A Comparative Assessment of the Bend, Chemical and Tensile Properties of Reinforcing Steel Bars in the Nigerian Construction Industry

A Comparative Assessment of the Bend, Chemical and Tensile Properties of Reinforcing Steel Bars in the Nigerian Construction Industry

By

JIBRIN, + M. U. and EJEH, ++ S. P.

mjibrin2002@yahoo.com and engrdrejeh@yahoo.com

+ Dr. Mohammed U. Jibrin is a Director at the National Board for Technology Incubation,

(Federal Ministry of Science and Technology), Abuja Nigeria and holds a Ph.D from the Department of Civil Engineering, Ahmadu Bello University , Zaria – Nigeria.

++ Professor Stephen Pinder Ejeh is a Professor of Civil Engineering, from Ahmadu Bello University, Zaria Nigeria.

Bend, chemical concentration/ percentage composition and tensile tests were conducted to ascertain the properties of reinforcing steel in the Nigerian Construction Industry in relation to their conformity with the BS4449 : 1997 standards. A total of fourteen (14) companies supplied nineteen(19) samples with each sample containing ten(10) specimens making a total of four hundred and eighteen(418) specimens that were used to record one thousand five hundred and twenty (1,520) data on bend, chemical concentration, percentage composition, yield, ultimate : tensile to yield strength ratio, and percentage elongation tests conducted. It was found that a sample out of the nineteen (19) tested out rightly failed the bend test despite two other samples from the same company passed. It was also noted that the tested reinforcing steel bars have significant deviation in terms of chemical composition, as most of the tested samples seem to contain a lot of impurities as evidenced by the uncontrolled presence of sulphur, phosphorus and nitrogen. Although the Carbon equivalent (C.eqv.) values are within acceptable range, there is a conspicuous absence of some critical elements such as Vanadium and molybdenum that are supposed to be important determinants of strength and ductility in many of the samples and this must have contributed to the low strength performances of the local reinforcing steel bars. Similarly, most of the samples examined did not meet the requirements of BS4449:1997 in respect of Characteristic Strength, Ductility, Tensile / yield ratio, bend, chemical percentage composition or a combination of the parameters. For example, the thirteen local reinforcing bars recorded low values of characteristic strength with a minimum of 317N/mm2 and a maximum of 410N/mm2 , with most values in between them falling within the lower quartile. While the six foreign bar performed well in characteristic strength, their corresponding elongation values of 1.67 and 2.67 are considered not only very low, but dangerous for structural applications as they can fail without warning.

Key Words: Bend, Concentration, Percentage Composition, Yield, Elongation, C.eqv.

The reinforcing steel plays a key role as a construction material whose properties should be known to the users before being used for design or construction purposes.

According to The UK Certification Authority for Reinforcing Steels (UK CARES Part 1) satisfactory reinforcing steel must be able to be bent and placed in shape with precision to fit structural elements in all aspects.

Steel reinforcing bars available in the Nigerias Construction Industry are obtained from both internal and external sources. The former comes mainly from the major steel plants in Nigeria, while imported steel bars are mainly from Russia and Ukraine. Others are those imported for specific uses by multinational companies. Most construction companies in Nigeria obtain all their reinforcing steel procurements from the open markets without any technical information that guide users on the appropriate use.

Arum, C. (2008) tensile tested some few local & foreign bars with O 10, 12, 16, 20 & 25 bars comprising Local bars were taken from Lagos, Ibadan , Akure & Ife to represent Nigeria. Buliaminu, K(2009) conducted some tensile and chemical analyses on some selected few bars. Charles, K .K. & Mark, A. (2002), tested steel in Ghana produced from metal scraps and knocked engine parts. Inuwa , I.K.(2011) under took a study of the operations of Ajaokuta Steel Rolling Company. Sanmbo, B., David, E.,Samson,A., Olatunde,S.(2009) varied production conditions of steel in the Nigerias Steel Industry and also worked on the challenges of producing quality reinforcement in West Africa. Shumatcher , K & Sathaye, J. (1998) examined production methods such as Blast Furnace , Direct.Reduction, Mini Mills methods as well as COREX being the latest tech. Various codes such as European Pr EN 10080 (E) , Russian Scientific Research Institute of Steel, Chinese std (GB/T 17107 : 1997) , ASTM A 30, BS 4449 , etc, also researched on the steel properties but not in an integrated manner.

