the producer in order to achieve specified  
properties (performance concept)  
3.24 
prescribed rendering/plastering mortar  
mortar made in pre -determined proportions, the properties of which are assumed from the stated proportion of  the 
constituents ( recipe concept)  
3.25 
plant -made rendering/plastering mortar  
mortar batched and mixed in a plant. It may be 'dry mortar' which is ready mixed only requiring the addition of  water, 
or ' wet mortar' which is supplied ready for use  
3.26 
prebatched rendering/pl astering mortar  
mortar whose constituents are wholly batched in a plant, supplied to the building site and mixed there  according to 
the manufacturer's specification and conditions  
3.27 
premixed lime -sand rendering/plastering mortar  
mortar whose constituent s are wholly batched and mixed in a plant, supplied to the building site where further  
constituents specified or provided by the factory are added (e.g. cement)  
3.28 DRS 108: 2020  
5                ©RSB 2020  - All rights reserved  
 site-made rendering/plastering mortar  
mortar composed of individual constituents batched a nd mixed on the building site  
3.29 
general purpose rendering/plastering mortar  
rendering/plastering mortar without special characteristics. It can be prescribed or designed  
3.30 
lightweight rendering/plastering mortar  
designed rendering/plastering mortar w ith a dry hardened density below a prescribed figure.  
3.31 
coloured rendering mortar  
designed rendering/plastering mortar specially coloured  
NOTE  The colour is achieved with pigments or coloured aggregates.  
3.32 
one coat rendering mortar for external use  
designed rendering mortar applied in one coat which fulfils all the functions of a multicoat system used  externally 
and which is usually specifically coloured. One coat mortars for external use may be manufactured  using normal 
and/or lightweight aggregates  
3.33 
renovation mortar  
designed rendering/plastering mortar used on moist masonry walls containing water soluble salts. These  mortars 
have a high porosity and vapour permeability and reduced capillary action  
3.34 
render/plaster  
materials used externally ar e referred to as render/rendering and materials used internally as  plaster/plastering  
3.35 
rendering/plastering system  
sequence of coats to be applied to a background which can be used in conjunction with the possible use of a  
support and/or reinforcement and/or a pre -treatment  
NOTE  In some cases the pre -treatment may be regarded as a separate coat in addition to the specified system.  
3.36 
render/plaster coat   
©RSB 2020  - All rights reserved                  6 
 layer applied in one or more operations or passes with the same mix, with the previous pass not bei ng allowed  to 
set before the next one is made (i.e. fresh on fresh)  
3.37 
undercoat  
lower coat or coats of a system  
3.38 
final coat  
last coat, decorative or not, of a multicoated rendering or plastering system  
4 Materials  
4.1 General  
4.1.1  Raw materials shall hav e characteristics permitting the finished product to conform to the 
requirements of this standard.  
4.1.2  Mortar is a combination of water, aggregate, and cementitious materials. Each ingredient serves an 
important purpose in the mix.  
4.2 Water  
Water assists th e mixing of the aggregate and cementitious materials. Adequate water is essential for  
hydration, workability and chemical process that gives mortar its strength. Potable water shall be used in  
mortar because water that is safe to drink generally does not c ontain contaminants that may adversely affect  
mortar properties.  
4.3 Aggregates  
Aggregate used in mortar is usually sand and resists shrinkage of the cement in the mortar mix. For  
workability and strength, each particle of aggregate shall be coated with a comb ination of cementitious  
material and water. If sand particles of uniform size (large or small) are used in the mortar, the total volume of  
voids between particles is greater and more of the cementitious material is required in the mix than if sand  
particle s of varying sizes are used.  
Well-graded sand, containing hard particles of varying sizes from dust up to about 2 mm shall be desirable  
because the required proportion of cementitious materials to aggregate is decreased, as is the total volume of  
water use d in the mix. Lower proportions of cement and water or water -cement ratio mean less shrinkage.  
Less shrinkage means less tendency of the mortar to crack. The sand shall be free from grass, leaves, roots,  
and other harmful ingredients.  
The manufacturer of m ortar shall keep records of how suitability of materials is established.  DRS 108: 2020  
7                ©RSB 2020  - All rights reserved  
 4.4 Cementitious Materials  
Cementitious materials have adhesive and cohesive properties both when in a plastic state and when  
hardened. There are two categories of cementitious materials:  cement and lime, and mortar shall include one  
of them or a combination of the two.  
4.5 Cement  
Common cements shall be used and shall comply with RS EAS 18 -1 and shall be kept in dry stores. If there 
are hard lumps in the cement that cannot be crumbled by hand , it is not fresh and should not be used.  
