ICS 91.100.01  
 
Reference number  
DRS 514-1: 202 2 
© RSB 2022 
  
 RWANDA 
STANDARD  DRS  
514-1 
 
First edition  
2022-mm-dd 
 
 
Compressed earth blocks —  
Part 1: Definitions, classification  and 
specifications  
   
DRS 514-1: 2022  
©RSB 202 2 - 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 2022 
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  
Tel. +250 788303492  
Toll Free: 3250  
E-mail: info@rsb.gov.rw  
Website: www.rsb.gov.rw  
ePortal: www.portal.rsb.gov.rw   DRS  514-1: 202 2 
iii                ©RSB 2022 - All rights reserved  
 Contents  Page 
1 Scope  ................................ ................................ ................................ ................................ .............  1 
2 Normative references  ................................ ................................ ................................ ...................  1 
3 Terms and definitions  ................................ ................................ ................................ ..................  1 
4 Classification and designation of compressed earth blocks  ................................ ................  13 
5 Classification and designation of compressed earth block masonry  ................................ .. 18 
6 Technical specifications for ordinary compressed earth blocks  ................................ ..........  21 
7 Technical specifications for facing compressed earth blocks  ................................ ..............  25 
8 Technical specifications for ordinary compressed earth block masonry  ............................  30 
9 Technical specifications for facing compressed earth block masonry  ................................  32 
 DRS 514-1: 2022  
©RSB 202 2 - 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 adopted 
by Technical committ ees are ratified  by me mbers of RSB Board of Director s for publication and gazettment as 
Rwanda Standards.  
DRS 514 -1 was prepared by Technical Committee RSB/TC 9, Civil engineering and building materials.  
In the preparat ion of this standard, reference was made to the following standard:  
ARS 670 -1-2014, Compressed earth blocks - Part 1: Definitions, classifications, specifications  
The assistance de rived from the above source is hereby acknowledged with thanks.  
DRS 514  cons ists of the following parts, under the general title Compressed earth blocks : 
⎯ Part 1: Definitions, classifications  and specifications  
⎯ Part 2 Earth mortars  
⎯ Part 3: Test methods  
⎯ Part 4: Code of practice for production and construction  
 
Committee membership  
The following organizations were represented on the Technical Committee on Civil engineering and building 
materials (RSB/TC 9) in the preparation of this standard.  
A+Construction Group Ltd  
Africeramics Ltd  
Consultants Engineers Group (CEG) Ltd 
D&D Resources Ltd  
Dutureheza Ltd  
Enabel Rwanda  DRS  514-1: 202 2 
v                ©RSB 2022 - All rights reserved  
 Greenpack Africa Ltd  
Integrated Polytechnic Regional Centre (IPRC) - Musanze  
Mass Design Group  
NP Construction Construction Company (NPCC) Ltd  
Road Transport Development Agency (RTDA)  
Rwanda Housing Autho rity (RHA)  
Rwanda Inspectorate, Competition and Consumer Protection Authority (RICA)  
Rwanda Quarries Association (RQA)  
SKAT Consult  
St Joseph Engineering Company (SJEC) Ltd  
Standards for Sustainability (SfS)  
Stonecraft Industries Ltd  
University of Rwanda - College of Science and Technology (UR - CST)  
Rwanda Standards Board (RSB) – Secretariat  
 
 
 
 
 
 
 
 DRS 514-1: 2022  
©RSB 202 2 - All rights reserved                  vi 
 Introduction  
The aim of the present standard is to define compressed earth blocks (CEBs)  and compressed earth block 
masonry (CEBM), to classify them according to their typology, appearance and conditions of use, and to 
determine the categories into which they fall as well as their designations.  
The definitions, classifications and designations of  the present standard are applicable in establishing any 
technical, administrative or contractual document relating to compressed earth block technology, and relate to 
both public and private contracts.  
The standard applies exclusively to CEBs and CEBMs intended for the realisation of simple built structures in 
common masonry with thick mortar joints (walls, partitions, piers, small lintels, arches, vaults, domes, etc.) and 
of any similar built structure.  
 DRS 514-1: 202 2 
1                ©RSB 2022 - All rights reserved  
 Compressed earth blocks — Part 1: Definitions, classification  and 
specifications  
1 Scope  
This Draft Rwanda  Standard applies to compressed earth blocks (CEBs) used for the construction of buildings 
for residential, public and related purposes. It gives the definitions of different types of CEBs  and their 
classification. It also provides the requirements and test methods and the conformity criteria of the CEBs 
depending on their intended uses.  
The standard does not apply to CEBs  and CEMBs  used for flooring or tiling, nor to CEBs or CEMBs  designed 
to be assembled dry, interlocking, using glue -mortar, or used in  reinforced masonry.  
The standard is not applicable in areas subject to earthquakes, floods or cyclones to an extent that requires the 
application of appropriate rules in order to avoid major damage.  
2 Normative references  
The following documents are referr ed 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 amendmen ts) applies.  
DRS 546, Clay products for buildings — Vocabulary  
3 Terms and d efinitions  
For the purposes of this standard,  the terms and definitions given in DRS 546  and the following  apply . 
3.1 Terms applicable to compressed earth blocks  
3.1.1  Compressed earth blocks (CEBs)  
Masonry elements, which are small in size and which have regular and verified characteristics obtained by the 
static or dynamic compression of earth in a humid state followed by immediate demoulding.  
Compressed earth blocks generally have a rectangular parallelepiped format and are full or perforated with 
vertical and/or horizontal indentations.  
Compressed earth blocks are principally made of raw earth and owe their cohesion in a humid state and in a 
dry state essentially to the clay fraction  within the earth; an additive can, however, be added to the earth to 
improve or enhance particular characteristics of the product.  
The final characteristics of CEBs depend on the quality of the raw materials used (earth, additive) and on the 
quality of t he execution of the various manufacturing stages (preparation, mixing, compression, curing).   
©RSB 202 2 - All rights reserved                  2 
 NOTE  This definition therefore excludes blocks obtained by extrusion, as well as agglomerated products where the 
chemical binder plays an essential part in ensuri ng cohesion when dry.  
3.1.2  Description  
The most common type of CEB can be described geometrically stating its format. The format of the product 
described consists of its general shape, its principal dimensions and the nature of any indentations (hollows, 
perfo rations etc.) incorporated into the product.  
The most common format is a rectangular parallelepiped (or prismatic) format with a length (l), a width (w) and 
a height (h). Giving these three dimensions in this order (l, w, h) is sufficient for their use.  
Non parallelepiped rectangular formats require a fuller description (cylindrical, conical, hexagonal, wedge -
shaped, in the form of a truncated cone, etc.). The format used for the description is the nominal format which 
takes into account the manufacturing  dimensions.  
The format may be principal or secondary. The principal format or common format corresponds to the basic 
format from which secondary formats are obtained, these being merely fractions or multiples of the basic format 
in relation to its length . The most frequently found secondary formats are the «3/4», the «1/2» and the «1/4» 
the respective lengths of which are:  
a) l 3/4= (l 4/4 - tm/3) ¾ ; 
b) l 1/2= (l 4/4 - tm) ½ ; and  
c) l 1/4= (l 4/4 - 3tm) ¼ . 
where 
 tm is the thickness of the vertical joint.  
There are also CEBs reduced by half in height.  
Secondary format CEBs are required to ensure bonding continuity throughout the built structure, for example at 
wall corners, and at the intersections of walls and partitions.  
Secondary format CEBs are obtained either directly by manufacturing, or cut at the moment of use.  
The «nominal format» should not be confused with the «work format» which corresponds to a description using 
real dimensions to which a correspon ding joint thickness  has been added.  
The work format is therefore a unit of measurement for practical use enabling the dimensions of a built structure 
to be rapidly calculated.  
To recapitulate:  
a) nominal format: (l, w, h)  DRS 514-1: 202 2 
3                ©RSB 2022 - All rights reserved  
 b) work format: (l + tm, w + tm, h + tm)  
 
