©KEBS 2017 — All rights reserved  1 `                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   
KENYA STANDARD                                                                                                                                                                                                         KS:2712 : 2017         
                    
 
 
 
 
 
 
 
 
 
 
 
 
 
       Steel for the  reinforcement of  concrete — 
Weldable  reinforcing steel — Bar, coil and 
decoiled  product — Specification    
 
       
 
 
 
 
 
 
 
 
 
© KEBS 20 1 7                                                                                                              First Edition 20 17 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 KS 2712: 2017      
 TECHNICAL COMMITTEE REPRESENTATION  
 
The following organizations were repr esented on the Technical Committee:  
1. Architectural association of Kenya  
2. Blue Nile group of companies   
3. Brollo Kenya Limited  
4. Consumer Information Network  
5. Dedan Kimathi University Of Technology \ 
6. Devki Steel Mill Ltd  
7. Doshi & co(H) Ltd  
8. Howard Humphreys  
9. Insteel L imited  
10. Kenya Association of manufacturers  
11. Kenya Institute of Research and development   
12. Kenya National Accreditation Services     
13. Nails and Steel Products  
14. National Housing Corporation  
15. Palak international limited  
16. Steel Makers Ltd  
17. Tononoka Steels  
18. University  of Nairobi  
19. 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 Mana ging Director, Kenya Bureau of Standards, are 
welcome.  
 
 
 
 
 
 
 
 
© Kenya Bureau of Standards, 201 6 
 
Copyright. Users are reminded that by virtue of Section 25 of the Copyright Act, Cap. 12 of 2001  of the Laws of 
Kenya, copyright subsists in all Kenya Standa rds 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 writing from the Managing D irector . 
 
. 
 
 
 
 
 
 
 
 
 
                                                   
 
 
           
 
     
©KEBS 2017 — All rights reserved  3    
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Steel for the reinforcement of concrete 
— Weldable reinforcing steel — Bar, 
coil and decoiled product — 
Specification   
 
 
 
 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
KENYA B UREAU 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                                 Tel.: (+254 057) 23549, 22396                                                                 Tel.: (+254 051) 210553, 210555  
Fax: (+254  041) 229448                                                                                                            Fax: (+254 057) 21814  KS 2712: 2017      
 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 Burea u of Standards.  
 
Reference has been made from BS 4449 -1:1988: Steel for the reinforcement of concrete — Weldable 
reinforcing steel — Bar, coil and decoiled product — Specification    
©KEBS 2017 — All rights reserved  5  
 
 
Steel for the reinforcement of concrete — Weldable reinforcing steel — 
Bar, coil and decoiled product — Specification  
 
1.   Scope  
 
This Kenya Standard specifies requirements for ribbed weldable reinforcing steel used for the  reinforcement of 
concrete structures. The standard covers steel delivered in the form of bars, coils an d decoiled products. The 
standard contains provisions for three steel grades, all of 500 MPa characteristic  yield strength, but with 
different ductility characteristics. The three grades are B500A, B500B and B500C.  
 
The weldability requirements for all gra des of steel are specified in terms of the chemical composition, and  in 
particular the carbon equivalent value.  
 
Steel bars produced by re -rolling finished products, or by rolling material of which the metallurgical history  is not 
fully documented or not k nown, are not covered by this Kenyan  Standard.  
 
NOTE Flash welds in lengths of bar are permissible under this standard, provided all the mechanical requirements are met.Howe ver, for 
some purposes, purchasers might specifically require bars without flash we lds, and if so this ought to be stated at the  time of enquiry 
and/or order  
 
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 r eferences, the latest edition of the  referenced document 
(including any amendments) applies. Information on currently valid national  and international standards can be 
obtained f rom the Kenya Bureau of S tandards .  
 
BS EN 1766:2000 , Products and systems for  the protection and repair of concrete structures — Test methods  
— Reference concretes for testing.  
BS EN 10080:2005 , Steel for the reinforcement of concrete — Weldable reinforcing steel — General.  
BS EN 12390 -3, Testing hardened concrete — Part 3: Compres sive strength of test specimens.  
ISO 15630 -1:2002 , Steel for the reinforcement and prestressing of concrete — Test methods — 
Part 1: Reinforcing bars, wire rod and wires .  
 
3. Terms and definitions  
For the purposes of this Kenyan Standard, the following terms  and definitions apply.  
 
3.1.   
reinforcing steel  
steel product with a circular or practically circular cross -section which is suitable for the reinforcement of            
concrete    
                      
 NOTE The reinforcing steels specified using this standa rd are bar, coil and decoiled product.  general purpose use  conditions 
corresponding to service class 3 of ENV 1995 -1-1:1993 which is characterised by climatic conditions leading to higher moisture contents 
than in service class 2 [EN 13986:2002]  
3.2.  
ribbed re inforcing steel  
reinforcing steel with at least two rows of transverse ribs, which are uniformly distributed over the entire length  
 
3.3.  
longitudinal rib  
      uniform continuous protrusion parallel to the axis of the reinforcing steel  
3.4.  
load duration class   
class characterized by the effect of a constant load acting for a certain period of time in the life of the structure  
 KENYA STANDARD  KS 2712: 2017      
 NOTE 1 The load duration classes are defined in EN 1995 -1-1, see Table 1.  
 
3.5.   
rib height  
h 
distance from the highest point of the rib (tra nsverse or longitudinal) to the surface of the core, to be measured 
normal to the axis of the reinforcing steel  
3.6.  
rib spacing  
c 
distance between the centres of two consecutive transverse ribs measured parallel to the axis of the reinforcing 
steel  
3.7.  
angle of transverse rib inclination  
ʙ 
angle between the axis of the transverse rib and the longitudinal axis of the reinforcing steel  
 
3.8.  
α 
angle of the rib flank measured perpendicular to the longitudinal axis of the rib  
NOTE See Figure 1.  
 