4.5.1  Lime  
Building lime complying with CD ASTM C141M shall be used.  
Lime should be used if the sand lacks fine material or is single sized, as such sands tend to produce mortar 
with poor workability unless lime is inclu ded in the mix.  
Lime also helps the fresh mortar to retain water when it is placed against dry cement bricks or blocks and 
helps to prevent cracking of the hardened mortar.  
5 Requirements for Mortar  
5.1 General  
The requirements and properties specified in this s tandard shall be defined by the test methods and other 
procedures referred to in this standard. For production evaluation, the manufacturer shall define the 
conformity criteria in the production control documentation . 
5.2 Properties of fresh mortar  
5.2.1  Workable li fe 
In respect of fresh properties, the manufacturer is required to declare the workable life.  
The workable life shall be declared by the manufacturer. When the masonry mortar is sampled from a 
consignment in accordance with RS 211 -2, working life will depe nd upon working characteristics.  
Once the initial set has started the mortar shall not be reconstituted in a mechanical mixer or by any other 
method. Setting of cement is affected by weather and will proceed more slowly when it is colder. This factor is 
taken into account when the mortars are manufactured but subsequent significant reductions in temperature 
may increase the retardation period and extend the working life and will have no adverse effect on the 
masonry.  
The mortar shall be spread easily and re main workable to enable the accurate laying to line and level of the 
masonry units. It shall retain water so that it does not dry out and stiffen too quickly, especially when using 
absorbent masonry units.   
©RSB 2020  - All rights reserved                  8 
 It shall then harden in a reasonable time to preve nt it deforming or squeezing out under the weight of the units 
laid above.  
5.2.2  Workability  
5.2.2.1  Workability may be defined as the behaviour of a mix in respect of all the properties required during 
application, subsequent working and finishing. The operativ e’s opinion of workability is greatly influenced by 
the flow properties of the mix, its cohesiveness and its retention of moisture against the suction of the 
substrate.  
5.2.2. 2 A mortar with good workability shall have the following properties:  
a) ease of use , i.e. the way it adheres or slides on the trowel;  
b) ease of spread on the masonry unit;  
c) ease of extrusion between courses without excessive dropping or smearing; and  
d) ease of positioning of the masonry unit without movement due to its own weight and the weig ht of 
additional courses.  
5.2.2. 2 If a mortar is ‘harsh’, that is of poor workability, the output of craftsmen will be reduced. Picking up 
and spreading will be slower and difficulty will be experienced in placing the cross or perpendicular joints and 
in obtaining a good finish.  
5.2.2. 3 To assess the working properties of the mortar the consistence is first determined in accordance with 
RS 211 -3 or RS 211 -4. 
5.2.3  Chloride content  
When relevant, the chloride content of the mortar as delivered shall be declared by  the manufacturer.  
The chloride content should not exceed 0.1 % Cl of the mortar by dry mass.  
5.2.4  Air content  
When relevant for the use for which the masonry mortar is placed on the market the range in which the air 
content will fall shall be declared by the m anufacturer.  
5.3 Proportion of constituents  
For prescribed mortars the mix proportions by volume or by weight of all the constituents shall be declared by 
the manufacturer. The following is the mix proportion by volume:  
a) cement, 15 %  
b) lime, 10 %  DRS 108: 2020  
9                ©RSB 2020  - All rights reserved  
 c) aggregates, 75 %  
5.4 Properties of hardened mortar  
5.4.1  Compressive strength of mortar for bedding masonry units  
For designed mortars, the compressive strength of masonry mortar shall be declared by the manufacturer.  
Adequate mortar strength is essential, but the final strength of  a mortar should not exceed that of the bricks or 
blocks used.  
The manufacturer may declare the compressive strength class in accordance with Table 1, where the 
compressive strength class is designated by (I), (II), (III), (IV).  
5.4.1.1  Class I  
Reinforced and unre inforced masonry where higher flexural strengths are required.  
5.4.1.2  Class II  
Masonry in contact with earth like normal load bearing applications, as well as parapets, balustrades, retaining 
structures, and freestanding and garden walls, and other walls exposed to possible severe dampness.  
5.4.1.3  Class III  
Lightly stressed non -structural walls.  
5.4.1.4  Class IV  
Non-load bearing application.  