 
Figure 1 — Example relating to the height of blocks  
The nominal format is the one normally used and in the event of any danger of confusion it is recommended 
that the nature of the format being used should be specified.  
3.1.3  Description of the parts of CEBs  
The prismatic block has 6 faces, each of which has a name:  
a) 2 faces are known as surface «stretchers» (l × h);  
b) 2 faces are known as surface «headers» (w × h);  
c) 1 face is known as the «laying face» (l × w), being the upper fac e of the CEB when laid;  
d) 1 face is known as the «bed face» (l × w), being the lower face of the CEB when laid.  
 
 
©RSB 202 2 - All rights reserved                  4 
  
Figure  2 — CEB faces  
The details describing a CEB should include the following values:  
a) gross section: l × w (l and w measured on the same plane);  
b) net section: gross section less any hollow;  
c) bed section: surface common to the laying and the bed faces when superimposed in conta ct with the mortar 
joints and capable of transmitting the load.  
 
Figure 3 — CEB sections  
 
DRS 514-1: 202 2 
5                ©RSB 2022 - All rights reserved  
 3.2 Terms applicable to compressed earth block production and production equipment  
3.2.1  Terms applicable to CEB constituents  
3.2.1.1  Earth  
Earth intended for CEB construction designates the basic material made up essentially and in carefully 
controlled proportions of the following components, before any mixing with an additive or with water: gravel, 
sand, silt and clay. These components can b e defined using a metric classification, or with regard to the fines, 
by their mineralogical nature.  
The metric classification  shall be as per  Table 1 .  
Table 1 — Metric classification  
Classification  Component   Size 
gravel fraction:  coarse gravel  -  60 mm to 20 mm;  
medium gravel  -  20 mm to 6 mm;  
fine gravel  -  6 mm to 2 mm;  
sand fraction:  coarse sand  -  2 mm to 0.6 mm;  
medium sand  -  0.6 mm to 0.2 mm;  
fine sand  -  0.2 mm to 0.06 mm;  
silt fraction:  coarse silt  -  0.06 mm to 0.02 mm;  
medium silt  -  0.02 mm to 0.006 mm;  
fine silt  -  0.006 mm to 0.002 mm;   
©RSB 202 2 - All rights reserved                  6 
 clay fraction:  passes the  -  0.002 mm sieve.   
There are other classifications which are also acceptable.   
Coarse material (gravel and part of the sand fraction) consists of components with a diameter in excess of 0.08 
mm. Coarse material provides the stable "skeleton" of CEBs thanks to its internal friction and its inertia.  
Fine material (a part of the fine sand fra ction, silt and clay) consists of components  with the diameter of which 
is less than or equal to 0.08 mm. From a mineralogical point of view, the notions of clay and of silt are not 
restricted to the metric values given above. Understanding the mineralogic al nature of fines may be vital when 
selecting types of earth.  
Fines fill in the voids in the "skeleton". Clay and part of the silt fraction provide the cohesion of CEBs because 
they act as binders.  
3.2.1.2  Additive  
An additive is a substance added during manufa cture, intended to improve the final characteristics of the CEB 
or to enhance particular characteristics.  
The most common additives are stabilisation products, know n as stabilisers, such as cement, lime, pozzolonas, 
etc. intended to neutralise the sensiti vity to water of the fine fraction and thus to maintain cohesion at an 
acceptable level even in a humid state. But other additives can also be used to modify other characteristics 
such as colour (colouring agents), tensile strength and reducing shrinkage c racks (fibres), etc.  
3.2.1.3  Filler  
A filler is a granular material, generally of a sandy type, employed as an additive in types of earth which contain 
too great or too active a silt and/or clay fraction.  
3.2.1.4  Mix 
The mix is the material obtained by adding additives and/or filler and water to the earth, preparatory to being 
introduced into the press for the manufacture of the CEB.  
3.2.2  Terms applicable to the production of compressed earth blocks  
3.2.2.1  Preparing the earth  
This consists of the following operations:  
a) drying;  
b) screening ; and  DRS 514-1: 202 2 
7                ©RSB 2022 - All rights reserved  
 c) pulverising . 
3.2.2.1.1  Screening  
This operation is intended to eliminate all undesirable components (roots, leaves, any other organic 
material…etc.) together with any components with a diameter greater or lesser than that required. This operation 
also enables the earth to be loosened in a uniform manner.   
3.2.2.1.2  Pulverising  
This operation is intended to break down lumps made up of coarse material and/or fines. It can also be used to 
split coars e material to reduce it to smaller diameter aggregates.  
3.2.2.2  Mixing  
This is a series of technical operations aimed at making the prepared earth, homogeneous.to which additives 
and/or a filler may have been added, homogeneous. Mixing most often takes place in t wo stages: dry mixing 
before adding water and wet mixing after adding water. There may also be a third stage, after a given reaction 
time, which consists in subjecting the mix to a further phase of stirring.   
3.2.2.3  Retention time  
Retention time is the delay betw een the start of wet mixing and the compression of the earth.  
3.2.2.4  Compression  
Compression is the operation which consists in compressing the material in a confined space known as a mould 
using a static or dynamic mode; compression is followed by immediate dem oulding, freeing the shaped block.  
3.2.2.5  Curing  
Curing is the period following compression during which two types of phenomena principally occur. These can 
be differentiated as follows:  
a) physicochemical reactions between the various components of the mix and above all between the earth 
and the additives  resulting in the stabilisation of the block; during this phase, conditions of relative 
hygrometry and of heat are crucial and require careful attention;  
b) drying which consists in the gradual removal of manufacturing humidity by evaporation.  
3.2.3  Terms applicab le to production equipment  
3.2.3.1  Preliminary note  
All production operations can be carried out manually with simple tools or using manual or motorised mechanical 
equipment.   
©RSB 202 2 - All rights reserved                  8 
  
