Reference number  
DRS 96-6: 2016  
© RBS yyyy 
© RSB 2016   
 RWANDA 
STANDARD  DRS 
96-6 
 
Second  edition  
2016 -mm-dd 
 
Aggregates — Test methods  — 
Part 6: 
Methods for determination of shell  content  
in course aggregates  
 DRS 96-6: 2016  
©RSB 2016 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 2016  
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  
Tel. +2 50 252 586103/ 582945  
E-mail: info@rsb.gov.rw  
Website: www.rsb.gov.rw  DRS 96-6: 2016  
iii                 ©RSB 2016  All rights reserved  
 
 Contents  Page  
1 Scope  ................................ ................................ ................................ ................................ ......................  1 
2 Normative references  ................................ ................................ ................................ ............................  1 
3 Terms and definitions  ................................ ................................ ................................ ...........................  1 
4 Sampling  ................................ ................................ ................................ ................................ ................  1 
5 Apparatus  ................................ ................................ ................................ ................................ ...............  1 
6 Preparation of test portion  ................................ ................................ ................................ ...................  2 
7 Procedure  ................................ ................................ ................................ ................................ ...............  3 
8 Calcul ation and expression of results  ................................ ................................ ................................  3 
9 Test report  ................................ ................................ ................................ ................................ ..............  3 
 
 DRS 96-6: 2016  
©RSB 2016 All rights reserved                  iv 
 
 Foreword  
Rwanda Standard s are prepared  by Technical Committees and approved by R wanda Standards Board (RSB) 
Board  of Directors in  accordance with the procedures of RSB, in compliance with Annex 3 of the WTO/TBT 
agreement on the preparation, adoption and application of standards.  
The main task of technical committees is to prepare national standards.  Final Draft Rwanda S tandards 
adopted by Technical committ ees are ratified by me mbers of RSB Board of Director s for publication and 
gazett ed as Rwanda Standards.  
RS 96-6 was prepared by Technical Committee RSB/TC 009, Building and Civil Engineering . In the 
preparation of this standard, reference was made to the following standard  : 
KS 1238 -7:2003 Methods of testing aggregates Part 7: Method for determination of shell content in coarse 
aggregates  
The assistance de rived from the above source is hereby acknowledged with th anks.  
This second edition cancels an d replaces the first edition (RS  96-6: 2006 ), which has been technically revised.  
Committee membership  
The following organizations were represented on the Technical Committee on Building Materials and Civil 
Engineering  (RSB/TC 009) in the preparation of this standard.  
Rwanda Housing Authority  
 
National University of Rwanda/College of Science and Technology  
 
S.I Consulting Company Ltd  
 
IPRC Kigali  
 
Ruliba Clays Ltd  
Entreprise Mubiligi Paul  
Standards for sustainability  
Private Sector Federation  
Rwanda Public Procurement Authority  
 DRS 96-6: 2016  
v                 ©RSB 2016  All rights reserved  
 
 Horizon Construction  
 
INES Ruhengeri  
 
Rwanda Standards Board (RSB) – Secretariat  DRS 96-6: 2016  
©RSB 2016 All rights reserved                  vi 
 
  DRS 96-6: 2016  
1                 ©RSB 2016  All rights reserved  
 
 Aggregate  — Test methods  — Part 6: Methods for determination of shell 
content in  course aggregate  
1 Scope  
This DRS 96-6 describes the method for the determination of the shell content of coarse aggregate.  
2 Normative references  
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 ISO  3310  Specification for test sieves.  
RS 96-2, Methods of test for aggregates −Part 2: Guide to sampling and testing aggregates.  
RS 96-3, Method s of test for aggregates − Part 3: Methods for sampling.  
RS 96-4, Methods of test for aggregates − Part 4: Methods for determination of particle size distribution.  
 
