KENYA STANDARD   KS 573: 2014 
   ICS 77.140.15; 91.080.40  
  
 
 
 
  
 
 
  
 
  
 
 
High yield steel bars for the reinforcement 
of concrete — Specification 
 
 
 
 
 
 
 
 
 
 
 
 
  
 
  
 
  
 
© KEBS 2014               Fourth Edition 2014  APPROVED 
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ii         © KEBS 2014 — All rights reserved TECHNICAL COMMITTEE REPRESENTATION 
 
The following organizations were represented on the Technical Committee: 
 
Architectural Association of Kenya Athi River Steel  
Consumer Information Network  
Devki Steel Mills Ltd. 
Doshi Group of Companies  Howard Humphreys (E.A) Ltd. 
Institute of Engineers of Kenya  
Kenya Association of Manufacturers  Kenya United Steel (2006) Co Ltd.  
Mangat I. B  Patel & Partners 
Ministry of Transport and Infrastructure Moi University — Department of Civil and Structural Engineering  
National Housing Corporation 
Tononoka Steel  Wire Products Limited  
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, 2014 
 
Copyright. Users are reminded that by virtue of Section 25 of the Copyright Act, Cap. 12 of 2001  of the Laws of Kenya, copyrig ht 
subsists in all Kenya Standards and except as provided under Section 26 of this Act, no Kenya Standard produced by Kenya Bureau  of 
Standards may be reproduced, stored in a retrieval system in any form or transmitted by any means without prior permission in w riting 
from the Managing Director. 
 
  
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   ICS 77.140.15; 91.080.40  
© KEBS 2014 — All rights reserved iii  
 
 
  
 
  
 
 
  
 
  
High yield steel bars for the reinforcement of 
concrete — Specification 
 
 
 
  
 
  
 
 
  
 
  
 
  
KENYA BUREAU OF STANDARDS (KEBS) 
 
Head Office:  P.O. Box 54974, Nairobi-00200, Tel.: (+254  020) 605490, 602350, Fax: (+254 020)  604031 
E-Mail: info@kebs.org,  Web:http://www.kebs.org   
 
Coast Region    Lake Region         Rift Valley Region  
P.O. Box 99376, Mombasa-80100  P.O. Box 2949, Kisumu-40100       P.O. Box 2138, Nakuru-20100 
Tel.: (+254  041) 229563, 230939/40 Te l.: (+254 057) 23549, 22396       Tel.: (+254 051) 210553, 210555  
Fax: (+254  041) 229448   Fax: (+254 057) 21814 
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iv         © KEBS 2014 — All rights reserved Foreword 
 
This Kenya Standard was prepared by the Steel Technical Committee under the guidance of the Standards 
Projects Committee and it is in accordance with the procedures of the Kenya Bureau of Standards. 
 In Kenya, high tensile steel for the reinforcement of conc rete mainly comes in the form of cold-twisted square 
bars. However, hot-formed deformed bars are steadily  gaining ground in this field, and this issue addresses 
this changing trend. 
 This edition of the standard also aims at making the steel bars easily traceable to the manufacturers, thus 
introducing a measure of enhanced quality control into the industry. The bars will also be more easily 
identified by the sizes as a result of the incorporated colour coding requirement, thus assisting the general public while purchasing the steel. 
 
In formulating this standard, due consideration was given to experiences gained in the use of other Kenya Standards on steel reinforcement, especially KS 02-22, Specification for hot-rolled mild steel bars for 
reinforcement of concrete. 
 During the preparation of this standard, reference was made to the following documents: 
 
BS 4449, Carbon steel bars for the reinforcement of concrete.  
SABS 920, Steel bars for concrete reinforcement. 
 The assistance derived from these sources is hereby acknowledged. 
 
