KENYA STANDARD  FDKS 2982 :2023 
ICS ##.###  
1st  Edition  
  
 © KEBS 202 3  
 Portland cement Clinker — 
Specification  
 
 
  
TECHNICAL COMMITTEE REPRESENTATION  
The following organizations were represented on the Technical Committee:  
1. Apex Systems Consulting Group Limited  
2. Aurecon Kenya  
3. Bamburi Cement  
4. Blackberry House Ltd  
5. Drychem Kenya S olutions Ltd.  
6. East African Portland Cement Company Plc  
7. Institution of Engineers of Kenya  
8. Institut ion of Quantity Surveyors of Kenya  
9. Institution of Engineers of Kenya  
10. Jiangxi Youse  
11. Kenya Builders & Concrete Co Ltd  
12. Kenya Electricity Transmission company Limi ted 
13. KTDA Power Company Limited  
14. Moi University  
15. Mombasa Cement Ltd.  
16. Multimedia University of Kenya  
17. Nairobi Western Bypass Project  
18. Ministry of Transport, Infrastructure, Housing, Urban Development and Public Works  
19. Royal Automation Systems  
20. Technical University  of Kenya  
21. Technical University of Mombasa  
22. University of Nairobi  
23. Kenya Bureau of Standards — Secretariat  
REVISION OF KENYA STANDARDS  
In order to keep abreast of progress in industry, Kenya Standards shall be regularly reviewed.  Suggestions 
for improvements  to published standards, addressed to the Managing Director, Kenya Bureau of Standards, 
are welcome.  
© Kenya Bureau of Standards,202 3 
Copyright. Users are reminded that by virtue of Section 25 of the Copyright Act, Cap. 130 of 2001 of the Laws of Kenya, co pyright 
subsists in all Kenya Standards and except as provided under Section 25 of this Act, no Kenya Standard produced by Kenya Bure au of 
Standards may be reproduced, stored in a retrieval system in any form or transmitted by any means without prior permi ssion in writing 
from the Managing Director.FDKS  2982:2023 
 
 
  
 
Portland cement Clinker — 
Specification  
 
Kenya Bureau of Standards, Popo Road, Off Mombasa Road,  
P.O. Box 54974 - 00200,  Nairobi, Kenya  
 +254 020 6948000, + 254 722202137, + 254 734600471  
 info@kebs.org  
 @KEBS_ke  
 Kenya  bureau of standards (kebs)   
Foreword  
 
This Kenya Standard was prepared by the Cement Technical Committee under the guidance of the Standards 
Projects Committee, and it is in accordance with the procedures of the Kenya Bureau of Stan dards. 
In Kenya, Portland cement clinker has been imported  for many years . However , recently clinker has started 
being produced in Kenya . In view of the increased interest for use of local clinker as tradable commodity and 
in order to provide a common stan dard reference for this material, these specifications are laid down to cover 
requirements of clinker . 
 
This standard lays down minimum requirements expected from clinker to the used for manufacture of various 
types and grades of cements. However, dependin g upon the special intended requirements of a particular 
type or grade of cement, the manuf acturer may design for appropriate additional requirements of clinker, if so 
desired subject to compliance of the minimum requirements specified in this standard.  
 
For the purpose of deciding whether a particular requirement of this standard is compiled wi th, the final value, 
observed or calculated, expressing the result of a test or analysis shall be rounded off in accordance with ISO 
17025; Rounding Me asurements . The number of significant places retained in the rounded off v alue should be 
the same as that specified value in this standard.  
 FDKS 2982 :2023   
 
© KEBS 202 3– All rights reserved   
  
Portland cement Clinker — Specification  
 
 
1. Scope  
 
This standard covers various requirements such as, manufacture, chemical, phas es and physical 
requirements, storage and transportation of Portland cement clinker used to produce cement meeting 
relevant Kenyan Standard specifications.  
 
2.  References  
 
The following standards contain provision which through reference in this text, consti tute provisions of this 
standard. At the time of publication , the editions indicated were valid. All standards are subject to revision, 
and parties to agreement based on this standard are encouraged to investigate the possibility of applying the 
most recen t editions of the standards indicated below:  
 
KS EAS 148 -6: 2017 Cement -Test methods Part 6: Determination  of fineness.  
KS EAS 148 -2:2017 Cement -Test method Part 2: Chemical  analysis.  
KS EAS 183:2000 Cement - Definitions and terminology  
KS 1755 -4.2:2001 M ethods of test for limes and limestones - Part 4.2: Soundness - Le chatelier.    
KS 1755 -4.3:2001 Methods of test for limes and  limestones - Part 4.3: Soundness - Autoclave).  
KS EAS 148 -3:2017Cement -Test methods Part 3: Determination  of setting times and s oundness.  
 