Table 1 — Guide for the selection of mortar  
Location  Building segment  Mortar 
designation  Prescribed mort ar (proportion of 
material by v olum e) Compressive 
strength at 28 
days (N/mm2) 
Cement: Lime: sand  Cement: sand  
Exterior 
above 
grade  Highly stressed masonry 
incorporating high -
strength structural units 
which may be used in 
multi -storey load bearing 
buildings and seismic 
loading  (I) 1:0 to 1/4: 3  1:3 to 4  12  
©RSB 2020  - All rights reserved                  10 
 Exterior at 
or below 
grade  Foundation walls, 
retaining walls, 
manholes, sewers, 
pavement, walks  (II) 1:0 to 1/2: 4  1:5 to 6  6 
Interior  Lightly stressed non -
structural walls  (III) 1:1:5 to 6  1:6 4 
Interior or 
Exterior  Non-bearing p artitions, 
repointing  (IV) 1:2:8 to 9  1:7 2 
 
5.4.2  Compressive strength of rendering/plastering mortar  
5.4.2. 1 The principles for specifying rendering mortars are similar to those for specifying mortars for  bedding 
masonry units. The specification of rendering system requires consideration of a number of parameters:  
a) The nature and condition of the background (its strength and absorptivity); and  
b) The nature and conditions of exposure, the functional requirement, the type of render, the type of  
finish/appearance (t extured/smooth).  
5.4.2. 2 Different fields of use and exposure conditions require mortars with different properties and 
performance levels. For this purpose, compressive strength shall be classified according to Table 2.  The 
properties relevant to the inten ded use and/or type of product shall be declared according to Table 2.  
Rendering is normally subjected to environmental exposure (frost, wind, sun and rain).  
Table 2 — Classification for hardened rendering/plastering mortar  
Intended use of 
mortar  categorie s Mix proportion of materials by volume  
Range of compressive 
strength at 28 days  
Cement: sand: lime  Cement: sand (using 
plasticizer)  
Severe exposure  CSI 1: 1/4: 3  _ > 6 N/mm2  
Moderate exposure  CSII 1: 1/2 4 to 4 1/2  1: 3 to 4  3.5 to 7.5 N/mm2  
Modera tely low 
exposure  CSIII  1:1:5 to 6  1:5 to 6  1.5 to 5.0 N/mm2  
Passive / sheltered 
exposure  CSIV  1:2: 8 to 9  1:7 to 8  0.4 to 2.5 N/mm2  
Note  It is important to consider the mix proportions of mortars with care.  
5.4.2. 3 The location of the structure to which  the rendering has been applied also affects the ability of the  
rendering to withstand the environmental actions applied to it.  
5.4.2.4 The categories of exposure based on driving rain can be described as follows:  
a) Passive/sheltered exposure: these are clas sified as areas of moderately low rainfall in which walls 
are protected from the weather by overhanging eaves and the close proximity of other buildings.  DRS 108: 2020  
11                ©RSB 2020  - All rights reserved  
 b) Moderate exposure: this classification applies to walls partiall y protected from the weather by 
overha nging eaves and by adjacent building of similar height.  
c) Severe exposure: this classification applies to walls which are exposed to the full force of wind and 
rain. 
Examples of this classification would be buildings on hill sites, near the c oast and those p rojecting above 
surrounding buildings.  
5.4.2. 5 The compressive strength class in descending order for hardened rendering/ plastering mortar is  
designated by CSI, CS II, CS III, and CS IV . 
5.4.2. 6 The mix proportions are intended as a guide but  may need alt ering slightly to suit local conditions  
such as the types of brick or block. or the sand being used.  
5.4.3  Bond strength  
Good bond is essential to minimise ingress of water and moisture. The interface of the masonry unit and the 
mortar is usually the most vulner able part of the masonry construction to the ingress of rain. Bond strength is 
required to withstand tensile forces due to wind structural and other applied forces. Movement of the masonry 
units and temperature changes.  
It should also be emphasized that wo rkmanship is a key factor in affecting bond. The time lapse between 
spreading mortar and placing shall be kept to a minimum. Once the masonry unit is in place and aligned it 
shall not be subsequently moved.  
Freshly laid masonry should be protected from ext remes of wind and sun to avoid drying of the mortar before 
hydration of the cement is complete.  
For designed masonry mortars intended to be used in elements subjected to structural requirements the bond 
strength of the mortar in combination with a masonry unit shall be declared in terms of the characteristic initial 
shear strength.  
NOTE  Bond strength depends on the mortar the masonry unit its moisture content and the workmanship.  
5.4.4  Water absorption  
For masonry mortars intended to be used in external elements and exposed directly to the weather, the water 
absorption shall be declared by the manufacturer. When sampled from a consignment in accordance with RS 
211-2 and tested in accordance with RS 211 -7, the water absorption shall not be higher than the declared 
value.  