3.2.3.2  Earth preparation equipment  
Preparation equipment includes:  
a) screens, to remove compone nts with too large a diameter ; and  
b) pulverisers, which allow the particle size of coarse components to be reduced or silt and clay aggregates to 
be broken down without affecting the particle size distribution.  
3.2.3.3  Mixing equipment  
Mixing is carried out using a mixer. Mixers can be planetary, where the mixing system is mounted on a vertical 
axis, or linear, where the mixing system is driven by a horizontal axis.  
3.2.3.4  Presses  
Presses are classified using several criteria:  
a) the energy sour ce: manual or motorised (with a distinction between thermal and electric motors);  
b) the system by which the energy is transmitted to the moulding system: mechanical, hydraulic, or combined.  
3.2.3.5  Specific characteristics of presses  
In describing presses, certain specific criteria are used.  
a) Compression action:  this is the very principle of the operation of the compression system. Compression 
may be static, dynamic by vibration or dynamic by impact ; 
b) Usable force:  the force potentially available to compact the earth ; and   
c) Compression pressure:  the pressure theoretically applied to the mix and which expresses the ratio of 
usable force to the surface to which it is applied; compression pressure is classified as Table  2. 
Table 2 — Classification of compression pressure  
- very low pressure:  1 to 2 N/mm2;  
- low pressure:  2 to 4 N/mm2;  DRS 514-1: 202 2 
9                ©RSB 2022 - All rights reserved  
 - medium pressure:  4 to 6 N/mm2;  
- high pressure:  6 to 10 N/mm2;  
- hyperpressure:  10 to 20 N/mm2;  
- megapressure  20 N/mm2 and over.   
NOTE  It should be noted that the highest compression pressures are not necessarily the most efficient.   
d) Pressure at the end of compression:  the pressure actually applied to the mix at the end of compression.  
e) Dynamic effect coefficient:  the effect, on static compression presses, due to the inertia of the lever 
movement of the machine, which increases the pressure at the end of compression.  
f) Compression mode:  the principle of spreading the pressure across the mix. In simple compression, 
pressure is transmitted by displacing a single plate onto the laying or the bed face. In double compression, 
pressure is applied by displacing both plates onto the laying and the bed face simultaneously or 
alternatively.  
g) Compression ratio:  the ratio between the depth of the press mould before compression and the depth at 
the end of compression (which corresponds to the height of the CEB product).  
h) Output:  theore tical output corresponds to the sum of the number of CEBs produced per cycle, by number 
of cycles (filling, compression, demoulding) per hour; practical output corresponds to the theoretical output 
adjusted for estimated down time (machine maintenance etc. ); actual output is the output measured in the 
context of normal activity.  
3.2.4  Terms applicable to delivery conditions  
3.2.4.1  Order  
3.2.4.1.1  Ordering earth  
The order specifies the designation of the earth (gravely earth, sandy earth, clayey earth, etc.), the quantity, the 
place of delivery, and the procedure for accepting or rejecting delivery. The order may also specify the location 
of the quarry and the dep th of the quarrying operation.  
3.2.4.1.2  Order for CEBs  
The order specifies the designation of the CEBs, the quantity, the delivery location, and the procedure for 
accepting or rejecting delivery.   
©RSB 202 2 - All rights reserved                  10 
 3.2.4.2  Supply  
The quantity of merchandise corresponding to one and the sam e order.  
3.2.4.3  Delivery  
The quantity of merchandise delivered or intended to be delivered on one single occasion, whatever the number 
and the nature of the means of transport used.  
3.2.4.4  Lot 
The quantity of merchandise serving as a basis for determining samples for testing.  
3.2.4.5  Taking delivery  
A series of operations enabling the conformity of the merchandise to be checked against the specifications of 
the standard.  
3.3 Terms applicable to construction with CEBs  
Compressed earth blocks being masonry elements, when referring  to their use, one therefore applies the 
common terminology of traditional masonry with thick mortar joints (around 15 mm).  
3.3.1  Earth mortar  
An earth mortar (EM) is a mortar used for compressed earth block masonry of a traditional type using thick 
mortar join ts.  
An earth mortar consists principally of raw earth and water and owes its cohesion in a humid or a dry state 
essentially to the clay fraction of the earth; an additive and/or a filler can, however, be added to the earth to 
improve or enhance particular char acteristics of the mortar.  
3.3.2  Compressed earth block masonry  
Compressed earth block masonry (CEBM) is masonry of a traditional type using thick earth mortar joints.  
3.4 Terms applicable to assessing the characteristics, performance and suitability for use of 
CEBs  
To assess the characteristics, performance and suitability for use of compressed earth blocks, one should use 
the terminology commonly used for other small masonry elements, excluding the elements provided in the 
present standard relating to terminology.  DRS 514-1: 202 2 
11                ©RSB 2022 - All rights reserved  
 3.5 Symbols and units  
3.5.1  Units of measurements  
Table 3 — Symbols and basic units of measurement  
Symbols  English   French   SI Units   Units used in the 
building sector  
L  Length  Longueur  metre  m m, cm, mm  
F  Force  Force  newton  N MN, kN, N  
 Pressure, 
Stress  Pression, Contrainte  pascal  N/m2 MPa=N/mm2=MN/m2 
m  Mass  Masse  kilogramme  Kg t, kg, g  
t  Temperature  Temprature  degrees 
Celsius  °C °C  
T  Time  Temps  seconds  s h, min, s  
 