3 Terms and definitions  
For the purposes of this part 6 of RS 96, the terms and definitions g iven in RS 96,part 2 and Part 3 apply.  
4 Sampling   
The sample used for the test (the laboratory sample) shall be taken in accordance with the procedure 
described in RS 96 -3, Clause 6.  
5 Apparatus  
5.1 A Sample divider,  of size appropriate to the maximum particl e size to be handled or alternatively a flat 
shovel and clean, flat, hard horizontal surface, e.g. a metal tray for use in quartering.  
NOTE    A suitable divider is the riffle box illustrated in RS 96-3. 
5.2   A ventilated oven , thermostatically controlled to maintain a temperature of 105 ± 5 oC                                                                                                          
5.3    A balance , of suitable capacity accurate to 0.1 % of the mass of the test portion.   
©RSB 2016 All rights reserved                  2 
 
 NOTE   In general two  balances, one of approximately 5 kg capacity accurate to 1 g and the other of approximately 
500 g capacity accurate to 0.1 g, will suffice.  If aggregate of larger than 28 mm nominal size is to be tested a balance of 
50 kg capacity accurate to 10 g will a lso be required.  
5.4 Test sieves , of aperture sizes as given in columns 1 and 2 of ta ble 1, and that comply with the 
requirements of RS ISO  3310 -1 or RS ISO  3310 -2. 
5.5   A mechanical sieve shaker , (optional).  
5.6   Trays , of suitable size, which can be h eated in the ventilated oven (see 5.2) without damage or change 
in mass.  
5.7   A metal thickness gauge ,  of any suitable form,  of nominal thickness 1.6 mm, and that has at  least one 
slot for each fraction to be tested. The slots are rectangular and their dimensions conform to the relevant 
values given in columns 3 and 4 of table 1.  
5.8 Test sieves, complying with RS ISO 3310 -1 or RS ISO 3310 -2  and with aperture sizes of 10 .0 mm and 
5.0 mm, and with the appropriate sizes of lids and receivers . 
6 Preparation  of test portion  
Reduce the sample by the procedures described in Clause 7 of RS 96- 3 to produce a test portion that 
complies with Table 1 with due allowance for the later rejection of particles passing a 5.0 mm  test sieve. Dry 
the test portion by heating  a temperature of 105 ± 5 °C to achieve a dry mass is constant to within 0.1 %. 
Allow to cool and weigh.  
Table 1— Minimum mass of test portion  
Nominal size of material  
mm Minimum mass of test portion after 
rejection of undersize particles  
g 
75 
63 
53 
37.5 
26.5 3 500 
20 000  
7 500  
2 500  
1000  DRS 96-6: 2016  
3                 ©RSB 2016  All rights reserved  
 
 199.5  
6.7 500 
50 
20 
 
7 Procedure  
7.1    Separate the test sample into test fractions by sieving through 10.0 mm and 5.0 mm test sieves,  
ensuring that the sieves are not overloaded. Weigh the fraction ret ained on the 10.0 mm test sieve to the 
nearest gram and record as mass M 10. Similarly weigh the fract ion retained on the 5.0 mm test sieve and 
record as mass M 5. Discard any aggregate passing the 5.0 mm test sieve.  
7.2 Spread each fraction, separately, on a clean, dark surfa ce and separate out any shell fragments by hand 
picking under a good light. Weigh the total shell content in each fraction to the nearest gram and record as m 10 
and m 5. 
NOTE   When sieve analysis in accordance with RS 96 -4 has been done, the combined fracti on retained on the 10.0 mm 
and larger test sieves and the combined fractions passing the 10.0 mm and retained on the 5.0 mm test sieves may be 
used for the determination of shell content.  
8 Calculation and expression of results  
Calculate the value of the she ll content, expressed as a percentage, from the formula:  
Shell content coarser than 10 mm =  100
 (
) 
and 
Shell content finer than 10 mm = 100
  
Express the value of each shell content to the nearest whole number.  
9 Test repor t 
The test report shall affirm that the shell content was determined in accordance with this standard  and 
whether or not a certificate of sampling is available. If available, a copy of the certificate of sampling shall be 
provided. The test report shall in clude the following additional information:  
a) sample identification;  and  
©RSB 2016 All rights reserved                  4 
 
 b) shell content  DRS 96-6: 2016  
ICS 91.100.15  
 
©RSB 2016  All right s reserved