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KENYA STANDARD           KS 573:2014 
 
 
© KEBS 2014 — All rights reserved   1  
High yield steel bars for the reinforcement of concrete — 
Specification  
 
 
 
1 Scope 
 This Kenya Standard specifies requirements for rolled steel bars, other than plain round bars, for use in the 
reinforcement of concrete. It does not cover steel for pre-stressing concrete.  
2 Normative references 
 
The following normative documents contain provisions which, through reference in this text, constitute 
provisions of this KS 573.  For dated references, subsequent amendments to, or revisions of, any of these 
publications do not apply.  However, parties to agreements based on this KS 573 are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below.  
For undated references, the latest edition of the normative document referred to applies. 
 KS 02-18, Specification for steels for building construction 
 
KS 06-141, Specification for tensile testing – Part 1: Steel in general 
 
3 Terms and definitions 
 
4 Physical requirements 
 
For the purposes of this standard, the following definitions shall apply: 
  
3.1 
bar 
a steel product of any form of cross section, as-rolled, including a rod of steel 
 
3.2 cold-worked deformed bar   
a bar which has been cold-worked to comply with the  property requirements of this standard 
 
3.3 
nominal size   
the diameter of a circle with an area equal to the effective cross-sectional area of the bar, in accordance with 
4.1 and 4.4 
 
3.4 
nominal density   
the value of 0.00785 kg/mm2 per metre run, taken for purposes of converting a length and cross-sectional 
area of a bar to its mass, as described in 4.5 
 
3.5 
yield stress   
the stress at which a marked increase in deformation of the specimen occurs without increase of load during 
a tensile test 
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2         © KEBS 2014 — All rights reserved 3.6 
proof stress 
the nominal stress that produces a non-proportional elongation equal to a specified percentage (0.2% for  this 
standard) of the extensometer gauge length as deduced from a load-extension diagram or a stress-strain 
diagram  
 
3.7 
characteristic strength 
the value of yield strength, having a prescribed probab ility of not being attained in a hypothetical unlimited 
test series. The characteristic value is the lower limit of the one sided statistical tolerance interval at which 
there is a 90% probability (i.e. 1 - α = 0.90) that 95% (p = 0.95) of the values are at or above this lower limit; 
this definition refers to the long-term quality level of production  
 
3.8 
tensile strength  
the ultimate tensile stress obtained from the stress/strain curve 
 
3.9 
batch    
any quantity of bars of one size and material type, whether in coils, or in bundles, presented for examination 
and testing at any one time 
 
3.10 
longitudinal rib   
a uniform continuous rib parallel to the axis of the bar 
 
3.11 
length  
a piece of nominally straight bar cut to a specified length 
 
3.12 
transverse rib 
any rib on the surface of a bar other than a longitudinal rib 
 
3.13 
hot rolled deformed bar 
a bar that has been so shaped during ho t rolling that it conforms to either the geometrical or the performance 
test classification given in 4.7 
4 Physical requirements 
4.1 Standard/Nominal size 
4.1.1 Nominal sizes  
The nominal size of bars given in Table 1 shall be the standard sizes. 
Table 1 — Standard sizes 
 
Nominal size , 
mm 8 10 12  16 20 25 32 40 
NOTE   Only sizes given in Table 1 shall be allowed for manufacture. 
 
 
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© KEBS 2014 — All rights reserved 3 4.1.2 Tolerance 
The deviation of any cross-sectional dimension from its nominal size (other than those of ribs), shall not 
exceed 8 %. 
 
4.2 Lengths 
4.2.1 Standard lengths 
Steel supplied in accordance with this standard shall be supplied in lengths of 12 m or 6 m and shall be cut 
to within +100, -0 mm.    
 
4.2.2 Specified lengths 
When bars of specific lengths are required, the actual length shall be at least equal to the specific value and 
shall not exceed that value by more than 50 mm.  
4.3 Nominal cross-sectional area and nominal mass 
The nominal values for the cross-sectional area and mass of individual bars shall be as given in Table 2.  
 