3.5.2  General notations  
Table  4 — Symbols and units of general notations  
Symbol  English  French  Formula  Unit 
Ph  Humid weight  Poids humide   
g, kg  
Pd  Dry weight  Poids sec   
g, kg  
Pw  Weight of water  Poids d'eau   
g, kg  
V  Volume of sample  Volume de l'échantillon   
cm3, m3  
W  Water content  Teneur en eau  
Pd100 PwW= % 
weight  
Wopt  Optimum water content  Teneur en eau optimale   
% 
weight   
©RSB 202 2 - All rights reserved                  12 
 Symbol  English  French  Formula  Unit 
d Dry density  Masse volumique séche (Densité 
séche)  
W)(1VPh
d+= kN/m3  
h Apparent density  Masse volumique apparente 
(Densité apparente)  
VPh
h= kN/m3  
s Solid grains density  Masse volumique des grains 
solides (Densité des grains solides)  s = 26.5  kN/m3  
Pstab  Weight of binder  Poids de liant   
g, kg  
Stab  Binder content  Teneur en liant 
Pd100 PSstab
stab=
 % 
weight  
D  Largest grain diameter  Diamétre du plus gros grains   
mm  
0/d  Grain fraction between 0 
and d mm  Fraction granulométrique entre 0 et 
d mm    
LL  Liquid limit  Limite de liquidité   
% 
weight  
PL  Plastic limit  Limite de plasticité   
% 
weight  
IP Plasticity index  Indice de plasticité  Ip = LL - PL   
VBS(0/d)  Methylene blue value of the 
0/d fraction of soil  Valeur de bleu de méthylène de la 
fraction 0/d du sol    
VBS total  Methylene blue value of the 
entire soil Valeur de bleu de méthylène totale 
du sol    
l  Length of CEB  Longueur du BTC   
mm, cm  
w  Width of CEB  Largeur du BTC   
mm, cm  
h  Height of CEB  Hauteur du BTC   
mm, cm  
tm  Thickness of mortar  Epaisseur du mortier   
mm, cm  
fb dry Dry compressive strength 
of CEB tested in 
homogeneous conditions  Résistance à la compression sec 
du BTC teste dans des conditions 
homognes   
N/mm2  
t
bf
dry Dry tensile strength of CEB  Résistance à la traction sec du BTC   
N/mm2  
fb wet Wet compressive strength 
of CEB  Résistance à la compression 
humide du BTC   
N/mm2  
t
bf
wet Wet tensile strength of 
CEB Résistance à la traction humide du 
BTC  
N/mm2  
fm dry Dry compressive strength 
of mortar  Résistance à la compression sec 
du mortier   
N/mm2  DRS 514-1: 202 2 
13                ©RSB 2022 - All rights reserved  
 Symbol  English  French  Formula  Unit 
t
mf
dry Dry tensile strength of 
mortar  Résistance à la traction sec du 
mortier   
N/mm2  
Eb  Young's modulus of CEB  Module d'Young du BTC   
N/mm2  
Vb  Poisson's ratio of CEB  Coefficient de Poisson du BTC   
Em  Young's modulus of EM  Module d'Young du MT   
N/mm2  
Vm  Poisson's ratio of EM  Coefficient de Poisson du MT    
hef  Effective height of wall  Hauteur effective du mur   
cm, m  
t  Thickness of wall  Epaisseur du mur   
cm, m  
fk  Dry characteristic 
compressive strength of 
masonry  Résistance nominale la 
compression sec de la maçonnerie   
N/mm2  
fvk  Dry characteristic shear 
strength of masonry  Résistance au cisaillement sec de 
la maçonnerie   
N/mm2  
fvko  Dry characteristic shear 
strength of masonry at zero 
precompression  Résistance au cisaillement sec de 
la maçonnerie sans 
précompression   
N/mm2  
 
4 Classification and designation of compressed earth blocks  
4.1 Classification of CEBs  
4.1.1  Classification of CEBs by type 
Compressed earth blocks are classified according to several types.  
4.1.1.1  CEB type 1  
Full rectangular parallelepiped format with no indentation on any face.  
4.1.1.2  CEB type 2  
Full rectangular parallelepiped format with an indentation on one or both of its larger faces (laying and bed face). 
Various common indentations include:  
a) hollows (frogs), which makes the CEB lighter and easier to handle;  
b) slight horizontal grooves allowing a better bond with the mortar;   
©RSB 202 2 - All rights reserved                  14 
 c) horizontal grooves to receive thin construction elements, such as pipes, electric cables etc.;  
d) deep horizontal grooves to receive construction elements such as ring beams etc.;  and 
e) lateral grooves enabling claustra -work structures to be built without needing to use special bonding.  
4.1.1.3  CEB type  3 
Full rectangular parallelepiped format with one or more indentations (e.g. hollows, rounded or chamfered 
corners, etc.) on the stretcher or header faces or simultaneously on several faces.  
Indentations in the vertical (header or stretcher) faces of CEBs are most often grooves intended to receive thin 
construction elements.  
4.1.1.4  CEB type 4  
Rectangular parallelepiped format with holes or perforations between the largest faces. Depending on the 
section of the holes and on how many there are, one refers to perforated blocks (a few, small holes), hollow 
blocks (a few, large holes) or alveolar blocks (many small perforations).  
4.1.1.5  CEB type 5  
Rectangular parallelepiped format with holes or perforations in combination with indentations on its larger faces 
(laying face and bed face).  
4.1.1.6  CEB type 6  
Rectangular parallelepiped format with holes or perforations and with indentations on the stretcher and header 
faces sometimes in combination with indentations on its  larger faces.  DRS 514-1: 202 2 
15                ©RSB 2022 - All rights reserved  
  
