Reference number  
DRS 96-5: 2016  
© RBS yyyy 
© RSB 2016  
 
 RWANDA 
STANDARD  DRS 
96-5 
 
Second  edition  
2016 -mm-dd 
 
Aggregates  — Test methods  — 
Part 5: 
Methods for determination of particle 
shape – Flakiness index of course 
aggregates  
  DRS 96 -5: 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. +250 252 586103/ 582945  
E-mail: info@rsb.gov.rw  
Website: www.rsb.gov.rw  DRS 96 -5: 2016  
iii                 ©RSB 2016  All rights reserved  
 
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ ............................  iv 
1 Scope  ................................ ................................ ................................ ................................ ......................  1 
2 Normative references  ................................ ................................ ................................ ............................  1 
3 Terms and definitions  ................................ ................................ ................................ ...........................  1 
4 Sampling  ................................ ................................ ................................ ................................ ................  1 
5 Apparatus  ................................ ................................ ................................ ................................ ...............  2 
6 Preparation of t est portion  ................................ ................................ ................................ ...................  3 
7 Procedure  ................................ ................................ ................................ ................................ ...............  3 
8 Calculation and expression of results  ................................ ................................ ................................  4 
9 Test report  ................................ ................................ ................................ ................................ ..............  4 
Bibliography  ................................ ................................ ................................ ................................ ........................  6 
 DRS 96 -5: 2016  
©RSB 2016 All rights reserved                  iv 
 
 Foreword  
Rwanda Standard sareprepared 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 o f 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.  
RS96-5 was prepared by Technical Commi ttee RSB/TC 009, Building and Civil Engineering .In the preparation 
of this standard, reference was made to the following standard:  
SANS 5847:2008 Flakiness index of course aggregates  
The assistance de rived from the above source is hereby acknowledged with thanks.  
This second edition cancels and replaces the first/second/... edition (RS  96-6:2006 ), has] been technically 
revised.  
Committee membership  
The following organizations were represented on the Technical Committee on Building Materials and Civil 
Engine ering  (RSB/TC 009) in the preparation of this standard.  
Enterprise Mubiligi Paul (EMP)  
Institut d’ Ens eignement Supérieur (INES -Ruhengeri)  
NPD  
Private Consulting Company  
Ruliba clays Ltd  
Rwanda Public Procurement Authority (RPPA)  
Rwanda  Standards Board (RSB) – Secretariat  
  DRS 96-5: 2016  
1                 ©RSB 2016  All rights reserved  
 
 Aggregates  — Test methods — Part 5: Methods for determination of 
particle shape  - index of course aggregates  
1 Scope  
This standard specifies a method for determining the flakiness index of  coarse aggregate that passes a sieve 
of aperture size 75 mm and that is retained on a sieve of aperture size 4 . 750 mm. 
NOTE  The flakiness index is the mass of particles in the aggregate (expressed as a percentage of the total mass of 
the aggregate test sample) that will pass slots of specified width for the appropriate size fraction of the aggregate.  
2 Normative references  
The following referenced documents are in dispensable 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 -1, Test sieves – Technical requirements and testing – Part 1: Test sieves of metal 
wire cloth.  
RS ISO 3310 -2, Test sieves – Technical requirements and testing – Part 2: Test sieves ofperforated 
metal cloth  
RS 96-2, Methods of test for aggregates − Part 2, Guide to sampling and testing aggregates  
RS 96-3, Methods of test for aggregates − Part 3, Methods for sampling  
RS 96-4, Methods of test for aggregates −  Methods for determination of particle size distribution, sieve tests  
3 Terms and definitions  
For the pur poses of this standard, terms and definitions given 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.  
  
©RSB 2016 All rights reserved                  2 
 
 5 Apparatus  
5.1 A Sample divider,  of size appropriate to the maximum particle 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 ma ss of the test portion.  
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 also 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, whi ch can be heated 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 atleast 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 Sieve, of sizes shown in table 1.  
Table 1 — Slot dimensions, size and mass of fractions  
1 2 3 4 5 
Fraction size  
to be gauged  
mm Slot dimensions  Minimum mass of 
specimen to be 
gauged  
g 
Passing  through the 
sieve  Retained  on the sieve  Minimum length  
mm Width  
mm1) 
75.0 63.0 
 150.0  
 37.5 
 35 000  
 
63.0 
 53.0 
 126.0  
 31.5 
 20 000  
 
53.0 37.5 106.0  26.5 7 500  
37.5 
 26.5 
 75.0 
 18.75  
 2 500  
 
26.5 19.0 53.0 13.25  1 000  DRS 96-5: 2016  
3                 ©RSB 2016  All rights reserved  
 