3.  Terminology  
 
For the purpose of this standard, the definitions given in KS EAS 183 shall apply.  
 
4.  Manufacture  
 
Portland cement clinker consisting mainly of calcium silicates (C 3S,C 2S), aluminates (C 3A) and ferrites(C 4AF) 
shall be obtained by he ating to incipient fusion, a pre -determined and homogenous mixture of materials 
principally consisting of lime (CaO), and silica (SiO 2) with smaller proportions of alumina (Al 2O3) and iron 
oxide (Fe 2O3). 
 
5.  Clinker requirements  
 
5.1. The Portland cement clinker shall conform to the requirements given in Table 1, when tested in 
accordance with the methods given in KS EAS 148 -2. For the purpose, the representative clinker shall be 
ground to pass 150 μm BS sieve and tested.  
 
Table 1 requirements of common clinkers  
 
Serial 
no Parameter  unit Requirement  
 
1.  Equivalent alkali  
=Na 2O+ 0.658K 2O % ≤1 
2.  Tri-calcium % ≤ 12 FDKS 2982:2023  
aluminate (C 3A) 
3.  Tri-calcium silicate 
(C3S) % ≥55   
4.  Moisture  % ≤0.5 
5.  Di-calcium silicate 
(C2S) % ≤25 
6.  Loss on ignition, 
LOI % ≤1.0 
7.  MgO  % ≤5 
8.  Free L ime % ≤2.5 
9.  CaO /SiO 2  ≥2 
 
 
 
Table 2 Physical requirements ( clause 6.1)  
SL 
No  Characteristics  
 Requirement  
 Test method   
 
i.  Soundness:    
 
KS 1755  Part 4.2  a) By Le -Chatelier method, 
mm, Max  10 
 b) By autoclave test 
method, percent, Max 0.8 KS 1755  Part 4.3 
ii.  Setting time:   KS EAS 148 Part 3  
 a) Initial, min, Min  ≥ 45  
    
 
Table 3 Granulometric composition of clinker for general guidance  
SI No  
 Clinker size  
mm Proportion by mass  
Percent  
i)   5 ≤5 
ii)  5 - 40 90 
iii)   40 ≤5 
 
6.  Transporta tion of clinker  
 
6.1. Portla nd cement clinker shall be supplied duly covered in trucks or suitable railway wagons or in ships or 
barges of suitable capacity. The supplier and the purchaser shall ensure that clinker is transported in 
environmental friendly manne r minimizing dust pollu tion and spillage of clinker.  
 FDKS 2982:2023  
6.2.  For exports, clinker shall be supplied in suitable vessels with covered top to avoid any contact with 
moisture or sea water, supplier shall ensure that clinker is transported to waterfront  or loading terminals in 
environment ally friendly manner.  
 
7.  Storage  
 
Portland cement clinker shall be stored in such a manner as to permit easy access for proper inspection and 
to protect it from deterioration during storage. It shall be stored in proper storage area to protect it from entry  
of moisture or any other contamination; and can be stored in covered gantry or silo.  
 
8.  Manufacturer’s certificate  
 
The manufacturer shall furnish a certificate to the purchaser or his representative within mutually agreed 
timeline s of the Portland cement  clinker stating that the material conforms to all the requirements of this 
standard.  
 
9. Delivery and marking  
 
Supplies of Portland cement clinker in bulk shall be made by agreement between the purchaser and the 
supplier. Each consign ment shall be accompanie d by a certificate bearing the following  
a. the manufacturer’s name, address, (factory physical address) and/or trademark;  
b. standard designation of clinker;  
c. net weight of clinker in kilograms/tonnes;  
d. date of dispatch and/or batch numbe r 
e. the words ‘Portland ce ment clinker  
f. quality mark (KEBS  standardization mark, diamond mark, import mark)  
 
 
10.  Sampling  
 
10.1.   A sample or samples for testing may be taken by the purchaser or his representative, or by any person 
appointed to superintend the work for purposes of which the  Portland cement clinker is required or by the 
latter’s representative.  
 
10.1.1.  The samples shall be taken within three weeks of the delivery and all the tests shall be commenced 
within one week of sampling.  
 
10.1.2.  When it is not possible to te st the samples within one  week, the samples shall be packed and 
stored in airtight containers and tested at the earliest but not later than 3 months since the receipt of samples 
for testing.  
 
10.2.  The scale of sampling and criteria for conformity shall be as pr escribed in Annex A.  
 
10.3.  The manufacturer or supplier shall afford every facility and  shall provide all labour and materials for 
taking and packing the samples for testing the Portland cement clinker and for subsequent identification of 
the Portland cement c linker samples.  
 
11. Tests  
 
11.1.   The sample or samples of Portland cement clinker for test shall be taken as described in 11 and shall 
be tested in the manner described in the relevant clauses of this standard.  
 