Thus, experiments such as bend tests, chemical concentration, percentage composition tests, tensile tests, characteristic strength and ductility were carried out. The results of the comparisons show that most of the samples failed in at least one of the tests conducted.

2. All the fourteen companies from where the samples were collected were labeled in an alphabetical order as A, B, C, N. The order of identification does not mean A is better than B , as the designations are only for identification purposes. For example: A12T1 and A10T2 imply company A 12 mm diameter sample one for tension test and company A 10 mm diameter sample two for tension test respectively. Similarly A12B1 and A10B2 imply company A 12 mm diameter sample 1 for bend test and company A 10 mm sample 2 for bend test respectively.

   A12C1 and A10C2 imply company A 12 mm diameter samples 1 for chemical concentration and company A 10 mm for sample 2 chemical concentration respectively. While A12P1 and A10P2 refer to company A 12 mm diameter millimeters diameter sample 1 for percentage composition and company A 10 mm diameter sample 2 for percentage composition respectively. B12T1 and B10T2 imply company B twelve millimeter diameter sample onefor tension test and company B ten millimeter diameter sample 2 for tension test respectively, and so on.

3. 1. Ten samples were tested for each diameter with each sample consisting of a length of 500 millimeters. Each sample was bent around a former in accordance with the BS4449:1997 provisions. The test results are shown in table 1 and also plate 1 below:

      No Cracks

      S/No.	IDENTIFICATION NO.	BAR SIZE (mm)	FORMER DIAMETER	OBSERVATIONS AFTER TEST
      01	A12B	12.0	39.0	No Cracks
      02	A10B	10.0	33.0	No Cracks
      03	B10B	10.0	33.0	No Cracks
      04	B8B	8.0	27.0	No Cracks
      05	C16B	16.0	51.0	Total Breakage
      06	C10B	10.0	33.0	No Cracks
      07	C8B	8.0	27.0	No Cracks
      08	D8B	8.0	27.0	No Cracks
      09	E25B	25.0	78.0	No Cracks
      10	E20B	20.0	63.0
      11	F12B	12.0	39.0	No Cracks
      12	G12B	12.0	39.0	No Cracks
      13	H16B	16.0	51.0	No Cracks
      14	I12B	12.0	39.0	No Cracks
      15	J8B	8.0	27.0	No Cracks
      16	K10B	10.0	33.0	No Cracks
      17	L12B	12.0	39.0	No Cracks
      18	M10B	10.0	33.0	No Cracks
      19	N16B	16.0	51.0	No Cracks

      Plate I: Some Test Specimens after The Bend Tests.

   2. Ten samples were tested for each diameter. Each sample consists of a length of 500 millimeters, with sample diameter measured and then subjected to tension in accordance with the BS4449:1997 provisions. The test results are shown in table 2 and also plate II below:

      S/No	Mark	Characteristic Strength(N/mm2)	Percentage Elongation	Ultimate to Yield Strength Ratio
      1	A12T	350.00	16.50	1.55
      2	A10T	410.00	13.90	1.60
      3	B10T	390.00	19.60	1.46
      4	B8T	368.00	23.82	1.31
      5	C16T	482.00	8.33	1.84
      6	C10T	357.00	19.93	1.52
      7	C8T	387.00	21.17	1.35
      8	D8T*	463.00	1.67	1.39
      9	E25T	363.00	19.83	1.64
      10	E20T	317.00	24.27	1.43
      11	F12T	334.00	19.07	1.52
      12	G12T	408.00	14.83	1.69
      13	H16T	493.00	14.53	1.22
      14	I12T	369.00	14.50	1.69
      15	J8T*	573.00	2.67	1.21
      16	K10T*	549.00	10.07	1.22
      17	L12T*	500.00	14.93	1.21
      18	M10T*	547.00	11.77	1.08
      19	N16T*	545.00	13.90	1.26

      Plate II: Some Broken Test Specimens after Tensile Tests

Under the Chemical tests, two types of experiments were performed (a) Chemical concentration and (b) percentage composition. The actual difference is that the former is the concentration with respect to milligrammes of the element per litre and the later refers to the percentage composition of the reinforcement by weight.