Figure  4 — The 6 types of CEB  
 
4.1.2  Classification according to use  
CEBs can be classified into two groups according to use:  
 
©RSB 202 2 - All rights reserved                  16 
 a) ordinary CEBs;  
b) facing CEBs.  
4.1.2.1  Ordinary CEBs (CEB O)  
These are CEBs used in masonry structures intended to be covered by some form of protection.  
4.1.2.2  Facing CEBs (CEB F)  
These are CEBs used in masonry structures intended to remain visible. One can differentiate between:  
a) normal facing CEBs (CEB NF);  and 
b) fine facing CEBs (CEB FF).  
The difference between these two facing CEBs is restricted to their appearance without affecting their other 
characteristics.  
4.1.2.3  Classification according to field of use  
The fields of use of CEBs within masonry structures are class ified according to two types of constraints which 
can occur simultaneously:  
a) mechanical constraints;  and  
b) environmental constraints.  
4.1.2.4  Mechanical constraints  
These are defined according to three categories of resistance:  
a) category 1:  structural elements whic h are not load -bearing and structural elements capable of withstanding 
limited external (live) loads : for example — fill-in in a load -bearing structure ; boundary wall ; a single -storey 
building made of load -bearing structural elements ;  
b) category 2:  structural elements capable of withstanding important external (live) loads : for example — a 
two storey building with accessible terrace made of thin load -bearing structural elements ; and  
c) category 3:  structural elements capable of withstanding high extern al (live) loads : for example — a three 
storey public building made of thin load -bearing structural elements.  
4.1.2.5  Environmental constraints  
These are defined according to 4 categories of environment:  DRS 514-1: 202 2 
17                ©RSB 2022 - All rights reserved  
 a) category D:  structural elements located in a dry environment  with no danger of being wet : e.g. internal 
partitions ; external walls which are not exposed or which are protected from water damage ; 
b) category R:  structural elements capable of withstanding water damage by lateral spraying : e.g. lateral walls 
exposed to r ain; bathroom walls being splashed ; 
c) category C:  structural elements capable of withstanding water damage by vertical penetration (capillary 
rise, penetration by gravity, suction or internal condensation) : e.g. external walls unprotected from capillary 
rise; internal walls unprotected from water leaking through the roof ; and  
d) category A:  structural elements capable of withstanding mechanical abrasion (impact, rubbing or wind 
damage) : e.g. corners or walls subject to impact ; areas subject to rubbing by animals ; areas subject to sand 
storms.  
4.2 Designation of CEBs  
The designation of compressed earth blocks includes the following indications, to be given in the same order:  
a) product designation  
CEB for «compressed earth block»;  
b) designation according to use:  
O for «ordinary»  
F for «facing»  
NF for «normal facing»  
FF for «fine facing»;  
c) designation according to mechanical constraints:  
1 for «category 1»  
2 for «category 2»  
3 for «category 3»;  
d) designation according to the constraints of the hygrometric environment:  
D for «category D»  
R for «category R»   
©RSB 202 2 - All rights reserved                  18 
 C for «category C»;  
e) designation according to the constraints of the mechanical abrasion environment:  
A for «category A».  
The CEB designation may also include the following indications to be given in the same order:  
a) type of CEB;  
b) manufacturer's trade name or mar k; 
c) the manufacturing dimensions (L, w, h);  
d) colour;  
e) any other feature which helps to identify the CEBs.  
Table 5 — Examples of designation  
Designation  Description   Example   
CEB O 1 D  Ordinary compressed earth block used as an 
element in a non -load bearing structure in a dry 
environment not subject to mechanical abrasion  Internal partition of a single  
family ground floor house  
CEB FF 3 RA  Fine facing compressed earth block used as an  
element in a load -bearing structure exposed to 
rain weathering by lateral spraying as well as to 
mechanical abrasion  External wall of a 3 -storey 
building of high  quality 
appearance exposed to driving 
rain and to sand storms  
5 Classification and designati on of compressed earth block masonry  
5.1 Classification of CEBM  
5.1.1  Classification according to use  
CEBMs can be classified into two groups according to use:  
a) ordinary CEBMs;  and 
b) facing CEBMs.  DRS 514-1: 202 2 
19                ©RSB 2022 - All rights reserved  
 5.1.1.1  Ordinary CEBM (CEBM O)  
These are CEBMs used in structures intended to be covered by some form of protection. They are assembled 
using ordinary CEBs and ordinary EMs.  
5.1.1.2  Facing CEBM (CEBM F)  
These are CEBMs used in structures intended to remain visible. They are assembled using fac ing CEBs and 
facing EMs. One can differentiate between:  
a) normal facing CEBMs (CEBM NF) assembled using CEB NF and EM NF;  
b) fine facing CEBMs (CEBM FF) assembled using CEB FF and EM FF.  
The difference between these two facing CEBMs is restricted to their appe arance without affecting their other 
characteristics.  
5.1.2  Classification according to field of use  
The fields of use of CEBMs within masonry structures are classified according to two types of constraint which 
can occur simultaneously:  
a) mechanical constraints ; and 
b) environmental constraints  
5.1.2.1  Mechanical constraints  
These are defined according to three categories of resistance:  
a) category 1:  structural elements which are not load -bearing and structural elements capable of withstanding 
limited external (live) loads : e.g. fill -in in a load -bearing structure ; boundary wall ; a single -storey building 
made of load -bearing structural elements);  
b) category 2:  structural elements capable of withstanding important external (live) loads : for example,  a two 
storey building with accessible terrace made of thin load -bearing structural elements) ; and   
c) category 3:  structural elements capable of withstanding high exte rnal (live) loads : e.g. a three storey public 
building made of thin load -bearing structural elements.  
5.1.2.2  Environmental constraints  
These are defined by 4 categories of environment:  
a) category D:  structural elements located in a dry environment with no danger of being wet: e.g. internal 
partitions; external walls which are not exposed or which are protected from water damage ;  
©RSB 202 2 - All rights reserved                  20 
 b) category R:  structural elements capable of withstanding water damage by lateral spraying: e.g. lateral walls 
exposed to rain; bathroom walls being splashed ; 
c) category C:  structural elements capable of withstanding water damage by vertical penetration (capillary 
rise, penetration by gravity, suction or internal condensation): e. g. external walls unprotected from capillary 
rise; internal walls unprotected from water leaking through the roof ; and 
d) category A:  structural elements capable of withstanding mechanical abrasion (impact, rubbing or wind 
damage): e.g. corners or walls subje ct to impact; areas subject to rubbing by animals; areas subject to sand 
storms.  
5.2 Designation of forms of CEBM  
The designation of forms of compressed earth block masonry includes the following indications, to be given in 
the same order:  
a) product designation:  
CEBM for «compressed earth block masonry»;  
b) designation according to use:  
O for «ordinary»  
F for «facing»  
NF for «normal facing»  
FF for «fine facing»;  
c) designation according to mechanical constraints:  
1 for «category 1»  
2 for «category 2»  
3 for «category 3»;  
d) designation according to the constraints of the hygrometric environment:  
D for «category D» 
R for «category R»  
C for «category C»;  DRS 514-1: 202 2 
21                ©RSB 2022 - All rights reserved  
 e) designation according to the constraints of the mechanical abrasion environment:  
A for «category A».  
The CEBM designation may also include the following indications to be given in the same order:  
a) type: load bearing or non -load bearing;  
b) colour;  
c) decorative effects;  
d) any other feature which helps to identify CEBM.  
Table  6 — Examples of designation  
Designatio n  Description   Example   
CEBM O 1 D  Ordinary compressed earth block masonry 
used as a component of a non -load bearing 
structure in a dry environment not subject to 
mechanical abrasion  Internal partition of a single family 
ground floor house  
CEBM FF 3 RA  Facing compressed earth block masonry used 
as a component in a load -bearing structure 
exposed to rain weathering by lateral 
sprinkling as well as to mechanical abrasion  External wall of a 3 -storey 
building of high  quality 
appearance exposed to driving 
rain and to sand storms  
6 Technical specifications for ordinary compressed earth blocks  
6.1 Textural characteristics  
The earth should not contain any particles with a diameter greater than 10 mm. To obtain an optimal result, the 
diameter of the largest particles will be restricted to 5 mm.  
6.2 Dimensional characteristics  
6.2.1  Dimensions  
The most commonly employed full compressed earth blocks have the following theoretical moulding dimensions 
and nominal dimensions:  
a) length: 29.50 cm;   
©RSB 202 2 - All rights reserved                  22 
 b) width: 14.00 cm;  and 
c) height: 9.00 cm to 9.50 cm.  
These blocks are used as a reference here for the terms of the specifications which follow. For CEBs of different 
dimensions, tolerances should be adjusted using a linear mathematical relationship.  
The measurements given are th e net block dimensions, not counting any hollows or indentations.  
Special blocks can be developed using other main formats. Dimensional tolerances are as follows:  
a) length: + 2 to - 3 mm;  
b) width: + 2 to - 3 mm;  and 
c) height: + 3 to - 3 mm.  
In addition, the di fference between the corresponding dimension of two CEBs of any kind from the same supply 
must not exceed 4 mm for the length, 3 mm for the width and 5 mm for the height.  
6.2.2  Thickness of sides of indented or hollow blocks  
For all faces: minimum 25 mm or 3 ti mes the diameter of the largest particle if the diameter of the largest particle 
exceeds 8 mm.  
6.3 Geometric characteristics  
6.3.1  Irregular geometry  
CEBs which have a deliberately irregular geometrical form are not subject to the specifications of this article. 
However, the flatness of the bed faces must meet the conditions which follow.  
6.3.2  Parallelism  
Defects of parallelism or of right angles, and also the acceptable sweep of a face, cannot exceed the tolerance 
for the dimension affected.  
6.3.3  Surface smoothness  
a) Sides: the sweep must not exceed 2 mm ; and  
b) Compression surfaces: the sweep must not exceed 3 mm.  
6.3.4  Edge smoothness  
a) The sweep must not exceed 3 mm.  DRS 514-1: 202 2 
23                ©RSB 2022 - All rights reserved  
 b) Some roughness on the edges can be tolerated, whether it is due to demoulding or caused by mishandling.  
6.3.5  Surface obliquity  
a) For exterior faces, form and dimensional tolerances must be respected.  
b) Interior faces and the hollows of hollow or indented blocks must be oblique and must have no sharp corners.  