11.2.   Independent testing  
 
11.2.1.  If the purchaser or his repres entative requires independ ent tests, the samples shall be taken before 
or immediately after delivery at the option of the purchaser or his representative, and the tests shall be 
carried out in accordance with this standard on the written instructions of th e purchaser or his represe ntative.  
 
11.2.2.   After a representative sample has been drawn, tests on the sample shall be carried out as 
expeditiously as possible.  
 FDKS 2982:2023  
12.  Rejection  
 
Portland cement clinker shall be rejected, if it does not comply with any of the requirem ents of this 
specification  or purchaser specification, whichever is higher. Rejected clinker shall be separately stored with 
proper identification. Portland cement clinker remaining in bulk storage at the plant, prior to shipment, for 
more than six months,  or in local storage in th e hands of a vendor for more than three months after 
completion of the tests, may be retested for physical requirements before use and may be rejected, if it fails 
to conform to any of the requirement of this standard.  
 
Annex A  
Sampling and criteria for co nformity for clinkers  
A-1 scale of sampling  
A-1.1 Lot  
The quantity of clinker from the same manufacturing unit and offered for inspection at one time not 
exceeding 2 000 t shall constitute a lot.  
 
The samples shall be selected and  examined for each lot sep arately for ascertaining their conformity to the 
requirements of this standard.  
 
A-2 Sampling from bulk storage (silos)  
 
A-2.1 Sub -lots 
For the purpose of sampling, the quantity of clinker in the bulk storage shall be divided into  number of 
sublots dependi ng upon the mass of the lot, in accordance with Table 4.  
 
Table 4 Number of Sub -lots into which a Lot is to be Divided  
SI 
No Mass of the Lot  
t Number of sub -lots 
 
 
i)  Up to 100  2 
ii)  101 to 200  3 
iii)  201 to 300  4 
iv)  301 to 500  5 
v)  501 to 1000  6 
vi)  1001 to 2000  7 
 
 
 
A-2.2 Gross sample  
 
The gross sample shall be taken from a sub -lot by taking increments at regular intervals when the Portland 
cement clinker is being charged into the bulk storage or is being discharged from the bulk storage . If there is 
more than one  opening for charging or discharging, the increments shall be taken from each opening. 
Increments shall be taken from each sub -lot and each increment shall weigh at least 2 kg. It shall be ensured 
that the quantity of sample so c ollected is sufficient for tests prescribed in this standard.  
 
A-3 Sampling from wagons or trucks  
 
A-3.1 This method shall apply when Portland cement clinker in bulk is received in wagons or trucks.  
 
A-3.2 Sub -lots 
 
For the purpose of sampling, the quantit y of Portland cement clinke r in wagons or trucks shall be divided into 
a number of sub -lots depending upon the mass of the lot, in accordance with Table 4. The sub -lots shall 
consist of approximately equal number of wagons or trucks. Minimum two trucks/wag ons shall be selected at 
random from each sub -lot. 
 
A-3.3 Gross Sample  FDKS 2982:2023  
The gross sample shall be taken from a sub -lot with the help of a suitable sampler by taking increments of 
not less than 2 kg from 6 evenly distributed points in each selected wagon or truck and the mass of gross  
sample shall be minimum 24 kg.  
 
A-4 Sampling from ships and barges  
 
A-4.1 This method shall apply when clinker in bulk is received in ships or barges.  
 
A-4.2 Sub -lots 
For the purpose of sampling, the quantity of clinker in a shi p or barge shall be divided  into a number of 
sublots depending upon the mass of lot, in accordance with Table 4.  
 
A-4.3 Gross sample  
The gross sample shall be taken from a sub -lot with the help of suitable sampler by taking increments at 
regular intervals when Portland cement clinke r is being loaded into or discharged from the ship or the barge. 
Increments shall be taken from each sub -lot and each increment shall weigh at least 2 kg, and the mass of 
gross sample shall be minimum 24 kg.  
 
A-5 Reduction of gro ss sample  
 
A-5.1 Equal quantities of the material shall be taken from each of the gross sample representing the sub -lot 
into which the lot has been divided and mixed together to constitute a composite sample representing the lot 
as a whole. The mass of the  composite sample  shall be about 24 kg.  
 
A-5.2 The composite sample shall be divided into 3 equal parts; one for the purchaser, another for the 
supplier and the third to be used as a referee sample, The referee sample shall be used in case of a dispute 
between the purchase r and the supplier. Each of these parts shall then be placed in a suitable container and 
labelled with full identification particulars, such as supplier’s name, lot number, sub -lot number, date of 
sampling, etc.  
 
A-6 Number of tests and cr iteria for confor mity 
 
A-6.1 A composite sample shall be tested for all the requirements specified in this standard.  
 
A-6.2 All the test results shall satisfy the requirements of the standard to declare the conformity of the lot.