ICS 91.100.01  
 
Reference number  
DRS 510: 2022  
© RSB 2022  
  
 RWANDA 
STANDARD  DRS 
510  
 
First e dition  
2022 -mm-dd 
 
Stabilized soil blocks  — Specification  
   
DRS 510: 2022  
©RSB 2022  - 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  
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Toll Free: 3250  
E-mail: info@rsb.gov.rw  
Website: www.rsb.gov.rw  
ePortal: www.portal.rsb.gov.rw   DRS 510: 2022  
iii                ©RSB 2022 - All rights reserved  
 Contents  Page 
1 Scope  ................................ ................................ ................................ ................................ .............  1 
2 Normative references  ................................ ................................ ................................ ...................  1 
3 Terms and definitions  ................................ ................................ ................................ ..................  1 
4 Requirements  ................................ ................................ ................................ ................................  2 
5 Physical properties  ................................ ................................ ................................ ......................  4 
Annex  A (informative)  Common stabilized soil blocks and their dimensions  in millimetre s ............  6 
Annex  B (normative)  Determination  of compressive  strength  ................................ ...........................  11 
Annex  C (normative)  Determination  of block  density  ................................ ................................ .........  14 
Annex  D (normative)  Weathering  test ................................ ................................ ................................ ... 16 
Annex  E (normative)  Determination of linear expansion on saturation  ................................ ............  18 
 DRS 510: 2022  
©RSB 2022  - All rights reserved                  iv 
 Foreword  
Rwanda Standard s are prepared  by Technical Committees and approved by Rwanda Standards Board (RSB) 
Board  of Directors in  accordance with the procedures of RSB, in compliance with Annex 3 of the WTO/TBT 
agreement on the preparation, adoption and application of standards.  
The main task of technical committees is to prepare national standards.  Final Draft Rwanda S tandards adop ted 
by Technical committ ees are ratified  by me mbers of RSB Board of Director s for publication and gazettment as 
Rwanda Standards.  
DRS 510  was prepared by Technical Committee RSB/TC 9, Civil engineering and building materials . 
In the preparation of this standard, reference was made to the following standard:  
KS 1070:1993 , Specification for stabilized  soil blocks  
The assistance de rived from the above source is hereby acknowledged with thanks.  
Committee membership  
The following organizations were represente d 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  
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 Authority (RHA)  DRS 510: 2022  
v                ©RSB 2022 - All rights reserved  
 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 Technol ogy (UR - CST)  
Rwanda  Standards Board  (RSB) – Secretariat  
 DRS 510: 2022  
©RSB 2022  - All rights reserved                  vi 
 Introduc tion 
Soil is perhaps the oldest and most abundant build ing material  available to mankind. However, the use of soil 
as a convent ional building material  is limited  in this country. With incre asing need to house and ever gr owing 
popu lation, the use of e arth must be r e-visited in view  of its abun dance and versatility . 
 DRS 510: 2022  
1                ©RSB 2022 - All rights reserved  
 Stabilized soil blocks  — Specification  
1 Scope  
This Draft  Rwanda Stand ard specifies requirements , sampling and test methods for stabilized  soil blocks  
using cement and/or lime, and fib re for use in general co nstructi on. 
2 Normative reference s 
The following referenced documents are indispensable for the application of this document. For dated 
references, only the edition cited applies. For undated references, the latest edition of the referenced 
document (including any amendments) applies.  
RS EAS 18 -1, Cement ― Part 1: Comp osition, sp ecification and conformity criteria for common  cements  
 DRS 546, Clay products for buildings — Vocabulary  
EAS 73, Building limes (Quicklime and Hydrated Lime) — Specification  
RS ISO 10545 -2, Ceramic tiles — Part 2: Determination of dimensions and surface quality  
RS ISO 10545 -4, Ceramic tiles — Part 4: Determination of modulus of rupture and breaking strength  
RS 266, Concrete building blocks  — Specification  
3 Terms and definitions  
For the purposes of this standard, the terms and definitions  given in DRS 546 and the following  apply.  
3.1 
stabilized s oil blocks  
building bl ocks made by a  mixture of s oil with a po rtion of cement and/or lime , fibre, or sand  as a stabil izer 
3.2  
nominal size  
size of a  co-ordinating  space allocated to a mas onry unit incl uding all owances for join ts and toler ance 
Note 1 to entry:  The nominal size corresponds to the work size plus a 1 cm for joint.   
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 3.3  
work s ize 
size of a block  specified for its manufact ure to which its actual size should conform  within the specified 
perm issible deviations  
3.4 
 compr essive stre ngth 
force per unit area required to cause a set specimen  to fail under compressio n 
 