Table 2 — Cross-sectional area and mass 
 
Nominal size 
(mm) Cross-sectional area  
(mm2) Mass per metre  
(kg) Mass for full bar 
(12 m) 
(kg) Mass for full bar 
(6 m) 
(kg) 
8 50.3 0.395 4.74 2.37 
10 78.5 0.616 7.39 3.70 
12 113.1 0.888 10.66 5.33 
16 201.2 1.579 18.95 9.47 
20 314.2 2.466 29.59 14.80 
25 490.9 3.854 46.25 23.12 
32 804.2 6.313 75.76 37.88 
40 1 256.6 9.864 118.39 59.18 
 
4.3.1 The tolerance on mass per meter run shall be as specified in 4.5.2.  
4.3.2 All steel covered by this standard shall be sold or purchased per kilo. 
4.4 Effective cross-sectional area of deformed bars 
4.4.1 Uniform cross sectional area  
For bars whose pattern of deformation is such that, by visual inspection, the cross-sectional area is 
substantially uniform along the length of the bar, the effective cross-sectional area shall be the cross-
sectional area determined by weighing and measuring to a precision of  0.5 %, a length of not less than 0.5 
m when: 
Effective cross-sectional area (in mm2) = 
LW
 85 0.007 
where, 
W is mass (in kg), and 
L is length (in m). 
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4         © KEBS 2014 — All rights reserved 4.4.2 Variable cross sectional area 
4.4.2.1 For a bar where the cross-sectional area varies along its length, a sample not less than 0.5 m 
long shall be weighed ( W) and measured to a precision of ± 0.5 % in the as-rolled condition, and after the 
transverse ribs have been removed, it shall be re-weighed ( W1). 
4.4.2.2 Where the difference between the two masses (W-W 1) is less than 3 % of W1, the   effective 
cross-sectional area shall be obtained as in 4.4.1. 
4.4.2.3 Where the difference is equal to or greater than 3 %, the effective cross-sectional area (in mm2) 
shall be taken as:  
LW
 85 0.007 03.11 
where, 
W1 is mass of the bar with transverse ribs removed (in kg), and  
 
L is length of the bar (in m). 
 
4.4.2.4 For routine test purposes, a nominal ratio of effective cross-sectional area to gross cross-
sectional area of bars covered by 4.4.2.3 shall be stated by the manufacturer and used when testing 
samples.  
4.5 Mass 
4.5.1 For purposes of checking tolerances, the nominal density of steel shall be used (see 3.4). 
4.5.2 The mass per metre run of a bar, when determined in accordance with 4.4.1, shall not differ from 
the nominal value by more than the appropriate tolerance given in Table 3, Column 2.  
4.5.3 The actual batch mass of a consignment of bars shall be equal to the value stated in the relevant 
consignment details subject to the appropriate tolerance given in Table 3, Column 3. 
 
 
 
Table 3 — Testing tolerances on nominal mass 
 
Nominal size  
(mm)  Tolerance on nominal mass per metre run 
Individual bar 
(%) Batch 
(%)
(1) (2) (3) 
8  6.0 + 4.5 
– 3.5 
10 and over  4.0  2.5 
 
 
4.6 Finish 
 
All bars shall be cleanly rolled and shall be free from harmful defects such as surface flaws, rolling defects, 
piping, foreign bodies and mill sc ales which cannot be removed by manual wire brushing.  
 
Rust, seams, surface irregularities, or mill scale shall not be cause for rejection, provided the weight, 
dimensions, cross-sectional areas and tensile properties  of a hand wire brushed test specimen are not less 
than the requirements of this specification. 
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© KEBS 2014 — All rights reserved 5 4.7 Bond classification 
 
4.7.3 General 
 
Deformed bars shall be classified as Type 1 or Type 2 as follows: 
 
a) in accordance with their surface shape, as specified in 4.7.2; or 
 
b) if the shapes are not applicable, in accordance with their bond performance as in 4.7.3.  
 