3.9.  
relative rib area  
fR 
area of the projection of all ribs on a plane perpendicular to the longitudinal axis of the reinforcing steel divided 
by the rib spacing and the nominal circumference  
 
3.10.  
bar 
ribbed reinforcing steel manufactured in straight lengths  
3.11. 
coil 
single length of reinforcing steel wound in conce ntric rings  
 
3.12. 
decoiled product  
reinforcing steel manufactured in coils and subsequently straightened for further processing  
 
3.13. 
An 
cross -sectional area equivalent to the area of a circular plain bar of the same nominal diameter . 
 
3.14. 
characteristic value  
value of a material or product property having a prescribed probability of not being attained in a  hypothetical 
unlimited test series  
 
NOTE 1 This value generally corresponds to a specific fractile of the assumed statistical distribution of the particular prop erty of the 
material or product.  
 
3.15. 
minimum value  
value below which no test result shall fall    
©KEBS 2017 — All rights reserved  7  
 
3.16. 
maximum value  
value which no test result shall exceed  
 
3.17. 
batch  
quantity of bars, coils, or decoiled products of one nominal diameter and one cast produced by one 
manufacturer and presented for examination at any one time  
 
3.18. 
standard property  
property which is part of the routine inspection and test requirements for every test unit  
 
3.19. 
special property  
property which is not determined as part of the routine inspection a nd test requirements for every test unit (e.g. 
fatigue performance)  
 
3.20. 
technical class  
type of reinforcing steel defined by its performance characteristics, identified by a unique product number  
 
4.  Symbols  
A list of symbols used in this standard, reproduced from BS EN 10080:2005, is given in Table 1.  
 
5. Designations  
The products covered by this standard shall be designated with the following information:  
a) description of the product form (i.e. bar, coil, decoiled product);  
b) the nominal dimensions of the prod uct; 
c) reference to this standard, and the grade.  
 
For example, the designation for 40 mm diameter bar in 12 m lengths of grade B500B would be:  ―Bar 40 × 
12000 KS 2712 Grade B500B‖.  
 
Where products that conform to this standard are also required to meet al l of the requirements of  BS EN 
10080:2005, for example for the purposes of Marking , then reference to this standard should  also be made in 
the designation. For example, the designation of the 40 mm bar described above would be:  ―Bar BS EN 10080 
40 × 12000 KS 2712  Grade B500B‖.  
 
6.                Steelmaking and manufacturing processes  
The melting process and type of deoxidation of the steel shall be at the discretion of the steel producer.  The 
manufacturing process for the production of coils and bars shall be  at the discretion of the  manufacturer. It shall 
be reported to the purchaser.  
 
Decoiling of coil material shall be done by a machine made for this purpose.  
 
 
 
 
 
 
 KS 2712: 2017      
  
 
Table 1 — List of symbols  
 
 
 
 
 
7.     Product characteristics  
7.1.     Chemical composition  
The v alues of individual elements and the carbon equivalent shall not exceed the limits given in Table 
2. 
The carbon equivalent value Ceq shall be calculated using the following formula:  
 
Table 1 — List of symbols  
Symbol  Description  Unit  
An  Nominal cross -sectional area  mm2  
Agt  Percentage total elongation at maximum force  %  
c  Transverse rib spacing  mm  
Ceq  Carbon eq uivalent value (CEV)  % by 
mass  
Cv  Specified characteristic value  a  
d  Nominal diameter of the reinforcing steel  mm  
e  Gap between rib rows  mm  
fR  Relative rib area  —  
h  Rib height  mm  
k  Coefficient as a function of the number of test res ults  —  
x  Average value of test results  a  
Re  Yield strength  MPab  
ReH  Upper yield strength  MPab  
Rm  Tensile strength  MPab  
Rm/R e  Ratio tensile strength/yield strength  —  
Rp0.2  0.2 % proof strength, non proportional extension  MPab  
s  Estimate of the standard deviation  a  
µ  Transverse rib flank inclination  degrees  
¶  Angle of transverse rib inclination  degrees  
2Öa  Stress range in the axial load fatigue test  MPab  
Ömax  Specified maximum stress in the fatigue test  MPab  
Ömin  Specified minimum stress in the fatigue test  MPab  
R e,act  Actual value of yield strength  MPab  
R e,nom  Specified value of yield strength  MPab  
R 
e,act/R 
e,nom  Ratio actual value of yield strength/specified value of yield strength  —  
a1, a2, 
a3, a4  Increment for calculation of batch release criteria  a  
b  Width of the beam (beam test)  mm  
dm  Mandrel diameter (beam test)  mm  
Fa  Total force applied (beam test)  kN  
Fi  Force in hinge and bar or wire (beam test)  kN  
Ös  Stress in the b ar or wire (beam test)  MPab  
Ùb  Bond stress (beam test)  MPab  
Ùbu  Bond stress at maximum force (beam test)  MPab  
Ù0.01, 
Ù0.1, Ù1  Bond stress at 0.01 mm, 0.1 mm and 1 mm slip (beam test)  MPab  
a The unit depends on the property. b 1 MPa = 1 N/mm 2 .  
 
   
©KEBS 2017 — All rights reserved  9 Where  
Mn is the percentage manganese content ; 
Cr is the percentage chromium content;  
V is the percentage vanadium content;  
Mo is the percentage molybdenum content;  
Cu is the percentage copper content;  
Ni is the percentage nickel content.  
 
Table 2 — Chemical composition (maximum % by mass)  
 
 Carbona Sulphur  Phosphorus  Nitrogenb Copper  Carbon 
equivalent  
Cast 
analysis  0.22 0.05 0.05 0.012  0.80 0.50  
Product 
analysis  0.24 0.055  0.055  0.014  0.85 0.52 
a It is permitted to exceed the maximum values of carbon by 0.03 % by mass, provided that the carbon equ ivalent value is 
decreased by 0.02 % by mass.  
b Higher nitrogen contents are permissible if sufficient quantities of nitrogen binding elements are present.  
 