3.5  
modulus of ruptu re 
maximum load/unit area of cross section at breaking, under flexural loading conditions  
4 Requirements  
4.1 General requirements  
4.2 Materials  
4.2.1  Cement  
The cement  used for the manuf acture of stabilized  soil blocks shall conform to RS EAS 18 -1. 
4.2.2  Soils  
The soi ls used for the ma nufacture of s tabilized soil b locks shall be free of delet erious and organic materials. 
4.2.3  Lime   
The lime used for the manufacture of stabilized soil blocks shall conform to EAS 73.  
4.2.4  Sand  
The sand to be used for stabilizing the soils shall be either natural river sand, crushed stone sand or crushed 
gravel sand. It shall be free from a ny type of salt/chemical and organic matter.  
 
 
 DRS 510: 2022  
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 4.2.5  Water  
When the block is stabilized by cement, water shall be clean and free from heavy metals, salts and any other 
deleterious matter harmful to the cement reactions . 
4.3 Manufacturing  
Stabilized soil blocks shall be manufactured in a system that ensures consistency in quality. The system shall 
put in place measures to ensure the quality of raw materials, production and post -production management.  The 
system shall be documented.  
4.4 Freedom from defects  
4.4.1  Blocks shall be of homogeneous colour and texture.  
4.4.2  Blocks shall  be free from cracks, pits, broken  edges, honey comb and other defects that would  interfere 
with the proper placing of blocks or impair the  strength or performance o f construction.  
4.4.3  Blocks shall  be reasonably free from surface  flaws, laminations, crumbly and imperfect edges.  
4.5 Shape , dimensions and tolerances  
4.5.1  Dimensions  
When measured in accordance with RS ISO 10545 -2, the d imensions of stabilized soil b lock shall conform to 
Table 1.  
Table1  — Dimensions  of sta bilized soil blocks  
Length (mm)   Width (m m) Heig ht (mm)  
Nominal size  Work s ize  Nominal size  Work s ize Nominal/Work size  
200 190  100 90 55 to 65  
200 190  100 90 75 to 90  
300 290  100 90 80 to 95  
300 290  150 140 100 to 115  
400 390  150 140 105 to 120  
400 390  200 190 125 to 140  
  
  
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 4.5.2  Tolerances  
The maxim um dime nsional deviatio ns for stabil ized soil blocks m easured in accord ance with  Annex A shall  be 
as sp ecified in Table 2.  
Table 2  — Dimensional  tolerances for stabilized soil block s 
Dimension  Maximum dimensional deviation , mm 
Length  ± 3  
 
Width  ± 2  
 
Height ± 1  
 
Surface sm oothness sides ± 1  
 
Compression surface  +3  
- 1  
 
5 Physical properties  
5.1 Dry compressive strength  
The dry compressive  strength at 28 days when  tested in accordance with RS 266 , shall not be less than 2.5 
N/mm2. 
5.2 Wet compressive strength  
When stabil ized soil blocks are tested in accordance with RS 266, the minimum average wet compressive 
strength at 28  days , shall not be less th an 1.5 N/m m2. 
5.3 Modulus of rupture  
The r upture  strength when  determ ined in  accor dance with RS ISO 10545 -4, shall not be less than 0. 5N/mm2. 
5.4 Water absorption  
The water absorption  of stabilized  soil blocks  when  determi ned as describ ed in RS ISO 10545 -3, shall not 
exceed 22 % of the origi nal mass. DRS 510: 2022  
5                ©RSB 2022 - All rights reserved  
 5.5 Linear expansion on saturation  
The linear expansion on saturation of the blocks, being the average of three specimens, when determined in 
accordance with the procedure described in Annex  E, shall not exceed 0.10 %.  
5.6 Density  
The de nsity of blocks when  determi ned in accorda nce with Annex C, shall not be less than 1 6 00kg/m3. 
5.7 Weathering  
When subjected  to the weatheri ng test carried out in accordance with Annex D, the maxim um loss of mass 
shall not exc eed 3 %. 
5.8 Shrinkage cracks  
Shrinkage cracks shall not be more than 0.5 mm wide and shall not exceed in length 50 % of the block 
dimension to which they are parallel , where they are not parallel, their projected length s hall be measured . 
  