4.7.4 Classification by shape 
Type 1  — Either a plain square twisted bar or a plain chamfered square twisted bar, with a pitch of twist not 
greater than 14 times the nominal size of the bar. 
Type 2  —  A bar with transverse ribs at substantially uniform spacing, and with the following properties: 
i) Spacing of ribs not greater than 0.8 Ø for as-rolled deformed bars or 1.2 Ø for cold-formed bars;  
 
ii) The mean cross-sectional area of ribs (measured above the core) in a unit length of bar shall be not 
less than 0.15 Ф mm2/mm, where Ф is the nominal bar size.  
 
NOTE   Recommended formulae for calculation of the projected rib area are given in Annex B.  
 
4.7.5 Classification by performance 
The performance tests described in Annex A shall be conducted by an approved testing authority. The 
classification shall be established as final. 
  
NOTE    For the purposes of this standard, approved testing authorities are Kenya Bureau of Standards Laboratories and any other 
relevant laboratories operating under its accreditation scheme.  
 
4.8 Tensile properties 
The tensile strength of the steel, when tested according to 7.3, shall comply with at least one of following two 
requirements: 
 i)  The tensile strength shall be at least 10 % greater than the actual yield stress measured in the 
tensile test. 
 ii)  The tensile strength shall be between 5 % and 10 % greater than the actual yield stress measured in 
the tensile test. In this case, the actual yield stress shall be not less than B(2.1 - A) N/mm
2, where A 
is the ratio of measured tensile strength to the actual yield stress and B = 460 for bars of nominal size 8 mm to 16 mm or 425 for bars of nominal size over 16 mm. 
 
The elongation of the steel complying with this standard shall be as given in Table 4. 
  
Table 4 — Tensile properties 
 
Nominal size of bar Specif ied characteristic strengthMinimum elongation on 
gauge length lo 
(mm) (N/mm2)( % )  
8 up to and includin g 16  460 12 
Over 16   425   14 
NOTE   lo is the gauge length = 5.65oSwhere So is the original cross-sectional area of the test piece. 
 
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6         © KEBS 2014 — All rights reserved 4.9 Resistance to cold bending 
 
4.9.1 Bending   
 
When tested according to 7.4, a bar shall show no sign of fracture or irregular bending deformation.  
 
4.9.2 Re-bending 
 
When tested according to 7.5, a bar shall show no sign of fracture or irregular bending deformation. 
 
4.10 Specified characteristic strength 
 
4.10.1 The specified characteristic strength ( see 3.7) of bars complying with this standard is given in 
Table 4.  
4.10.2 The steel shall be considered to comply with the specified characteristic strength in Table 4 
provided that, for each size and type of bar.  
i) not more than two results of yield stress out of the last 40 consecutive results are less than the 
specified characteristic strength. 
 ii)  no routine test results are less than 0.93 of the specified characteristic strength. 
 
When a new type of size of bar is introduced, 4.10.2 i) shall apply to any number of tests until the first 40 
have been accumulated. 
 
5 Process of manufacture 
 
The manufacture of steel that complies with this standard shall be in accordance with KS 02-18. 
 
6 Product identification, delivery and marking 
 
6.9 Marking 
 
6.9.1 As an indication of the size, each bar shall bear a colour code in the form of a single lateral colour 
strip, of not less than 25 mm wide, at each end of the bar. The colours shall vary according to the bar sizes as given in Table 5. 
Table 5 — Colour codes 
 
Nominal size  
mm 8 10 12  16 20 25 32 40 
Colour code Yellow Blue Red Green Orange Purple White Brown 
 
 
6.9.2 Each bar shall be indelibly branded at one or more points along its length with the name and/or 
registered trademark of the manufacturer. 
 
6.10 Defects revealed after delivery 
 
Should any or all material after delivery be found not to be in accordance with this specification, such 
material shall be deemed not to comply with this Kenya Standard. However, notwithstanding any previous acceptance, material delivered, which does not comply  with this standard due to bad bending, chemical 
exposure, heating etc. while on transit or on site, shall not be cause for the manufacturer's liability. 
  
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© KEBS 2014 — All rights reserved 7 6.11 Storage  
 
To minimize rust and other natural effects of exposure to the atmosphere, steel shall be stored in a dry and 
cool environment. 
 