 
During product analysis, any bar that falls outside the maximum specified limits in Table 2 shal l be deemed not 
to conform to this Kenya  Standard.  
In cases of dispute, where a product analysis falls outside the maximum limits specified in Table 2, the  
procedure defined in 11.2 shall be applied to determine whether the material conforms to this standa rd. 
 
7.2. Mechanical properties  
NOTE Bars, coils and de -coiled products should be free from features such as seams, porosity, segregation and non -metallic inclusions, 
etc., where they would cause the product to fail to meet the specified mechanical properties."  
 
7.2.1.  General  
The characteristic value is (unless otherwise indicated) the lower or upper limit of the statistical tolerance 
interval at which there is a 90 % probability  (1-μ = 0.90) that 95 % (p = 0.95) or 90 % (p = 0.90) of the values 
are at or above the lower limit or at or below the upper limit respectively. This quality level refers to the long -
term quality level of production.  
 
7.2.2.  Conditions of testing  
The conditions o f testing shall conform to Table 3.  
Table 3 — Conditions of testing the mechanical properties  
 
Manufacturing and delivery condition   Condition of testing   
Produced in straight lengths by hot rolling   As delivereda or agedb  
Produced in straight lengt hs by cold working   Agedb   
Produced as coil and delivered decoiled    Agedb   
Produced and delivered as coil     Agedb KS 2712: 2017      
 a Aged in the case of dispute.  
b Aging method: heat the test piece to 100 °C, maintain at this temperature (±10 °C) for a period of  60 
(+15 –0 min)., and then cool in  still air to room temperature. The method of heating is left to the 
discretion of the manufacturer.  
 
 
 
7.2.3.  Tensile properties  
The specified characteristic values for the tensile properties are given in Table 4.  
Table 4 — Characteristic tensile properties  
 
 
 
The absolute maximum permissible value of yield strength is 650 MPa.  
For yield strength (R e), the upper yield strength (ReH) shall apply. Determine the yield strength (Re) from  the 
0.2 % proof strength (R  p0.2) if a y ield phenomenon is not present.  
 
7.2.4.  Fatigue strength  
7.2.4.1.  General  
Reinforcing bars, coils and decoiled products shall be subject to fatigue testing. When submitted to axial  force 
controlled fatigue testing, using a stress ratio (Ö min./Ö max.) of 0.2, and stress r ange as given in  Table 5, test 
samples shall survive five million stress cycles.  
 
Table 5 — Fatigue test conditions  
   
 
Bar size  
 mm Stress range  
  MPa 
≤16  
>16, ≤20 
>20, ≤25 
>25,   ≤32 
>32  
 
 200   
 185   
 170  
 160  
150   
©KEBS 2017 — All rights reserved  11  
 
7.2.4.2. Bars and coils  
Reinforcing bars from each production site shall be subject to fatigue testing, to determine the fatigue  
characteristics of a pa rticular geometrical shape and process route. The fatigue properties  for each steel  grade 
and process route shall be established at an applicable testing laboratory, initially by testing samples  selected 
from the upper, middle and bottom of the product dia meter range. At least once a year, samples  shall be tested 
from different bars or coils of one diameter from each process route. Test samples shall be  selected so that all 
diameters for each process route shall be tested over a five -year period.  
 
7.2.4.3. Decoiled product  
Decoiled products, from each production site, shall be subject to fatigue testing. Initially, samples shall be  taken 
from each production site from one decoiling machine type from the largest diameter produced. At a  frequency 
of at least once per y ear, samples of one diameter shall be selected for test from each production  site, from 
one decoiling machine. Sampling shall be carried out in such a way that the combination of  material 
manufacturing route, type of decoiler and individual machines are co vered over a five -year period.  
 
7.2.4.4.  Sampling  
Each test unit shall comprise ten test specimens. For each diameter, from each test unit, five bars shall be  
selected for test. The test specimens shall not exhibit isolated defects that are not characteristic of th e product 
from which they are selected.  
 
7.2.4.5.  Retests  
The products shall be deemed to conform to this standard if all five test pieces endure five million stress  
cycles.If one of the five test pieces produces a valid failure, a further five samples from the tes t unit shall be 
tested.  
 
If one of these further samples fails the test, then the material shall be deemed not to conform to this  standard, 
and an investigation shall be carried out and appropriate actions shall be taken. If all five further  test pieces 
endure five million stress cycles, then the material shall be deemed to comply with this  standard.  
 
In the case of any failure, the test shall be considered invalid if it is initiated from a defect unique to the  test 
piece or in the area within 2d of the tes ting machine grips (where d is the nominal bar diameter); in  this case a 
further single test shall be carried out (see ISO15630 -1:2002).  
 
7.2.5.  Bend performance  
Bend performance shall be demonstrated by means of the following rebend test.  
Bend the test pieces th rough an angle of 90°, around a mandrel with a diameter not exceeding those specified 
in Table 6, age the test piece and then bend back by at least 20°.  
After the test, the specimen shall show no sign of fracture or cracks visible to a person of normal or corrected 
vision.  
 
Table 6 — Mandrel diameters for rebend test  
Nominal diameter d, mm  Maximum mandrel diameter  
≤16  4d 
>16  7d 
 
 
 
7.3. Dimensions, mass per metre and tolerances  
7.3.1.  Preferred diameters, nominal cross sectional area and mass per metre  KS 2712: 2017      
  
The range o f nominal diameters shall be 6 mm to 50 mm.  
 
NOTE 1 The preferred millimetre nominal diameters are 8, 10, 12, 16, 20, 25, 32 and 40.  
NOTE 2 If a bar smaller than 8 mm is required, the recommended diameter is 6 mm.  
NOTE 3 If a bar larger than 40 mm is requi red, the recommended diameter is 50 mm.  
 
NOTE 5 If coil or decoiled product smaller than 8 mm is required, the recommended diameter is 6 mm.The values for the nominal  cross 
sectional area and mass per metre of preferred diameters shall be as given  in Table  7. 
 
NOTE 6 The values for the nominal mass per metre are calculated from the values of the nominal cross sectional area on the ba sis that 
steels have a mass of 0.00785 kg/mm2 per metre run.  
 