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 Annex  A 
(informative)  
 
Common stabilized soil blocks and their dimensions  in millimetre s  
 
Figure  A.1 — Stand ard block  
 
DRS 510: 2022  
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 Figure A.2  — Straight sin gle interlock ing block  
 
Figure  A. 3 — Straight d ouble interloc king block  
DRS 510: 2022  
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Figure A.4 — Curved single interlocki ng block  
 
 
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 Figure A.5 — Curved double interlocki ng block  
 
Figure A.6 — Wide for mat interlocking  block  
 
Figure A.7 — Chamfered edges  dimen sion 
DRS 510: 2022  
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 Annex  B 
(normative)  
 
Determination  of compressive  strength  
B.1 Test specimens  
Ten w hole b locks shall be sel ected at r andom from t he samp le after c arrying out the dime nsional ch ecks.  Five 
blocks  shall be used for dry c ompressive str ength and anoth er five for wet com pressive strength.  
B.2 Principle  
B.2.1  Dry compr essive  strength  
A unit is placed in a co mpressi ve testing  machi ne and subjected to  incre ased compression until it fails. The 
compression  strength is  calculated from the  maximum load.  
B.2.2  Wet compressive  strength  
A unit is immersed in wat er for a s pecified per iod of time. The unit is then test ed usi ng the s ame pri nciples as 
clause B.2.1.  
B.3 Apparatus  
B.3.1  Loading  machine  
A com pressi on loadi ng machine either hydraul ic or screw type with  adequate ca pacity and ca pable of applying 
the loa ds at rates sp ecified in cla use B.4.  
The m achine shall be fitted with two ste el platens  which shall be sel f-align ing. 
The be aring fac es of both  plate ns should exce ed the test sp ecimen by not less  than 15 mm length in length a nd 
breadth a nd shall not dep art from a pla ne by more than  0.06 mm. Should the b earing fac es of the platens be 
smaller than  required, st eel plates of ad equate size may be pl aced centrally betw een th em and the test 
spec imen. Their thick ness shall be equal to at least one -third of the great er difference in d imens ion in between 
the mach ine plat en and the test sp ecimen, when centrally placed but not less than 25 m m. 
B.3.2  Measuri ng rule r 
A rule r that c an be re ad accurately to 1.0 mm  over the  dime nsions of the units be ing tested.   
©RSB 2022  - All rights reserved                  12 
 B.3.3  Water b ath 
A water  bath of suffici ent size to hold the specimens without  them  touching each other  and sufficient depth to 
ensure that the s pecim ens will be co mpletely immers ed in water f or the full duration  of the te st. 
B.4 Dry compressi ve strength  
B.4.1  Procedu re 
B.4.1.1  Measure and  record the followi ng dime nsions as per RS ISO 10545 -2, to the nearest milli metre:  
a) the width  (B); and 
b) the length  (L). 
B.4.1. 2 Clean and wipe the surfaces of the test specimen removi ng all loose  debris. Clean the 
bearing surf aces of the plate ns on the testing mach ine, and any steel plates  to be placed  between  the sp ecimen 
and platen . 
B.4.1. 3 Place the specim en between  two pieces of 3 mm thick plywood,  the length  and width of which  
shall exce ed the correspo nding dime nsions of the specimen by less than 25 mm each  plywo od shall be used 
only o nce. The specimen shall be pla ced in the testing machine such that the centre of  the bed face coi ncides 
with the lo ading axis of the machine . 
B.4.1. 4 Apply the load without s hock and incr ease it contin uously at a uniform rate of 150 kN/min u ntil 
failure occurs.  
B.4.1. 5 Observe a nd record the maximum load  (WD) at failure.  
B.5 Wet compr essive strength  
B.5.1  Procedu re 
a) Measure and record the followi ng dime nsions to the n earest millimetre:  
i) the width  (B) of each sp ecimen as described in  clause A3;  and 
ii) the width ( B) of each specimen as described in clause A3;  
b) the length (L) of each specimen as described in clause A3. (b)  The specimen shall be immersed in water 
at 15 0C to 30 0C for 24 h ; 
c) the specimen shall be removed from the water bath. They shall then be wiped clean with a piece of cloth ; 
d) the procedure for the compression testing shall proceed as described in clause B.4.1 to clause B.4.1 (d); 
and DRS 510: 2022  
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 e) Observe and record the maximum load (WW) at failure.  
B.6 Calcul ation of results  
The compressive  strength of each sp ecimen (dry or we t) shall be calculated from the the foll owing expr essions: 
𝐶𝐷=𝑊𝐷
𝐴 𝑜𝑟 𝐶𝑊=𝑊𝑊
𝐴  
where 
CD = dry  compressive strength in N /mm2;  
CW = wet compressive strength in N/mm2; 
WD = total load at which the dry sp ecimen fails, in N ewtons;  
WW = total load at wh ich the wet sp ecimen fails, in N ewtons;  
A = the smal ler bed f ace area, in s quare millimetres.  
Length (L) and width (B) t aken for  whichever of two bed fac es pro duces the sm aller area.  
B.7 Repo rting 
Report the avera ge of the compressive strength; eith er dry or  wet of the five spec imens . 
   