6.12 Labelling 
Each delivery dispatched from the rolling mill shall be accompanied by a delivery note that bears clearly the 
following information: 
i) The manufacturer’s name and/or trade mark; 
ii) The type of bars as per 4.7; 
iii) The nominal size of the bars; 
iv) The standard lengths of the bars; 
v) The number of bars in the delivery; and 
vi) The number of this Kenya Standard. 
 
6.5  Bar marking 
 
Each bar shall be indelibly and legibly engraved/embossed at least once in every 1.5 metre length with the registered trade mark. 
7 Inspection and test methods 
7.1 Inspection and sampling 
7.1.1 Routine testing and inspection  
All materials shall be subject to routine inspection and testing by the manufacturer or supplier in accordance with 7.1.2
 of this standard, and a record of the test result s of material conforming to this standard shall be 
kept by the supplier in a form similar to that given in Annex C. Test specimens shall be either at least 600 
mm long or 20 times the nominal size, whichever is greater.  
7.1.2 Purchaser's test  
7.1.2.1 In the circumstances where a purchaser requires to verify that the specified characteristic strength is 
attained by a batch of steel, he shall first agree with the supplier at what establishment the steel shall be 
tested. Test results from any other establishment shall not be used. In all cases, an averaging extensometer 
shall be used. 
7.1.2.2 Ten test specimens shall be selected from different bars in the batch. 
7.1.2.3 Where the purchaser is satisfied that routine testing has been carried out, he may use an alternative 
abbreviated purchaser's test as follows: 
Three test specimens shall be selected from different bars in the batch. If any one test result is less than 93 
% of the specified characteristic strength, the requirements of 7.1.2.2 shall apply. If the three valid test results have a yield stress equal to or greater than th e specified characteristic strength the batch shall be 
deemed to comply with this standard in respect of the specified characteristic strength requirements. 
7.1.2.4 Test samples, of sufficient length, for the specified tests shall be selected from each batch at a 
frequency not less than that specified in Table 6; except  that if a batch comprises bars less than the quantity 
specified in Table 6, at least one test sample shall be selected to represent a day's production. 
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8         © KEBS 2014 — All rights reserved Table 6 — Frequency of testing, and bend test 
  
Nominal size 
(mm)  Quantity
Under 10 
 
10 to 16 inclusive  
 Over 16 
 1 sample from each 25 000 kg or part thereof 
 
1 sample from each 35 000 kg or part thereof 
 
1  sample from each 45 000 kg or part thereof 
  
7.2 Preparation of test pieces 
7.2.1 The tensile, bend and re-bend tests shall normally be carried out on straight bars as produced, 
without machining. 
 
7.2.2   In order to simulate natural ageing, test samples may be subjected to a temperature of 100 oC for a  
period of not more than 2 h provided that the tensile, bend and re-bend test samples are so treated and the 
fact is recorded on the test sheets and certificates. No  other form of heat treatment shall be permissible. 
 
7.3 Tensile test 
7.3.1 The tensile strength, yield stress and the elongation  of the steel shall be determined in accordance 
with KS 06-141 and shall comply with the requirements specified in 4.8 of this standard. The rate of loading when approaching the yield stress shall not exceed 10 N/mm
2 per second.  
7.3.2 For routine testing, the yield stress may be taken as the stress at which elongation first occurs in the 
test piece without increasing the load during tensile test. In case of steels with no such definite yield point, 
the proof stress is the stress under the prescribed testing conditions at which the observed increase in the gauge length is 0.5 % of the gauge length when the rate at which the load applied is not more than 10 
N/mm
2 per second. 
7.3.3 The stresses shall be calculated using the cross-sectional area of the bar tested. The effective cross-
sectional area shall be determined as in 4.4. 
7.4 Bend test 
7.4.1 The bend test shall be carried out: 
i) on a test piece having a temperature of between 5 oC and 35 oC. 
ii) with apparatus that ensure  
 
— close contact between the test piece and the mandrel 
 
— a continuous and uniform production of bending deformation at every section of the bend. 
iii) on a test piece which is adequately supported by plain smooth surfaces or rolls which do not offer 
resistance to longitudinal movement of the test piece. 
 