Table 7 — Nominal cross -sectional area and mass per metre  
 
Nomin al diameter mm  Cross sectional area mm2 Mass Per meter Kg  
6 28.3 0.22 
8 50.3 0.395  
10 78.5 0.617  
12 113 0.888  
14 154 1.210  
16 201 1.580  
18 254 2.000  
20 314 2.47 
22 381 2.990  
25 491 3.85 
28 618 4.840  
32 804 6.31 
36 1019  8 
40 1257  9.86 
45 1592  12.5 
50 1963  15.4 
 
7.3.2.  Tolerances  
The permissible deviation from nominal mass per metre shall be not more than ±4.5 % on nominal  diameters 
greater than 8 mm, and ±6.0 % on nominal diameters less than or equal to 8 mm.  
   
©KEBS 2017 — All rights reserved  13 7.3.3.  Length  
a) The nominal length of bars s hall  be 6 m and 12 meters only and any other less than 6 meters for stocking 
purposes only.  
b)  Length of bars above 12 meters are allowed but should not be stocked by traders.  
 
The permissible deviation from the nominal length shall be +100/ –0 mm; other  tolerances may be agreed at the 
time of enquiry and order.  
 
7.3.4.  Coil mass  
The nominal coil mass shall be agreed at the time of enquiry and order.  
 
7.4. Bond strength and surface geometry  
7.4.1.  General  
Ribbed bars are characterized by their surface geometry, by means of which bond with the concrete is  
achieved.  Bond property requirements of ribbed reinforcing steels according to this standard shall be based on  
surface geometry, or by means of the bond test provided in Annex A; bond property requirements based on  
surface g eometry are preferred. The assessment criteria for the bond tests shall be as given in the  appropriate 
design documents. A suitable means of factory production control based on the control of  surface geometry 
shall be derived from the bond test results.  
 
NOTE Required levels of bond strength, as measured in the bond test in Annex A, are given in BS EN 1992 -1-1:2004, Annex C  
. 
7.4.2.  Surface geometry  
7.4.2.1.  General  
Ribbed steels are characterized by the dimensions, number and configuration of transverse and longitudinal 
ribs. Bars, coils and decoiled products shall have two or more rows of transverse ribs uniformly distributed 
around the perimeter. Within each row the ribs shall be uniformly spaced. Longitudinal ribs can be present or 
not. An example of a ribbed steel is g iven in Figure 1.  
 
 
 
The values for the spacing, height and rib inclination of transverse ribs shall be within the ranges given in  Table 
8. 
 
Table 8 — Ranges for the rib parameters  
 
Rib height, h  Rib spacing, c  Rib inclination, β ¶ 
0.03d to 0.15d  0.4d to 1.2d  35° to 75°  KS 2712: 2017      
  
 
The characteristic relative rib area shall meet the requirements of Table 9. The characteristic values in  Table 9 
are for p = 0.95.  
 
NOTE The methods for the calculation of relative rib area are given in ISO15630-1:2002  
 
Table 9 — Characteristic relative rib area  
Nominal bar size, d  
mm Relative rib area  
d≤6 0.035  
6 < d ≤12  0.040  
d > 12  0.056  
 
 
 
7.4.2.2.  Transverse ribs  
The projection of the transverse ribs shall extend over at least 75 % of the circumference of the  product, which 
shall be calculated from the nominal diameter.  
The transverse rib flank inclination μ shall be greater than or equal to 45°, and the transition from the rib to the 
core shall be radiused.  
 
7.4.2.3.  Longitudinal ribs  
Where longitudinal ribs are prese nt, their height shall not exceed 0.10d, where d is the nominal diameter of the 
product.  
 
8. Evaluation of conformity  
8.1. Routine inspection and testing  
8.1.1.  General  
Reinforcing steels shall be produced under a permanent system of routine inspection and testing, which  shall 
include evaluation of specified properties, as described in 8.1.2 and 8.1.3.  
 
8.1.2.  Sampling and testing of finished products  
8.1.2.1.  Verification of standard properties  
For the verification of standard properties, sampling and testing shall be as specified in 8. 1.2.2 and 8.1.2.3.  
 
8.1.2.2.  Bars and coils  
The test unit shall be the cast or part quantity of the cast.  
The rate of testing shall be as follows.  
a) For chemical composition, one analysis per test unit. The chemical composition (cast analysis) of the  
steel shall have  been determined by the steel producer.  
b) For rebend tests, nominal mass per metre and surface geometry, one test piece per test unit and  nominal 
diameter.  
c) For tensile tests, one test piece per 30 t with at least three test pieces per test unit and nominal  diameter.  
 
Where bars and coils are produced for the manufacture of welded fabric only, one tensile test  piece shall be 
taken per 30 t produced.  Test results shall be evaluated in accordance with 8.1.3.  
 
8.1.2.3. Decoiled products    
©KEBS 2017 — All rights reserved  15 The processor of products in coil shall ensure that the decoiled products continue to meet the specified  
property requirements of the appropriate grade. Inspection and testing of decoiled reinforcing bars shall  include 
as a minimum:  
a) visual inspection for surface geometry damage of every co il processed;  
b) surface geometry measurement on at least one sample per day and produced size;  
c) tensile testing at a frequency of at least one sample per machine type (roller or spinner) per week from  
each of two processed sizes. The sampling shall be such th at all machines and sizes are covered in a 
six month  period. Only one sample shall be taken from each coil.  
Testing may be carried out either by the processor using its own resources (internal or external) or by the  
processor in co -operation with the coil manufacturer. The tests shall not be seen as release tests, but as the  
basis for the assessment of the long -term quality level (LTQL) as described in 8.2.  
 
8.1.3.  Evaluation of test results  
8.1.3.1. Tensile properties  
8.1.3.1.1.  Where the characteristic value C v is specified as a lo wer limit, the results shall be deemed to conform 
to this standard if either:  
a) all individual values are greater than or equal to the specified characteristic value C v; or 
b)  
 
  
where  a1 is 10 MPa for Re, zero for R m/Re and 0 % for A gt, and all individual va lues are greater than or equal to 
the minimum values given in Table 10.  
 