©RSB 2022  - All rights reserved                  14 
 Annex  C 
(normative)  
 
Determination  of block  density  
C.1 Test specimens 
Select  at random three blocks from the sample for testing.  Carry out the dime nsional measurements as 
described in Annex RS ISO 10545 -2, noting the a verage le ngth, height and  width of each bl ock. 
C.2 Appa ratus 
C.2.1   Drying oven 
Thermostat ically control led drying ov en capable of  maintaini ng temp erature at 105 °C  ± 5 °C. 
C.2.2  Calcul ating of volume  
Calculate the  gross vol ume of the blocks to the near est 250 m m3 by multiplying the avera ge thickn ess by the 
average length and height of the block.  
C.3 Procedu re 
Dry the thr ee specimen blocks for at le ast 24 h in a ventilated ov en at 105 ± 5 °C. 
Cool the b locks to a mbient  temperat ure and weigh. Repeat th ese steps until the  mass lost in one cycle does 
not exceed 0.05  kg. 
C.4 Calculation of density  
𝐶𝑏=𝑀
𝑉 
where 
Cb block density (in kg/m3); 
M  oven dry mass (in  kg); and 
V  gross volume in blocks (in m3). DRS 510: 2022  
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 C.5 Repo rting 
Report the d ensity to the near est 10 kg/ m3.  
©RSB 2022  - All rights reserved                  16 
 Annex  D 
(normative)  
 
Weathering  test 
D.1 Test specimens 
Two whole  blocks shall be selected from the sample  of blocks  obtained as descr ibed under Annex A, after 
carrying  out the test for dime nsional conformity. The bl ocks sh all be des ignated “sp ecimen A” and “specimen 
B”, resp ectively.  
D.2 Appa ratus 
D.2.1  Balan ce 
A balance or  scale of a 20-kilogram capacity, s ensitive to 50 g.  
D.2.2  Drying ovens 
Two th ermostatically c ontrolled drying  ovens, one capab le of maintaining tem perature at 1 05 ± 5 °C and the 
other capable of maintaini ng temperature at 70 °C  ± 5 °C. 
D.2.3  Water b ath 
A suitable ta nk for subm erging s pecimens in wat er at room temp erature. 
D.2.4  Wire sc ratch brush  
A brush ma de of 50 mm x  1.6 mm flat with 0.4 mm wire br istles assemb led in 50 longitudi nal rows and 10 
transverse r ows of bristl es on 200 mm x 60 mm har dwood block.  
D.3 Procedu re 
D.3.1 Oven dry sp ecimen A at 1 05 °C ± 5 °C for at  least 12 h or  to a co nstant mass. From this weight, 
calculate the  oven – dry weight (W 1) of specimen A. Carry out fur ther o peratio ns on sp ecimen B only .  
D.3.2 Submerge  specim en B in water  at room temp erature for 6 h. Remove  and immediately  place it in an 
oven at 70 °C for 42 h and  remove. Br ush all are as of the sp ecimen twice with t he wire  scratch brush. Hold the 
brush with the long axis of the brush  paral lel to the longitudi nal axis of the specim en or p arallel to the en ds as 
required to co ver all a reas of the sp ecimen. Apply these str okes to the  height  and width of the specimen  with 
a firm stroke corresponding to approxi mately  1.5 kg force.  Eight een to twenty vertical  brush strokes are required  
to cover the sides of the specimen twice and four  strokes are r equired on e ach end. 
NOTE  Measure the pr essure as follows:  DRS 510: 2022  
17                ©RSB 2022 - All rights reserved  
 a) clamp  a specimen  in a vertical  position on the edge of a platform  scale  and set the scale  to zero . 
b) apply vertical brushing str okes to the sp ecimen and note the  force necessary to reg ister approximately 1.5 
kg. 
D.3.3 The proced ures d escribed in cla use D.3.2 constitutes one c ycle (48 h) of weath ering test. Cont inue the 
procedure for 12 c ycles. After 12 cycl es of test, dry the sp ecimen to co nstant weight at 1 05 ± 5  °C and det ermine 
the final  oven – dry weight (W f) of the s pecimen. The data collected permits calculations of the soil – cement 
loss of the specimen after the pr escribed test of  12 cyc les 
D.4 Calcul ation and repo rt 
D.4.1 Calculate the  soil – cement  loss of the speci men as a percenta ge of the original ly calcu lated oven – 
dry weight (W i) of the s pecimen as foll ows: 
Soil – cement  loss ,per cent  =𝑊𝑖−𝑊𝑓
𝑊𝑓×100 
where  
Wi = Oven dry weight ; 
Wf = Final oven -dry we ight. 
  