 
7.4.2 The test piece shall be bent through 180o round a mandrel of a diameter six times the nominal size 
of the bar under test.   
7.4.3 Failure is indicated if the bar fractures completely or cracks at the bend are visible to the naked eye.  
 
7.5 Re-bend test 
 
7.5.1 The test shall be carried out in the following manner: THE STANDARD HAS BEEN WITHDRAWNOrder # NUMBER/Downloaded:Single-user licence only, copying and networking prohibited.KS 573: 2014 
 
© KEBS 2014 — All rights reserved 9 i)  the test piece shall be bent, under the conditions of the bend test, through 45o round a mandrel of a 
diameter equal to five times the no minal size of the bar under test; 
ii)  it shall then be subjected to a temperature of 100 oC for not less than 30 min, as a  result of 
immersion in boiling water; 
iii)  when the test piece has cooled to a temperature between 5 oC and 35 oC, it shall be bent back 
(partially re-straightened) by a steadily applied force through at least 23o on the same bending 
machine as used in i) above. The rate of application of the load shall not exceed 3 r/min or equivalent. 
7.5.2 Failure shall be indicated if the bar fractures completely, or cracks at the bend are visible to the 
naked eye. 
7.5.3 In the event of failure, if there is any damage to the ribs, caused by carrying out the initial bending, 
the test shall be deemed invalid. 
NOTE  Damage to the ribs can be avoided by the use of an aluminium sheet insert placed between the specimen and the former. 
The aluminium sheet shall have a maximum thickness of 6 mm. 
 
 
  
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10         © KEBS 2014 — All rights reserved Annex  A 
(normative) 
 
Performance test for deformed bars  
 
A.1 The principle of the test is to show that deformed bars, claimed to be equal to those satisfying the 
classification in 4.7.2, will hold for a given time the specified characteristic strength in a pull-out test with a 
free end slip not greater than 0.2 mm. 
 
A.2 For a range of sizes of bar which are geometrically similar in shape, tests shall be carried out on two 
sizes, preferably 20 mm and the largest available size. The surface shape of the bars to be tested shall 
comply with the manufacturer's published specification, and shall be as near to the minimum amount of 
deformation as is possible. Six specimens of each size shall be tested. The surface condition of the bar shall 
be no more than lightly rusted.  
A.3 The test prisms shall have a square cross section of 150 mm side for bars up to 20 mm size and 250 
mm side for bars over 20 mm size.   
   
The length of the prism l, in millimetres, shall be calculated as follows:  
   
l  =   21yf
mm for deformed Type 1 bars, and  
  
   
l  =  28yf
mm for deformed Type 2 bars 
 
where, 
fy  is the specified characteristic strength of the steel (in N/mm 2), and  
 
  is the nominal bar size (in mm).  
 
A.4       The test bar shall be rigidly embedded and cast vertically in, and pass completely through, the prism 
of concrete along its longitudinal axis. The prism shall be reinforced with a helix of 6 mm  diameter plain mild 
steel at 25 mm pitch along the embedded length . The outer diameter of the helix shall be 5 mm less than the 
side of the square cross section. A suitable mould is shown in Figure A.1. 
   
A.5 At the time of the pull-out test the concrete cube strength shall be between 40 N/mm2 and 45 N/mm 2. 
   
A.6 The test piece shall be mounted in a suitable testing device in such a manner that the bar is pulled 
axially from the prism. The end of the bar at which the pull is applied shall be that which projected from the top end of the prism as cast. Plaster bedding rubber or plywood packing shall be placed between the top end 
of the prism and the surface of the testing device bearing on it. 
    A suitable dial gauge shall be mounted in such a manner that
 the gauge records the relative slip between the 
unloaded end of the bar and the bottom end of the prism as cast. 
   