6.4 Appearance characteristics  
6.4.1  Damage  
A distinction is made between mechanical damage caused by impact when handling CEBs and cracks or other 
defects which result from an imperfect production process.  
For cracks and other manufacturing defects, the prescriptions which follow are applicable.  
For mechanical damage, the following rule is to be respected: damage which has no effect on the appearance 
of the masonry (such as chips on the side of the CEB which is not visible) will not be taken into account.  
The following are regarded as damaged:  
a) any broken CEB;  
b) any CEB displaying chipped edges or corners the overall volume of which exceed 5% of the volume of the 
CEB.  
6.4.2  General appearance  
The CEBs should display no systematic defects such as cracks or significant chips of a kind likely to jeopardise 
correct execution and the stability of the masonry.  
6.4.3  Holes, punctures and scratches  
For exposed faces, these must affect no more than 20% of the surface and not exceed 5 mm in depth.  
6.4.4  Roughness  
The exposed faces can have a grainy and rough appearance.  
6.4.5  Chip ped corners  
Chipped corners and edges which do not extend over more than 10 mm and which do not exceed 10 mm in 
depth  are tolerated on all surfaces.   
©RSB 202 2 - All rights reserved                  24 
 6.4.6  Flaking, splitting  
These are tolerated provided mechanical performance is not affected.  
6.4.7  Cracks, crazing, fissures  
a) Micro -cracks: are tolerated on all faces.  
b) Macro -cracks: Conditions of acceptability for all faces:  
1) they must not exceed 1 mm in width;  
2) they must not exceed 40 mm in length;  
3) they must not exceed 10 mm in depth;  
4) they must not exceed 3 in number on any one surface.  
6.5 Physicochemical characteristics  
6.5.1  Pitting  
No pitting due to the bursting of expansive materials is tolerated.  
6.5.2  Efflorescence  
CEBs must not display any significant and lasting efflorescence covering more than 1/3  of the total surfac e of 
the CEBs. A faint whitish film or a thin band are not taken into account.  
6.6 Mechanical, hygrometric and physical characteristics  
Mechanical, hygrometric and physical characteristics are determined by the values shown in the following table.  
Table 7 — Mechanical, hygrometric and physical characteristics required for ordinary CEBs  
Designation  Environmental 
constraint 
category  Mechanical 
constraint 
category  fb dry 
N/mm2 fb wet 
N/mm2 Water 
absorption 
% Abrasion 
Loss of 
matter %  
CEB O 1 D  Dry 
environment  
(D) 1 2 N/A N/A N/A 
CEB O 2 D  2 4 N/A N/A N/A DRS 514-1: 202 2 
25                ©RSB 2022 - All rights reserved  
 CEB O 3 D  3 6 N/A N/A N/A 
CEB O 1 R  Effect of water 
by 
lateral spraying  
(R) 1 2 1 N/A N/A 
CEB O 2 R  2 4 2 N/A N/A 
CEB O 3 R  3 6 3 N/A N/A 
CEB O 1 C  Effect of water  
by vertical  
penetration (C)  1 2 1 ≤15 N/A 
CEB O 2 C  2 4 2 ≤10 N/A 
CEB O 3 C  3 6 3 ≤5 N/A 
1) N/A = not applicable  
2) The use of CEBs in R and C category environments requires using a stabiliser if the protection provided is not 
guaranteed. If the protection provided against water damage is guaranteed, the environment is regarded as category D.  
3) If tests to establish water absorption or abrasion are not feasible, or if the results are not available, this deficiency can 
be compen sated by increasing the requirements for the dry and/or wet compressive strength by one category.  
4) The values given are the average values obtained from tests carried out on a set of samples.  
7 Technical specifications for facing compressed earth blocks  
7.1 Textural characteristics  
The earth should preferably not contain any particles with a diameter greater than 10 mm. To obtain an optimal 
result, the diameter of the largest particles will be restricted to 5 mm.  
7.2 Dimensional characteristics  
7.2.1  Dimensions  
The most commonly employed full compressed earth blocks have the following theoretical moulding dimensions 
and nominal dimensions:   
©RSB 202 2 - All rights reserved                  26 
 a) length: 29.50 cm;  
b) width: 14.00 cm;  and 
c) height: 9.00 cm to 9.50 cm.  
These blocks are used as a reference here for the terms of the specifications which follow. For CEBs of different 
dimensions, tolerances should be adjusted using a linear mathematical relationship.  
The measurements given are the net block dimensions, not counting any hollows or indentations.  
Special blocks can be developed using other main formats. Dimensional tolerances are as follows:  
a) length: + 1 to - 3 mm;  
b) width: + 1 to - 2 mm;  and 
c) height: + 2 to - 2 mm.  
In addition, the difference between the corresponding dimension of two CEBs of any kind from the same supply 
must not exceed 3 mm for the length, 2 mm for the width and 3 mm for the height.  
7.2.2  Thickness of sides of indented or hollow blocks  
For all faces: mi nimum 25 mm or 3 times the diameter of the largest particle if the diameter of the largest particle 
exceeds 8 mm.  
7.3 Geometric characteristics  
7.3.1  Irregular geometry  
CEBs which have a deliberately irregular geometrical form are not subject to the specifications of this article. 
However, the flatness of the bed faces must meet the conditions which follow.  
7.3.2  Parallelism  
Defects of parallelism or of right angles, and also the acceptable sweep of a face, cannot exceed half the 
tolerance for the dimension affected.  
7.3.3  Surface smoothness  
a) Sides: the sweep must not exceed 1 mm.  
b) Compression surfaces: the sweep must not exceed 3 mm.  DRS 514-1: 202 2 
27                ©RSB 2022 - All rights reserved  
 7.3.4  Edge smoothness  
a) The sweep must not exceed 2 mm ; and  
b) Some roughness on the edges can be tolerated, provided this is due to demoulding and not cause d by 
mishandling.  
7.3.5  Surface obliquity  
a) For exterior faces, form and dimensional tolerances must be respected.  
b) Interior faces and the hollows of hollow or indented blocks must be oblique and must have no sharp corners.  
7.4 Appearance characteristics  
These characte ristics are common to both NF and FF blocks except where specific indications are given.  
7.4.1  Damage  
A distinction is made between mechanical damage caused by impact when handling CEBs and cracks or other 
defects which result from an imperfect production process.  
For cracks and other manufacturing defects, the prescriptions which follow are applicable.  
For mechanical damage, the following rule is to be respected: damage which has no effect on the appearance 
of the masonry (such as chips on the side of the CEB which is not visible) will not be taken into account.  
The following are regarded as damaged:  
a) any broken CEB;  
b) any CEB displaying chipped edges or corners the overall volume of which exceed 2% of the volume of the 
CEB.  
7.4.2  General appearance  
The CEBs should display no systematic defects such as cracks or significant chips of a kind likely to jeopardise 
correct execution and the stability of the masonry.  
90% of facing compressed earth blocks should not display on the faces intended to remain visible, any cracks, 
chips or efflorescence compromising the appearance of the built structure required, visible at  a distance of two 
metres.   
©RSB 202 2 - All rights reserved                  28 
 7.4.3  Holes, punctures and scratches  
For exposed faces in the NF category, these must affect no more than 10% of the surface and not exceed 2 
mm in depth.  
For exposed faces in the FF category, these must affect no more than 2.5% of t he surface and not exceed 1 
mm in depth.  
7.4.4  Roughness  
The exposed faces can be rough for the NF category, must be smooth for the FF category, other than when a 
particular effect is being sought by the client.  
7.4.5  Chipped corners  
Chipped corners and edges which do not extend over more than 10 mm and which do not exceed 10 mm in 
depth are tolerated on all surfaces.  
7.4.6  Flaking, splitting  
These are not tolerated on any surface.  
7.4.7  Cracks  
a) micro-cracks: can be tolerated on all faces ; 
b) macro-cracks: Conditions of acceptabil ity for all faces:  
1) they must not exceed 0.5 mm in width;  
2) they must not exceed 20 mm in length;  
3) they must not exceed 5 mm in depth;  
4) they must not exceed 2 in number for NF category CEBs, 1 in number for FF category CEBs, on any 
one surface.  
7.4.8  Colour  
This can be:  
a) uniform colour: all the facing CEBs of the lot have the same basic colour on all visible faces ; and  
b) varied colour: facing CEBs from the same lot have different shades of colour as defined by the client.  DRS 514-1: 202 2 
29                ©RSB 2022 - All rights reserved  
 7.4.9  Structure  
CEBs must have a uniform and homogeneous structure.  
Depending on the structure, the following main indications of the surface of materials can be distinguished:  
a) smooth: a closed structure surface for which the voids between grains have been completely fi lled; any 
hollows are superficial and spread evenly over the surface ; and   
b) granulated: a surface with a practically closed surface, characterised by the calibre of the grains and by the 
voids spread evenly between these particles.  
7.4.10  Surface texture  
The surfa ce of CEBs has a homogeneous texture. The following indications of the surface texture depending 
on their particular treatment, mechanical or not, can be distinguished: flat, split, grooved, streaked, etc. This list 
is not restrictive.  
7.5 Physicochemical cha racteristics  
7.5.1  Pitting  
No pitting due to the bursting of expansive materials is tolerated.  
7.5.2  Efflorescence  
CEBs must not display any significant and lasting efflorescence covering more than 1/4 of the total surface of 
the CEBs. A faint whitish film or a thin band are not taken into account.  
7.6 Mechanical, hygrometric and physical characteristics  
Mechanical, hygrometric and physical characteristics are determined by the values shown in the following table.  
Table 8 — Mechanical, hygrometric and physical character istics required for facing CEBs  
Designation   Environmental 
constraint 
category  Mechanical 
constraint 
category  fb dry 
N/mm2 fb wet 
N/mm2 Water 
absorption 
% Abrasion 
Loss of 
matter %  
CEB NF 1 D or CEB FF 1 D  Dry 
environment  
(D) 1 2 N/A N/A ≤10 
CEB NF 2 D  or CEB FF 2 D  2 4 N/A N/A ≤5  
©RSB 202 2 - All rights reserved                  30 
 CEB NF 3 D or CEB FF 3 D  3 6 N/A N/A ≤2 
CEB NF 1 R or CEB FF 1 R  Effect of water 
by 
lateral spraying  
(R) 1 2 1 N/A ≤10 
CEB NF 2 R or CEB FF 2 R  2 4 2 N/A ≤5 
CEB NF 3 R or CEB FF 3 R  3 6 3 N/A ≤2 
CEB NF 1 C or CEB FF 1 C  Effect of water  
by vertical  
penetration (C)  1 2 1 ≤15 ≤10 
CEB NF 2 C or CEB FF 2 C  2 4 2 ≤10 ≤5 
CEB NF 3 C or CEB FF 3 C  3 6 3 ≤5 ≤2 
1) N/A = not applicable  
2) The use of CEBs in R and C category environments requires using a stabiliser if the protection provided is not guaranteed.  If 
the protection provided against water damage is guaranteed, the environment is regarded as category D.  
3) If tests to establis h water absorption or abrasion are not feasible, or if the results are not available, this deficiency can be 
compensated by increasing the requirements for the dry and/or wet compressive strength by one category.  
4) The values given are the average values  obtained from tests carried out on a set of samples.  
 