©RSB 2022  - All rights reserved                  18 
 Annex  E 
(normative ) 
 
Determination of linear expansion on saturation  
E.1  Test specimens  
Randomly select three full size specimens from the sample of blocks which has been found satisfactory in 
respect of dimensional and visual requirements. These blocks shall be designated as specimens A, B and C 
respectively.  
E.2 Apparatus  
A vernier calliper w ith a least count of 0.1 mm and length more than that of the block, ventilated or 
thermostatically controlled oven capable of maintaining temperature of 110  °C ± 5 °C and a length comparator 
attached with a dial gauge having a least count of 0.001mm (see F igure E . 1). 
E.3 Procedure  
E.3.1  Cure the specimens for 28 days.  
E.3.2  Remove the specimens from water and dry them in the oven at 60 ± 5ºC till they attain constant weight 
and then allow them to cool down at ambient temperature such that they attain room te mperature.   
E.3.3 Measure the lengths of the longest dimensions of all the three specimens using vernier calliper and 
note them as initial length of the specimens, L Ai, LBi, and L Ci respectively.  
E.3.4 Fix a metal point or small strip using water insolubl e glue on the top surface of the dried specimens and 
position the block in the apparatus as shown in Fig. 1.  
E.3.5 Now, note down the initial reading of the dial gauge.  
E.3.6 Remove the specimens from the apparatus without disturbing the digital dial gauge and then soak them 
in water for 24 h at room temperature.  
E.3.7 After 24 h take out the saturated specimens and position them in the length comparator apparatus such 
that th e metal point fixed on the surface of the block faces the dial gauge tip. Note the final reading of the digital 
dial gauge. Ensure that the dial gauge in the apparatus is undisturbed throughout the duration of test. The 
difference between the initial dial gauge reading and final dial gauge reading gives the linear expansion of the 
specimens, L Ae, LBe, and L Ce respectively, in mm.  
E.4 Calculation and report  
E.4.1 Calculate the percentage linear expansion on saturation of each specimen as the difference between 
the initial length and final length after saturation expressed as a percentage of the initial length.  DRS 510: 2022  
19                ©RSB 2022 - All rights reserved  
 Percentage linear expansion on saturation for specimen  
 
Percentage linear expansion on saturation for specimen  
 
Percentage linear expansion on saturation for specimen  
 
E.4.2  Report all results separately for each specimen and as the average for the three specimens.  
Linear expansion on= (Le / Li ) × 100 sa turation (percent)  
 
©RSB 2022  - All rights reserved                  20 
  
Figure E.1 — Set-up for length comparator  
 
 
 
DRS 510: 2022  
21                ©RSB 2022 - All rights reserved  
 𝑎 
𝐶𝑏=𝑀
𝑉 
 
Soil –×100 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 EAST AFRICAN STANDARD  EAS nnnn-n:yyyy  
 
 
Price based on 22 pages  
©RSB 2022 - All right s reserved   
 Bibliography  
[1] ISO 8336:2017 Fibre -cement flat sheets — Product specification and test methods  
[2] IS 1725: 2013  Stabilized soil blocks used in general building construction — Specification  WD 510: 2022  
 
Price based on 22 pages  
©RSB 2022 - All right s reserved   
 𝑎 
𝐶𝑏=𝑀
𝑉 
 
Soil –×100 
 
 
 
 
 
 
 
 
 
 
 
 
  
  
 
 
Bibliography  
[1] ISO 8336:2017 Fibre -cement flat sheets — Product specification and test methods  
[2] IS 1725: 2013  Stabilized soil blocks used in general building construction — Specification