A.7 During a period of approximately 2 min, the axial load  in the bar shall be increased steadily until the 
tensile stress in the bar attains the specified characteristic strength fy for the grade of steel from which the 
bars are made. This stress shall be held constant for a further 2 min after which the length of the free end 
slip of the bar shall be recorded. 
   
A.8 If the average free end slip of the six bars tested exceeds 0.2 mm they  shall not qualify for the 
classification in 4.7.2. 
   
A.9 The test report shall include measurements which define the  deformation of the bars tested. THE STANDARD HAS BEEN WITHDRAWNOrder # NUMBER/Downloaded:Single-user licence only, copying and networking prohibited.KS 573: 2014 
 
© KEBS 2014 — All rights reserved 11 
 
 
 
Figure A.1 — Typical mould to be used for bond test 
 
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12         © KEBS 2014 — All rights reserved Annex B 
(informative) 
 
Recommended formulae for calculating projected rib area 
 
 
The projected rib area R, in millimetres squared per mill imetre length of bar, should be calculated for ribbed 
bars using one of the following equations:  
a) for as-rolled deformed bars: 
 


csin   tlhnR  
 
b) for cold twisted bars: 
 





p  sin   1 Nh
clhnRt 
 
where, 
 
n  is the number of rows of transverse ribs (see note 1); 
l  is the length of the transverse rib (mm) (see note 2); 
ht  is the height of the transverse rib (mm) (see note 3); 
β  is the angle between the center line of the transverse rib and the bar axis (o); 
c  is the centre to centre spacing between transverse ribs (mm) (see note 4); 
N  is the number of longitudinal ribs; 
h1  is the height of the longitudinal rib (mm) (see note 5); 
p  is the pitch of twist measured parallel to the bar axis (mm) (see note 6); 
φ  is the nominal bar size. 
 
NOTE 1  If more than one pattern of transverse ribs exists, e.g. alternate ribs are set at different angles, or there are different rib  
patterns in each row, the term containing n should be calculated for each different set of ribs, and the summation of values ob tained.  
NOTE 2  The length of the transverse rib is measured at the rib to core interface. The length should be determined as the average of 
three measurements on each row or set of transverse ribs.  
NOTE 3  The height of the transverse rib is measured perpendicular to the core of the bar. The height should be determined as the 
average of three measurements on each row or set of transverse ribs. (Using Simpson’s rule for approximation under a curve, wit h rib 
height measurements at the mid and quarter points, the rib height for each rib profile may be established as a proportion of it s mid point 
height. For transverse ribs of parabolic profile, the rib height should be taken as two thirds of the mid point height).  
NOTE 4  The centre to centre spacing between transverse ribs is determined by dividing the distance, measured parallel to the axis of 
the bar, between the mid points of two ribs, of about ten ribs apart, by the number of rib spaces in between. For twisted bars,  the rib 
spaces should be counted in a helical fashion.  
NOTE 5  The height of the longitudinal rib is determined as the average of three measurements on each rib.  
NOTE 6  The pitch of twist measured parallel to the bar axis is determined as the average of three measurements.  
 
  
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© K E B S  2 0 0 8  —  A l l  r i g h t s  r e s e r v e d                  1 3    
Annex C 
(normative) 
 
Test results 
 
C.1  Tensile test results  
 
Customer: Test certificate No. 
Material: Rate of loading: 
 
 
Sample Specified characteristic strength 
Ultimate tensile Increase 
from 
yield 
  Gauge length Elongation 
L
O 
 
  
Strength Requirement  
No. Size 
mm Load 
kN Stress 
N/mm2 Load 
kN Stress 
N/mm2 Specified 
N/mm2  
0.93 
min. 
N/mm2 Load 
kN Stress 
N/mm2 Per cent Initial 
mm Final 
mm Extn. 
mm Per 
cent Remarks 
                
                
                
 
 
 
  
 
  