1. In the determination of the elemental concentrations in milligrams per litre of the samples, stock solutions were prepared by the NARICT personnel using analar. An analar is a compound that matches with the element to be identified and capable of digesting same to form a stock solution. For example, to identify Calcium, Calcium Chloride (CaCl2) or Calcium Carbonate (CaCO3) used serial dilutions were made from the prepared stock solution within the range 1ppm, 2ppm, 3ppm, 4ppm and 5ppm. Each of the Samples was subjected to Atomic Spectrometer Shimadzu model fuelled by acetylene/ air whose output comes as a calibration curve relating the absorbance of the element and concentration. The concentrations in mg/litre are read directly from the digitized system.

   The tests were carried out in the National Research Institute for Chemical Technology, Zaria.

   The result is as shown in tables 3a and 3b.

   Table 3a: Chemical Concentration of Sample Bars in Milligrams/ Litre For Companies A To F.

   td>

   11.8

   Elements	A12C	A10C	B10C	B8C	C16C	C10C	C8C	D8C	E25C	E20C	F12C
   Aluminium (Al)	3.9	2.16	3.06	1.45	1.51	3	1.35	1.77	11.1	7.87	7.1
   Cobalt (Co)	1.55	2.23	2.03	0.7	1.99	0.32	0.48	1.88	2.44	2.27	0.9
   Copper (Cu)	7.1	7.26	8.74	2.74	7.89	1.38	1.54	9.59	8.85	8.98	2.09
   Chromium (Cr)	3	3.05	4.26	0.88	2.39	0.84	0.71	1.36	2.82	2.98	1.23
   Manganese (Mn)	6.05	5.9	5.96	6.09	6.03	6.08	6	6	5.91	6.07	5.85
   Iron (Fe)	40.7	32.4	22	33.3	20.7	23.3	25	19	23.5	31.9	31.8
   Lead (Pb)	0.98	0.46	0.27	0.18	0.64	0.95	0.3	0.49	0.24	0.33	0.22
   Nickel (Ni)	2.36	2.45	2.83	0.97	2.55	0.5	0.61	2.95	2.57	2.88	1.09
   Nitrogen(N)	0.14	0.7	0.4	0.1	2.8	4.2	4	0.31	0.08	0.7	0.8
   Zinc (Zn)	1.05	0.66	0.13	0.06	1.05	0.1	0.09	0.26	0.52	0.77	0.37
   Phosphate (Po3)	5.3	13.6	3	3	7.3	1.6	13	3.5	8	0.6
   Sulphide (S)	0.24	2.34	2.5	0.5	0.02	0.1	0.45	1.5	2.01	0.02	0.2

   Table 3b: Chemical Concentration of Sample Bars in Milligrams/Litre For Companies G To N.

   Elements	G12C	H16C	I12C	J8C	K10C	L12C	M10C	N16C
   Aluminium (Al)	1.19	3.55	2.42	1.1	3.68	4.77	2.23	5.26
   Cobalt (Co)	1.94	2.25	3.32	2.11	1.49	2.24	1.57	2.38
   Copper (Cu)	6.64	9.14	9.59	10.9	9.32	9.98	9.07
   Chromium (Cr)	1.96	2.98	4.65	2.24	2.66	1.55	2.07	3.21
   Manganese (Mn)	6	6.08	6.01	6.04	6.06	5.94	5.88	6.01
   Iron (Fe)	26.9	29.9	20.7	15.8	34.1	26.3	31.3	32
   Lead (Pb)	0.92	0.22	0.64	0.42	0.49	0.67	0.48	0.55
   Nickel (Ni)	2.3	3.83	3.82	2.8	3.26	3.05	3.83
   Nitrogen(N)	2.4	3.1	0.05	0.95	0.02	0.3	0.01	2.05
   Zinc (Zn)	0.7	0.37	1	0.52	0.51	0.4	0.31	0.34
   Phosphate (Po3)	0.4	39	0.3	3.4	47.7	4.8	20.3	2.1
   Sulphide (S)	0.21	0.06	0.15	0.04	3.2	0.03	0.05	0.01

The Chemical Composition of the samples were carried out using the XRF spectrometer at the Centre for Energy Research and Training , at Ahmadu Bello University, Zaria and the results are as shown in the tables 4a and 4b below:

2. From table 1 below, one can clearly observe that the assumed market diameters for all the reinforcing steel bars are less than the measured diameters for all the bars considered. A very large discrepancy was also observed on sample J8T which is designated and sold in the market as 8 mm bar against its measured diameter of 6.5mm.