Table 10 — Absolute minimum and maximum values of tensile properties  
Performance characteristic  Minimum value  Maximum value  
B500A  B500B  B500C  B500A  B500B  B500C  
Re, MPa  485 485  485 650  650  650 
Rm/Re  1.03a 1.06 1.13 N/A N/A 1.38 
Agt, % 2.0b 4.0 6.0 N/A N/A N/A 
a 1.01 for sizes below 8 mm.  
b 0.8 % for sizes below 8 mm.  
 
 
 
8.1.3.1.2.  Where the characteristic value C v is specified as an upper limit (i.e. for R m/Re of grade B500C),the 
result s shall be deemed to conform to this standard if either:  
all individual values of R m/Re are equal to or lower than the specified upper characteristic value of 1.35; or  
 
8.1.3.2.  Bend performance, geometry, mass per metre  
In the rebend test, all test pieces shall f ulfil the requirements of 7.2.5.  
If testing the surface geometry, the results shall meet the requirements of 7.4.  
If testing the mass per metre, no individual value shall be outside the tolerances specified in 7.3.2.  
 
8.1.3.3. Retests  KS 2712: 2017      
 If any test specimen fails to meet the yield strength, tensile/yield strength ratio, total elongation at maximum 
force, rebend or rib geometry requirements, two additional test specimens shall be taken from different bars of 
the same batch to undergo tests. If both additional test spec imens pass the retests, the batch shall be deemed 
to conform to this standard. If either of the additional test specimens fails the retests, the batch shall be 
deemed not to conform to this standard.  
 
8.1.4.  Traceability and test reports  
Delivered batches shall b e identifiable and traceable to the manufacturer and to their production data. The 
manufacturer shall establish and maintain the records required and shall identify the products and their delivery 
documentation accordingly.  
For each delivery, manufacturers  shall supply the following information:  
a) the cast number and cast analysis, including all specified elements and elements used for the  
calculation of the carbon equivalent value;  
b) the carbon equivalent value;  
c) the results of the tensile and rebend t ests;  
d) the mass per metre;  
e) the manufacturing process route; and  
f) the rolled on mill mark . 
 
8.2. Assessment of the long term quality level  
8.2.1.  Material produced under a third party product certification scheme  
The results of tests on all test units of continu ous production shall be collated and statistically evaluated for R e, 
Agt, and R m/Re, taking either the number of results corresponding to the preceding six months’ operation or the 
last 200 results, whichever is the greater.  
 
8.2.2.  Determination of the long -term  quality level  
The evaluation shall be carried out per nominal diameter.  
The following requirement shall be satisfied for R e, Agt and R m/Re: 
x – ks ≥ Cv 
where  
x is the average value;  
s is the estimate of the standard deviation of the population;  
k is the c oefficient listed in Table 11 for R e and in Table 12 for A gt and R m/Re; 
Cv is the specified characteristic value.  
The foregoing is based on the assumption that the distribution of a large number of results is normal but  this is 
not a requirement of this st andard. However, the following alternative methods may be used to  establish 
conformity of the production with the requirements of this Kenya  Standard:  
a) graphical methods including control charts;  
b) non -parametric statistical techniques.  
 
8.2.3.  Material not co vered by a third party product certification scheme  
Material not covered by a third party product certification scheme shall be assessed by acceptance tests on 
each batch (see Annex B).  
 
 
 
 
 
Table 11 — Coefficient k as a function of the number n of test re sults (for a reliable failure rate of 5 % [p = 0.95] 
at a probability of 90 %)  
 
 
 
 
   
©KEBS 2017 — All rights reserved  17  
n  k n  k 
5  3.40  30  2.08 
6  3.09  40  2.01 
7  2.89  50  1.97 
8  2.75  60  1.93 
9  2.65  70  1.90 
10  2.57  80  1.89 
11  2.50  90  1.87 
12  2.45  100  1.86 
13  2.40  150  1.82 
14  2.36  200  1.79 
15 2.33  250  1.78 
16  2.30  300  1.77 
17  2.27  400  1.75 
18  2.25  500  1.74 
19  2.23  1000  1.71 
20  2.21  infinity  1.64 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 KS 2712: 2017      
 Table 12 — Coefficient k as a function of the number n of test results ( for a reliable failure rate  
of 10 % [p = 0.90] at a probability of 90 %)  
 
 
n k n  k 
5  2.74  30  1.66 
6  2.49  40  1.60 
7 2.33  50  1.56 
8  2.22  60  1.53 
9 2.13  70  1.51 
10  2.07  80  1.49 
11  2.01  90  1.48 
12  1.97  100  1.47 
13  1.93  150  1.43 
14  1.90  200  1.41 
15  1.87  250  1.40 
16 1.84  300  1.39 
17 1.82  400  1.37 
18  1.80  500  1.36 
19  1.78  1000  1.34 
20  1.77  infinity  1.28 
 
9. Test methods  
The tensile test for the determination of R e, R m/Re and A gt, the rebend test, the axial load fatigue test, the 
measurement of the surface geometry and the determination of the relative rib area f R, the determination of 
deviation from nominal mass per metre and the methods for chemical analysis shall be in accordance with 
ISO15630 -1:2002. See also Table 3.  
 
    NOTE For the rebend test, it is recommended that the bending rate is approximately three revolutions per minute  
 
10. Identification  
10.1.  General  
Each reinforcing steel shall have identification marks to identify the manufacturer, according to the  
requirements of Annex C.    
©KEBS 2017 — All rights reserved  19 Where Marking  is required, product marking shall be in accordance with BS EN 10080:2005  
 
10.2.  Identification of steel grade  
The steel grade shall be identified by the product’s surface features (arrangement of the transverse ribs) as 
follows:  
Grade B500A: bars shall have two or more series of parallel transverse ribs with the same angle of inclination 
and the same direction for each series. An example of rib pattern of grade B500A with four transverse rib 
series is given in Figure 2.  
 