8 Technical specifications for ordinary compressed earth block masonry  
8.1 Configuration characteristics  
Bonding patterns will be those used for traditional masonry using small masonry elements.  
The vertical and horizontal joints should be perfectly executed to ensure the best adhesion possible between 
blocks and mortar thus ensuring the optimal transmission of loads.  
In order to avoid superimposed vertical joints, the overlap between CEBs must b e at least 1/4 of their length.  DRS 514-1: 202 2 
31                ©RSB 2022 - All rights reserved  
 8.2 Dimensional characteristics  
The vertical and horizontal joints should be minimum 8 mm and maximum 15 mm in thickness. Locally, a 
thickness of 20 mm can be tolerated.  
Load bearing masonry will have a minimum thickness of 14  cm with a maximum slenderness ratio of 20. Non 
load bearing masonry will have a minimum thickness of 9 cm.  
8.3 Geometric characteristics  
The position of the vertical and horizontal joints must be consistent with the brickwork drawings which are 
provided befo re building work begins.  
The acceptable sweep of any surface cannot exceed 10 mm along any vertical or horizontal length. Deviation 
from verticality cannot exceed 7 mm per storey.  
a) Tolerance along the length of the masonry elements is as follows:  
b) For thin walls (<20 cm thick):  
1) for small size sections of masonry (<100 cm), the tolerance is 10 mm;  
 