 
 THE STANDARD HAS BEEN WITHDRAWNOrder # NUMBER/Downloaded:Single-user licence only, copying and networking prohibited.KS 573: 2014 
 
1 4                 ©  K E B S  2 0 1 4  —  A l l  r i g h t s  r e s e r v e d   
C.2 Physical test results 
 
 
Sample Length Area Mass Mass per M Variation Aver. 
Var Permissible 
variation Bend 
Test Re-bend Other 
Remarks 
No. Size 
mm Section 
shape m Nominal 
mm2 Actual 
mm2 kg Nominal 
kg Actual 
kg kg % % % %    
                 
                 
                 
                 
                 
                Operator 
                Checked 
 
 THE STANDARD HAS BEEN WITHDRAWNOrder # NUMBER/Downloaded:Single-user licence only, copying and networking prohibited.KENY A BUREA U OF S TAND ARDS (KEBS)
KEBS CER TIFIC ATION MARKS
1. Product Cer tification Mar ks
Diamond Mark of Quality
 SYMB OL FOR PR ODUCT QU ALIT Y EX CELLENCEStandardization Mark
 SYMB OL FOR PR ODUCT QU ALIT Y
2. Systems Cer tification Mar ks
ISO 9001 REGISTERED FIRM
QUALIT Y MAN AGEMENT SYS TEM
ISO 22000 REGISTERED FIRM
FOOD & S AFET Y MAN AGEMENT SYS TEMISO 14001 REGISTERED FIRM
ENVIRONMENTAL MANAGEMENT SYSTEMKEBS is mandated to provide Standardization,
Metrology and Conf ormity Assessment Ser vices
through:
•  Promotion of standardization in commerce and industry
•  Provision of testing and calibration facilities
•  Control of the use of standardization marks
•  Undertaking educational work in standardization
•  Facilitation of the implementation and practical application of standards
•  Maintenance and dissemination of the International System of
    Units (SI) of measurements
KEBS of fers the f ollowing ser vices:
•  Standards development and harmonization
•  Testing services
•  Measurement services (Calibration)
•  Enforcement of standards
•  Product inspection services
•  Education and Training in Standardization, Metrology and Conformity Assessment
•  Product and Management Systems Certification Services
  For further Information please contact
The Managing Director
Kenya Bureau of Standards
Popo R oad, Of f Mombasa R oad
P.O. Box 5 497 4 - 00200
NAIROBI, KENYAImpor t Standar dization Mar k
 SYMB OL FOR PR ODUCT QU ALIT YKEBS Standardization Mark (S-Mark) is issued
for use on products that comply with the minimum
quality requirements prescribed in Kenya
standards. It uses standards as a benchmark for
quality compliance and aims at giving
manufacturers improved market  access and also
giving consumers an assurance of quality for the
products bearing the mark.
OCCUP ATION AL HEAL TH AND S AFET Y
OHSAS 18001INFORMA TION ON ST ANDARDS
Standards are documents that provide a common reference point for the assess-
ment of the quality of goods and services. Standards facilitate tranparency in the
exchange of products and enhance market access of Kenyan products into local,
regional and international markets.
Information on standards and related documents is available at the KEBS stan-
dards information centre.
KEBS houses the WTO-TBT National Enquiry Point (NEP) which disseminates
notification likely to af fect international trade to the industry .
KEBS also provides technical advice on installation and improvement of quality
goods and services to the industry so as to facilitate efficient implementation of
standards. Some of the advantages of standards include: enhancement of quality
assurance, safety and environmental protection measures, minimization of wast-
age, reduction of costs and unecessary varieties and promotion of interchange-
ability and increased productivity in industry .
Tel.: +25 4 (0) 20 69 48000
Fax: +25 4 (0) 20 60 403 1
E-Mail: info@kebs.org
E-Mail: customercare@kebs.org
Website: http://www.kebs.orgTHE STANDARD HAS BEEN WITHDRAWNOrder # NUMBER/Downloaded:Single-user licence only, copying and networking prohibited.