Grade B500B: bars shall have two or more series of parallel transverse ribs. For bars with two or three rib  
series, one of the series shall be at a contrary angle to the others; and for bars with four rib series, two of  
the series shall be at a contrary an gle to the others. An example of rib pattern of grade B500B with four  
transverse rib series is given in Figure 3.  
 
 
Grade B500C: bars shall have the same arrangement of rib series as for B500B. However, in each rib 
series,  the ribs shall alternate between  a higher and lower angle with respect to the bar axis. The difference  
between the angles of the different ribs and the bar axis shall be at least 10°. An example of rib pattern of  
grade B500C with two transverse rib series is given in Figure 4.  
 
11. Verifica tion of properties in the case of dispute  
11.1.  Mechanical properties   
11.1.1.  
Whenever the determination of a property specified in this standard as a characteristic value creates  a 
dispute, the value shall be verified by selecting and testing three test pieces from v arious pieces from the  
batch under examination.  
If one test result is less than the specified characteristic value both the test piece and the test method shall  
be carefully examined. If there is a local fault in the test piece or reason to believe that an  error has 
occurred  in the test, the test result shall be ignored. In this case a further single test shall be carried out.  
If the three valid test results are equal to or greater than the specified characteristic value, the batch shall  
be deemed to confor m to this standard. If not, the requirements of 11.1.2 apply . KS 2712: 2017      
 11.1.2.  If 11.1.1 is not fulfilled, 10 additional test pieces shall be selected from different bars, coils or 
decoiled products in the batch. The batch shall be deemed to conform to this standard if the  average test 
result of the 10 test pieces is higher than the characteristic value and the individual values are higher than 
the minimum and lower than the maximum values given in Table 10. If not the batch is rejected.  
11.1.3. Whenever the determination of rebend  characteristics is a cause for dispute, they shall be verified 
by selecting and testing three specimens from different bars, coils or decoiled products in the batch. If all 
three specimens pass the tests, the batch shall be deemed to conform, otherwise th e batch shall be 
deemed not to conform to this Kenya  Standard.  
11.2.   
If during product analysis, a single sample falls outside the maximum deviation limits for the composition  
range of a specified element, given in Table 2, further samples shall be selected fro m the remainder of the  
batch as follows:  
a) at least two samples from the same cast for delivered masses up to 5 t;  
b) at least five samples from the same cast for delivered masses up to 20 t;  
c) at least eight samples for delivered masses over 20 t.  
If any of the further samples analysed fall outside the maximum product analysis levels given in Table 
2 for any element, the batch shall be deemed not to conform to this standard.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
   
©KEBS 2017 — All rights reserved  21  
 
Annex A (normative)  
Bond test for ribbed  reinforcing steel — Beam test  
A.1 Introduction  
This annex describes a method for testing the bond characteristics for ribbed bars and decoiled products to  
be used as reinforcing steel in concrete structures.  
The beam test is intended to determine the bond  of reinforcing steel and is to serve as a basis for the  
comparison of reinforcing bars and decoiled products of approximately the same bar or decoiled product  
diameter but with different surface configurations.  
The test method is applicable for reinforcin g steel in diameters u32 mm.  
 
NOTE The method is based on the RILEM -Recommendation RC5, Bond test for reinforcement steel [1].  
 
A.2 Principle of the test  
A test beam is loaded by simple flexure until complete bond failure of the reinforcing steel occurs in  both 
half-beams or until the reinforcing steel itself fails. During loading, the slip of the two ends of the  reinforcing 
steel is measured.  
The beam used for the test consists of two parallelepipedal reinforced concrete blocks interconnected at 
the bottom  by the reinforcing steel of which the bond is to be tested, and at the top by a steel hinge. The  
dimensions of the two blocks and the hinges are determined by the diameter of the reinforcing steel to be  
tested. The test is illustrated in Figure A.1, Figur e A.2, Figure A.3 and Figure A.4.  
The dimensions of the test beams depend on the nominal diameter of the reinforcing steel for which the  
bond is to be determined. For nominal diameters less than 16 mm, a beam specimen of type A is used and  
for nominal diam eters equal to or larger than 16 mm, a beam specimen of type B is used (see Figure A.3  
and Figure A.4).  
 
NOTE Experience of testing bars with diameters larger than 32 mm is limited. To use the test method of this annex for such la rge 
diameters, a type test ing program should be performed to evaluate the applicability of the test method.  
 
 
 
 
 KS 2712: 2017      
  
 
 
 
 
   
©KEBS 2017 — All rights reserved  23 
 
 
A.3 Samples and specimens  
If various sizes of the same technical class of reinforcing steel and the same surface configuration are to be  
tested, they may be grouped into series. All diameters within a group shall have the same configuration  
with regard to ribs. A suitable grouping is shown in Table A.1.  
 
NOTE To have the same surface configuration implies that the relationship between rib height/bar -or-decoile d product diameter and  
rib spacing/bar -or-decoiled product diameter as well as the rib inclination is the same.  
 
Table A.1 — Series of reinforcing steel diameters for testing of bond  
Denomination of the series  Range of nominal diameters,d  
mm Representative  nominal  
diameter of the series  
mm 
Small diameters  d ≤10 8 
Medium diameters  10 <d ≤20  16 
Large diameters  20 <d ≤32  32 
Very large diameters  32 <d ≤50  Each size to be tested  
 
 
Twenty -five beam tests shall be carried out for each series and type of surface geometry with the  
representative diameter of th e series. Samples shall be selected to minimize the variation in surface  
configuration within a series. If all samples are not taken from the same bar or decoiled product, then they  
should be taken from as few bars or decoiled products as possible.  
If the representative diameter of a series is not manufactured, the largest diameter produced in the series  
shall be tested.  KS 2712: 2017      
  
If reinforcing steels with the same surface geometry but with different specified yield strength are to be  
characterized, the tests shall  be carried out with the product having the highest specified yield strength.  
The surface geometry of the reinforcing steel to be used in the tests shall be described in accordance with  
BS EN 10080:2005 and measured in accordance with ISO15630 -1:2002. All the parameters  required to 
calculate the relative rib area shall be measured and recorded.  
 