      
19.0 13.2 38.0 9.5 500 
13.2 
 9.5 
 26.4 
 6.6 
 120 
9.5 
 6.7 
 19.0 
 4.75 
 50 
 
6.7 4.75 13.4 3.35 20 
1) Subject to a tolerance of ± 0.10 mm.  
6 Preparation of test portion  
Dry the test portion by heat ing at a temperature of 105 ± 5oC to achieve a dry mass which is constant to within 
0.1 %.  Allow to cool and weigh.  
The preparation of test portion shall comply with the procedure described in RS 96 -3, clause 7.  
7 Procedure  
7.1From the sample to be tested , weigh a test s ample  of such quantity that, foreach fraction size to be 
gauged, the minimum mass prescribed in column 5 of table 1 shall be available.  
The test s ample should be weighed to the nearest 0 .1 % of its mass (basing the size of portions tobe gauged 
on the actual fra ction sizes present in the test sample).  
7.2 Carry out a sieve analysis in accordance with RS 96-4,  separating the aggregate into therelevant fraction 
sizes given in table 1 and discarding fraction sizes that constitute less than 10 % of thetotal mass of the test 
sample . Record, to the nearest 0 .1 %, the percentage (a), retained on eachsieve.  
NOTE  For aggregates which contain clay or other materials likely to cause agglomeration of particles, a sieve analysis in 
accordance with of RS 96-4, is used.  
7.3 From the fraction sizes separated in the sieve analysis, take at least the minimum mass specifiedin column 
5 of table 1 for each fraction size. Determine, to an accuracy of 0 .2 % of its mass, the mass ofeach fraction to 
be gauged.  
7.4 Gauge pieces in each fraction size (using the corresponding slot given in table 1), and determinethe mass, 
to the same accuracy, of each quantity that passes through the appropriate individual slots.Weigh each of the 
individual size -fractions retained o n the sieves, other than the 75 mm RS test sieve, and store them in 
separate trays with their size marked on the trays.  
NOTE   Where the mass of any size -fraction is considered to be excessive, the fraction issubdivided by the methods 
described in Clause 7 of RS 96-3 provided that the mass of the subdivided fraction is not less than half the appropriate 
given in Table 1.  Under such circumstances the rest of the procedure should be suitably modified and the appropriate 
correction factor applied to determine the mass of flaky particles that would have been obtained had the whole of the 
whole of the original size -fraction been gauged.  
  
©RSB 2016 All rights reserved                  4 
 
 8 Calculation and expression of results  
8.1  The flakiness index is the to tal weight of the material passing the various thicknes s gauges or sieves, 
expressed as a percentage of the total weight of the sample gauged. The flakiness index value shall be 
calculated using the following formula:  
∑𝒂×𝒃
𝟏𝟎𝟎 
Where,  
a is Individualpercentageretained  on the test sieve  
b is the percentage  of each fraction size that passes through theindividual slots.  
8.2  Calculate, to the nearest 0 .1 %, the percentage (b) of each fraction size that passes through 
theindividual slots.  
8.3 Calculate (for each fraction size) the product (a × b) as a percentage and report, rounded -off to 
thenearest whole number, the sum of these products as the flakiness inde x of the aggregate.  
An example of the calculation of the flaki ness index is given in table 3.  
Table 3 — Example of a calculation  
1 2 3 4 
Sieve size  
mm Individual  
percentage  
retained  
a Percentages  
passing slots  
b Flakiness index  
∑𝒂×𝒃
𝟏𝟎𝟎 
 
26.5 
19.0 
13.2 13.9 
75.2 
11.6 25.8 
32.4 
36.5 3.6 
24.4 
4.2 
32.21) 
1)Report the flakiness index as 32.  
9 Test report  
The test report shall affirm that the flakiness index was determined in accordance with  RS 96 -5.  The test 
report shall include the following additional information:  
a) sample identification;  
b) flakiness index;  DRS 96-5: 2016  
5                 ©RSB 2016  All rights reserved  
 
 c) sieve analysis obtained from this test.  
  
©RSB 2016 All rights reserved                  6 
 
 Bibliography  
[1] IS 2386  – 1: 1963 (Reaffirmed 2012), Methods of test for aggregates for concrete –part 1:particle size 
and shape  DRS 96-5: 2016  
ICS 91.100.15  
 
 
©RSB 2016  All right s reserved