5.4.5  Density (dry hardened mortar)  
When relevant for the use for which the masonry mortar is placed on the market the range in which the 
density of dry hardened mortar will fall shall be declared by the manufacturer.  
For lightweight masonry mortars the d ensity shall be equal to or less than 1300 kg/m³.   
©RSB 2020  - All rights reserved                  12 
 5.5 Mixing of mortar  
5.5.1  General  
Batching of mortar shall be done by either volume or weight. The manufacturer shall ensure that equipment 
used is calibrated to maintain ac curacy in measurements.  
Where high preci sion is required, measurement by weight is recommended, and by volume otherwise.  
5.5.2  Machine mixing  
Machine mixing refers to mixing large quantities of mortar in a drum -type mixer. All dry ingredients shall be 
placed in the mixer first before adding the water  slowly. The mortar shall be mixed until a completely uniform 
mixture is obtained.  
5.5.3  Hand mixing  
Hand mixing involves mixing small amounts of mortar by hand in a mortar box or wheelbarrow. Care shall be 
taken to mix all ingredients thoroughly to obtain a uni form mixture. As in machine mixing all dry materials shall 
be mixed together first before adding water slowly. A steel drum of water shall be kept close at hand to use as 
the water supply. All masonry tools free of hardened mortar mix and dirt shall be kep t by immersing them in 
water when not in use . 
If certain types of mortar need specific site mixing equipment procedures or times these shall be specified by 
the manufacturer. Mixing time is measured from the time when all constituents have been added.  
6 Desi gnation of masonry mortar manufactured in a plant  
The designation shall include the following as relevant:  
a) name of manufacturer;  
b) a code for or the date of production;  
c) workable life;  
d) chloride content;  
e) air content;  
f) proportion of constituents (for prescribed mortars) and relationship to compressive strength or 
compressive strength class;  
g) compressive strength or compressive strength class (for designed mortars);  
h) bond strength;  DRS 108: 2020  
13                ©RSB 2020  - All rights reserved  
 i) water absorption; and  
j) density.  
NOTE  In the designation for a product information abou t special qualities may be included when the mortar is 
intended for use in special construction.  
7 Marking  
The designation shall be marked on the packaging the delivery ticket or the manufacturer’s data sheet or other  
information accompanying the product.  
8 Evaluation of conformity  
8.1 General  
The manufacturer (or his agent) shall demonstrate compliance for his product with the requirements of this  
Rwanda Standard by carrying out relevant laboratory testing of the mortar.  
8.2 Plant production control  
8.2.1  General  
8.2.1. 1 A plant production control scheme shall be established and documented in a manual. The plant 
production control system shall consist of procedures for internal control of the production to ensure that such 
products placed on the market conform to this standa rd. 
8.2.1. 2 The internal control shall consist of one or both of the following:  
a) regular inspections, checks and tests and the utilization of the results to control equipment. raw or 
incoming materials and the production process; and  
b) regular inspections, ch ecks and tests on the finished product.  
8.2.1. 3 Records shall be maintained of the dates of tests and inspections identification of the products tested 
and the results of the tests or inspections as indicated in the quality manual.  
8.2.2  Process control  
8.2.2. 1 Incoming materials : as appropriate. the manufacturer shall define the acceptance criteria of 
incoming materials and the procedures that he operates to ensure that these are met.  
8.2.2. 2 Production process : as appropriate the relevant features of the plant and production process shall 
be defined giving the frequency of the inspections checks and tests together with the values or criteria 
required both on equipment and on work in progress. The action to be taken when control values or criteria 
are not achieve d shall be given. Weighing and measuring equipment shall be calibrated. The frequency of 
calibration shall be indicated.   
©RSB 2020  - All rights reserved                  14 
 8.2.3  Finished product test  
8.2.3. 1 For testing the finished product. The plant production control system shall incorporate the sampling 
plan and testing frequency of the finished product. The results of sampling and testing shall be recorded.  
8.2.3. 2 Test equipment having a bearing on test results shall be calibrated. The calibration criteria and 
inspection procedures shall be given in the qua lity manual.  
8.2.4  Traceability  
As appropriate, systems of traceability and control of incoming materials and the use of materials shall be 
given in the quality documents. The stock control system of manufactured products shall be given in the 
quality documents.  This should include the method of treating non -conforming products.  
 DRS 108: 2020  
 
Price based on  nnn pages  
©RSB 2020 - All right s reserved