A.4 Test equipment  
A.4.1 Moulds for the test beams , made of steel, cast iron or any other non -absorbent material which does 
not react with the components of the con crete. Watertightness and dimensions should be maintained after 
use. 
 
A.4.2 Steel hinges , formed from two pieces of steel in a T shape, as shown in Figure A.1 and Figure A.2, 
which interconnect the transversal interior faces of the two blocks. The width of  the hinge is the same as 
the width, b, of the beam.  
 
A.4.3 System for regulating forces , fitted to the mechanism for applying forces, which enables them to be 
increased continuously, within the limits described in A.6. 
 
A.4.4 Force application system , for applying forces perpendicular to the face of the beam specimen.  
The mechanism for applying forces shall consist of steel rotating knife -edges or roller bearings; two to 
support the beam specimen and another two for loading.  
 
A.4.5 Instruments for measurin g forces , with an accuracy of at least 1 % of the test result.  
The reading device shall give an indication of the maximum force reached during the test.  
 
A.4.6 Instruments for measuring slip , accurate to ±0.01 mm.  
 
A.5 Preparation of samples  
A.5.1 Reinforc ing steel to be tested  
The test bar shall be in the ―as manufactured‖ condition without loose millscale, preferably entirely free  from 
rust and, if necessary, carefully degreased with carbon tetrachloride (CCl4) or ethylene trichloride  
(C2HCl3). The test b ar shall be without any machining. If the test bar is corroded, the conditions of the bar  
shall be described in the test report and possibly supported by photographs of the surface.  
The bar shall not be cleaned in any way that might change its roughness.  
Test pieces taken from coil shall be straightened according to ISO15630 -1:2002, Clause 4, prior to testing.  
 
A.5.2 Auxiliary reinforcement  
Auxiliary reinforcement should have the same strength and surface characteristics as the reinforcing steel 
to be teste d. Figure A.5 and Figure A.6 detail the components for the auxiliary reinforcement.  
 
A.5.3 Plastic sleeves  
Sleeves used to avoid the adherence of the concrete to the reinforcing steel to be tested shall be of plastic.  
These sleeves shall be rigid so as not  to become deformed during the test.  
 
A.5.4 Concrete  
A.5.4.1 General  
The concrete for the beam specimen as well as the cylindrical test pieces shall be produced, placed and 
stored according to BS EN 1766:2000 with the qualifications given in A.5.4.2 . 
 
A.5.4.2 Strength class of concrete  
The concrete shall be either of Type C  (0.70) of BS EN 1766:2000 with a compression strength target value  
of (25 ± 5) MPa, or of Type C(0,45) of BS EN 1766:2000 with a compressive strength target value of  
(50 ± 5) MPa, measur ed on 150 mm × 300 mm cylindrical specimens and tested according to  BS EN 
12390 -3.   
©KEBS 2017 — All rights reserved  25 If not otherwise agreed the tests shall be performed with concrete Type C (0, 70) of BS EN 1766:2000.  
 
NOTE It is recommended that the test pieces for 25 tests are prepared in 5 lots or mixes, making 5 specimens from each lot.  
The age of the concrete shall not be less than 21 days and not more than 35 days.  
 
 KS 2712: 2017      
 
 
 
A.6 Execution of the tests  
Resting the test beam on two rotating knife -edges or rolling bearings, load with two fo rces of equal  
magnitude, disposed symmetrically with regard to mid -span and likewise applied through movable knife  
edges  or rollers.  
The total force, Fa applied to the test piece is given by one of the following expressions:  
 
 
 
 
where  
An is the nominal cro ss-sectional area of the reinforcing steel.  
Apply loading in one of three ways:  
a) in consecutive increments corresponding to stresses, σs in the reinforcing steel of 0 MPa, 80 MPa,  
160 MPa, 240 MPa, etc.;  
b) in smaller increments; or  
c) continuously, by logging with electronic devices.  
 
 
 
For a) or b), increase the force, at each stage, gradually and continuously. Reach each increment in half a  
minute and maintain the load long enough to stabilize the slip, or, at the most, for two minutes. For c), use  
a loading speed not exceeding a corresponding stressing rate of 1 MPa/s in the reinforcing steel.  
Measure the slip at the beginning and at the end of each increment in loading.  
 
Continue the test until complete bond failure of the reinforcing steel occurs in both half -beams or until the  
reinforcing steel itself fails. Bond failure generally does not take place simultaneously in the two halfbe ams.    
©KEBS 2017 — All rights reserved  27 For this reason, when the half of the reinforcing steel whose bond has failed attains a slip of 3 mm,  hold 
this half -bar in a gripping device which will bear against the concrete and prevent any further slip.  
Force -slip curves may be either recorded a utomatically, or plotted point by point from dial gauge readings.  
 
A.7 Test results  
A.7.1 Calculation of the bond stress  
If the total force applied to the beam test is Fa, for a given slip, the bond stress, Ùb, is given by:  
 
 
 
A.7.2 Values of bond stress  
Calculate the bond stress for four measured slip values:  
 
Other values may be agreed between the parties.  
To obtain the four values of slip, record force -slip curves. These shall be made available on request.  
 
A.8 Test report  
The laboratory shall issue a report which shall contain the following information:  
a) identification of the laboratory;  
b) identification of the manufacturer of the product tested;  
c) product number;  
d) technical class of the reinforcing steel with reference  to the product specification;  
e) number of this standard (i.e. BS 4449:2005) and type of test method;  
f) nominal diameters tested and the series they represent;  
g) surface geometry of the specimen, i.e. rib/indentation heights, rib/indentation spacing, ri b/indentation  
inclinations and relative rib/indentation area;  
h) strength class of the concrete, i.e. Type C(0 .70) or Type C(0 .45) according to BS EN 1766:2000;  
i) compressive strength of the concrete at the date of testing;  
j) dates of the tests;  
k) all s ingle test results;  
l) description of the failure mode;  
m) force -slip curves.  
 