2) for larger size sections of masonry (>100 cm), the tolerance is 25 mm.  
c) For thick walls  (>20 cm thick):  
1) for small size sections of masonry (<100 cm), the tolerance is 15 mm;  and 
2) for larger size sections of masonry (>100 cm), the tolerance is 30 mm.  
8.4 Physical -chemical characteristics  
8.4.1  Efflorescence  
The masonry must not display any significant and lasting efflorescence covering a large area of the surface. A 
faint whitish film or a thin band are not taken into account.  
8.4.2  Mechanical, hygrometric and physical characteristics  
The mechanical, hygrometric a nd physical characteristics of the masonry are not only a function of the quality 
of its component products (compressed earth blocks and earth mortars), but are also highly dependent on the 
quality of the workmanship and curing conditions.   
©RSB 202 2 - All rights reserved                  32 
 8.4.3  Dry characteris tic compressive strength of the CEBM wall  
The dry characteristic compressive strength (f k) of the CEBM wall must be at least equal to the dry characteristic 
compressive stress at the foot of the wall, determined by a static calculation of the vertical load  on the masonry, 
in accordance with the standards in force.  
8.4.4  Compressive strength of the CEBs  
For CEBMs in a dry or protected environment, the CEBs must have a dry compressive strength (f b dry) at least 
equal to 10 times the value of the dry characteristic  compressive strength (f k) required for the wall.  
For CEBMs in a wet environment, with no protection against water damage, the CEBs should have a wet 
compressive strength (f b wet) at least equal to 10 times the value of the dry characteristic compressive strength 
(fk) required for the wall.  
The value of the compressive strength of the CEBs fixed in this way will determine the category of resistance of 
the CEBs to mechanical constraints.  
8.4.5  Thermal resistance  
The thermal resistance of masonry under internal or external climatic conditions is specified only in the case of 
masonry expressly designed to provide thermal insulation.  
8.4.6  Thermal capacity  
Thermal capacity per unit of volume is specified only in the case of masonry specifically intended to provide 
therm al capacity. Thermal capacity is determined in the light of the project requirements.  
8.4.7  Acoustic attenuation coefficient  
The acoustic attenuation coefficient is specified only in the case of masonry expressly designed to provide 
acoustic insulation.  
8.4.8  Fire r esistance  
The fire resistance of masonry is specified only in the case of masonry expressly designed to resist fire.  
9 Technical specifications for facing compressed earth block masonry  
9.1 Configuration characteristics  
Bonding patterns will be those used for traditional masonry using small masonry elements.  
The vertical and horizontal joints should be perfectly executed to ensure the best adhesion possible between 
blocks and mortar thus ensuring the optimal transmission  of loads.  
In order to avoid superimposed vertical joints, the overlap between CEBs must be at least 1/4 of their length.  DRS 514-1: 202 2 
33                ©RSB 2022 - All rights reserved  
 9.2 Dimensional characteristics  
The vertical and horizontal joints should be minimum 8 mm and maximum 15 mm in thickness.  
Load bearing masonry will have a minimum thickness of 14 cm with a maximum slenderness ratio of 20. Non 
load bearing masonry will have a minimum thickness of 9 cm.  
Walls less than 20 cm thick will have an expansion joint every 5 m maximum.  
9.3 Geometric characteristics  
The position of the vertical and horizontal joints must be consistent with the brickwork drawings which are 
provided before building work begins.  
The ac ceptable sweep of any surface cannot exceed 7 mm along any vertical or horizontal length. Deviation 
from verticality cannot exceed 5 mm per storey.  
Tolerance along the length of the masonry elements is as follows:  
d) For thin walls (<20 cm thick):  
1) for small  size sections of masonry (<100 cm), the tolerance is 5 mm;  
2) for larger size sections of masonry (>100 cm), the tolerance is 15 mm.  
e) For thick walls (>20 cm thick):  
1) for small size sections of masonry (<100 cm), the tolerance is 10 mm;  
2) for larger size sectio ns of masonry (>100 cm), the tolerance is 20 mm.  
9.4 Appearance characteristics  
9.4.1  Drips  
The execution should be flawless and with no drips. All the mortar joints should be perfectly smooth.  
9.4.2  Cracks  
a) micro-cracks: can be tolerated on all exposed faces.  
b) macro-cracks: Conditions of acceptability for all faces:  
3) they must not exceed 0.5 mm in width;   
©RSB 202 2 - All rights reserved                  34 
 4) they must not exceed 200 mm in length;  
5) the presence of tolerated macro -cracks should not be concentrated in or found throughout one part or 
the whole of the buil t structure.  
9.4.3  Chipped corners  
Corners should be perfect and chips at corners are acceptable only within the limit of chipped corners acceptable 
for facing CEBs.  
9.4.4  Colour  
The masonry colour will be as homogeneous as possible, other than if for aesthetic reaso ns, a more varied 
appearance is required.  
9.4.5  Surface texture  
The masonry should have a homogeneous surface texture. However, one can seek special effects by 
introducing different textures in precise areas (e.g. around openings, at corners, etc.)  
9.5 Physicochem ical characteristics  
9.5.1  Pitting  
No pitting due to the bursting of expansive materials is tolerated.  
9.5.2  Efflorescence  
The masonry must not display any significant and lasting efflorescence covering a large area of the surface. A 
faint whitish film or a thin band  are not taken into account.  
9.6 Mechanical, hygrometric and physical characteristics  
The mechanical, hygrometric and physical characteristics of the masonry are not only a function of the quality 
of the component products (the compressed earth blocks and the  earth mortars), but are also highly dependent 
on the quality of the workmanship and curing conditions.  
9.6.1  Dry characteristic compressive strength of the CEBM wall  
The dry characteristic compressive strength (f k) of the CEBM wall must be at least equal to th e dry characteristic 
compressive stress at the foot of the wall, determined by a static calculation of the vertical load on the masonry, 
in accordance with the standards in force.  
9.6.2  Compressive strength of the CEBs  
For CEBMs in a dry or protected environment, the CEBs must have a dry compressive strength (f b dry) at least 
equal to 10 times the value of the dry characteristic compressive strength (f k) required for the wall.  DRS 514-1: 202 2 
35                ©RSB 2022 - All rights reserved  
 For CEBMs in a wet environment, with no protection against water damage, th e CEBs should have a wet 
compressive strength (f b wet) at least equal to 10 times the value of the dry characteristic compressive strength 
(fk) required for the wall.  
The value of the compressive strength of the CEBs fixed in this way will determine the ca tegory of resistance of 
the CEBs to mechanical constraints.  
9.6.3  Thermal resistance  
The thermal resistance of masonry under internal or external climatic conditions is specified only in the case of 
masonry expressly designed to provide thermal insulation.   
9.6.4  Thermal capacity  
Thermal capacity per unit of volume is specified only in the case of masonry specifically intended to provide 
thermal capacity. Thermal capacity is determined in the light of the project requirements.  
9.6.5  Acoustic attenuation coefficient  
The acoustic attenuation coefficient is specified only in the case of masonry expressly designed to provide 
acoustic insulation.  
9.6.6  Fire resistance  
The fire resistance of masonry is specified only in the case of structural masonry expressly designed to resist 
fire. 
 DRS 514-1: 2022  
 
Price based on  35 pages  
©RSB 2022 - All right s reserved