 
 
 
 
 
 
 
 
KS 2712: 2017      
 Annex B (normative)  
Material not covered by a third party product certification scheme  
 
B.1 General  
Material not covered by a third party product certification scheme sh all be assessed by acceptance tests on  
each batch. Sampling and testing shall be carried out by an independent organization at the producer’s  
works or in the stockholder’s yard.  
 
B.2 Extent of sampling and testing  
For testing purposes, the batch shall be d ivided into test units with a maximum mass of 100 t. Each test  
unit shall comprise products of the same steel grade and nominal diameter from the same cast. The  
manufacturer shall certify that all products in the test unit originate from the same cast.  
Test specimens shall be taken from each test unit as follows:  
a) fifteen specimens from different bars, for testing in accordance with B.3a) and B.3b); 
b) two test specimens, from different bars, for testing in accordance with B.3c). 
Preparation of the test s pecimens shall be carried out as described in 7.2.2 . 
 
B.3 Properties to be tested  
Specimens selected in accordance with B.2 shall be tested for the following.  
a) Inspection by variables:  
1) yield strength Re; 
2) tensile/yield ratio Rm/Re; 
3) total elongati on at maximum force Agt. 
b) Inspection by attributes:  
1) behaviour in the rebend test;  
2) deviations from the nominal mass per metre;  
3) bond strength and surface geometry.  
c) Chemical composition according to the product analysis . 
All elements listed in 7.1 and the carbon equivalent shall be determined.  
d) Fatigue properties:  
 
The fatigue properties of reinforcing steels shall be determined for each size and defined bar shape in the 
batch. Sampling and testing shall be carried out in accordance with 7.2.4 . 
The test procedure shall be as described in Clause 9. 
 
B.4 Evaluation of results  
 
B.4.1 Inspection by variables  
Inspection by variables shall be carried out as follows:  
a) The following shall be determined for the performance characteristics listed in B.3a): 
1) all individual values for each of the performance characteristics;  
2) the mean value m15 of each of the performance characteristics; and  
3) the standard deviation S15 for each performance characteristic.  
The test unit shall be deemed to conform to t his Kenya  Standard if the following conditions are met:  
m15 – 2.33 × S15 W cv for Re, and  
m15 – 1.87 × S15 W cv for Rm/Re and Agt. 
b) If the conditions in a) are not fulfilled, a secondary calculation (the acceptibility index k) shall be  
determined, where:  
If k W 2 for Re, and k W 1.6 for Rm/Re and Agt, testing shall continue. Forty -five further test specimens  
shall be taken and tested from different bars in the test unit, so that a total of 60 test results are available  
(n = 60).  
The test unit shall be dee med to conform to this Kenya  Standard if the following conditions are fulfilled:  
m60 – 1.93 × S60 W cv for Re, and  
m60 – 1.53 × S60 W cv for Rm/Re and Agt.   
©KEBS 2017 — All rights reserved  29  
B.4.2 Inspection by attributes  
Inspection by attributes shall be carried out as follows. When testing  the properties listed in B.3b), either:  
a) all the results determined on the 15 test specimens shall conform to this standard; or  
b) if a maximum of two of the 15 results do not conform to this Kenya  Standard, 45 further test  
specimens shall be taken and tested from different bars in the test unit, making 60 test results available; 
the unit shall be deemed to conform to this Kenya  Standard if no more than two of the 60 test specimens 
fail the tests.  
 
B.4.3 Fatigue properties  
The batch shall be deemed to co nform to this Kenya  Standard if it conforms to 7.2.4 . 
 
B.5 Test report  
A test report shall be produced containing the following data:  
a) the place of manufacture of the reinforcing steels;  
b) the nominal diameter of the steel;  
c) the grade of the steel;  
d) the marking on the steel;  
e) the cast number;  
f) the date of testing;  
g) the mass of the test unit; and  
h) the individual test results for all the properties specified in B.3. 
 
 
 
 
Annex C (normative)  
Identification requirements  
C.1 Bar — Identification of  the manufacturer  
C.1.1 Each reinforcing steel shall bear on one rib row, a mark identifying the works. This mark shall be  
repeated at an interval of not more than 1.5 m.  
 
C.1.2 The mark shall consist of the following:  
a) Name of manufacturer or unique identi fication of the manufacturer  
b) Grade   
c) size 
 
C.1.3 The numerical syste m identifying the manufacturer and a  works number shall use one of the 
following methods:  
a) a number of normal ribs between widened ribs (for example, see Figure C.1);  
b) a number of normal ribs between missing ribs;  
c) numbers on the surface of the bar;  
d) rolled or indented marks with a number of normal ribs in between them.  
 KS 2712: 2017      
 
 
 
C.1.4 The symbol indicating the start of the mark shall be one of the following.  
a) Where t he marking method uses widened ribs, the symbol identifying the start of the mark shall  consist 
of two consecutive widened ribs (for example see Figure C.1).  
b) Where the marking method uses missing ribs, the symbol identifying the start of the mark shall  consist of 
two consecutive missing ribs.  
c) Where numbers are rolled onto the surface of the bar, the symbol indicating the start of the mark shall  be 
an X or O.  
d) Where marks are rolled or indented onto the surface, the start of the mark shall consist of  a clearly  
identifiable starting symbol or two marks between one pair of normal ribs.  
 
C.1.5 The works number shall consist of a one or two digit number between 1 and 99, except for multiples  
of 10 (for example, see Figure C.1).  
 
C.2 Coil  
C.2.1 Coil shall be identified in the same manner as described in C.1 for bar. 
C.2.2 For coil, the manufacturer’s identification refers to the works applying the final mechanical  
properties to the coil product.  
 
C.3 Decoiled product  
C.3.1 In addition to the manufacturer’s identification placed onto the product, an identification mark of the  
decoiler shall be either made on the product or printed on an attached label.