   S/No	Mark	Market Designated Diameter (mm)	Measured Diameter (mm)	Percentage Difference
   01	A12T	12.00	11.88	1.00
   02	A10T	10.00	9.65	3.50
   03	B10T	10.00	9.56	4.40
   04	B8T	8.00	7.44	7.00
   05	C16T	16.00	15.82	1.13
   06	C10T	10.00	9.55	4.50
   07	C8T	8.00	7.46	6.75
   08	D8T	8.00	7.23	9.63
   09	E25T	25.00	24.56	1.76
   10	E20T	20.00	19.57	2.15
   11	F12T	12.00	11.40	5.00
   12	G12T	12.00	11.48	4.33
   13	H16T	16.00	15.52	3.00
   14	I12T	12.00	11.40	5.00
   15	J8T	8.00	6.50	18.75
   16	K10T	10.00	9.36	6.40
   17	L12T	12.00	11.82	1.50
   18	M10T	10.00	9.23	7.70
   19	N16T	16.00	15.60	2.25

   Where the diameter cannot be approximated to the assumed market diameter, then there is a problem. For example, sample B8T 7.44mm cannot be approximated to 8mm, D8T cannot approximate to 8mm, F12T, 11.40 cannot be 12.0mm, I12T and K16T. These were the problems observed.

3. In line with BS4449: 1997 requirements which specify ± 6.0 % for 8mm and 10 mm bars and ± 4.5% for 12mm bars and above, it can be seen from table 6 that the percentage tolerances for most of the reinforcement bars irrespective of origin fall out of range. Thirteen bars are out of range, while only six fall within the acceptable range.

   S/N	Mark	Measured Cross- Sectional Area (mm2)	Effective Cross- Sectional Area (mm2)	Tolerance Differences (%)	BS4449/1997 Min. Tolerance (%)	Remarks
   1	A12T	110.79	86.14	+22.25	± 4.5	Out of Range
   2	A10T	73.10	71.96	+1.56	± 6.5	Within Range
   3	B10T	71.74	70.98	+1.06	± 6.5	Within Range
   4	B8T	43.45	48.37	-11.32	± 6.5	Out of Range
   5	C16T	196.46	160.14	+18.49	± 4.5	Out of Range
   6	C10T	71.59	72.42	-1.16	± 6.5	Within Range
   7	C8T	43.69	49.85	-14.10	± 6.5	Out of Range
   8	D8T*	41.03	36.27	+11.60	± 6.5	Out of Range
   9	E25T	473.51	316.93	+33.07	± 4.5	Out of Range
   10	E20T	300.64	281.13	+6.49	± 4.5	Out of Range
   11	F12T	102.02	88.84	+12.92	± 4.5	Out of Range
   12	G8T	103.46	85.17	+17.68	± 6.5	Out of Range
   13	H12T	189.08	95.77	+49.35	± 4.5	Out of Range
   14	I16T	100.24	87.47	+12.74	± 4.5	Out of Range
   15	J12T*	33.17	34.74	-4.73	± 6.5	Within Range
   16	K10T*	68.77	70.12	-1.96	± 6.5	Within Range
   17	L12T*	109.07	110.30	-1.13	± 6.5	Within Range
   18	M10T*	66.88	71.77	-7.31	± 4.5	Out of Range
   19	N16T*	191.04	211.28	-10.60	± 6.5	Out of Range

   * Implies foreign bars

   This indicates that the thirteen bars that are out of range have varying diameter along the length which is not the best for reinforcing bars. This should be carefully checked to ensure an average close diameter throughout the length. Thus, most of the steel in the construction industry in Nigeria have varying diameters along the length.

Eighteen out of the nineteen samples have passed the bend test as neither micro cracks , nor any form of unacceptable deformation were observed. It is worthy to note that C16B , C10B and C8B are from the same company.

If such reinforcement like C16B, which is company C with bar diameter 16 millimetres are used in structural elements, the element may fail without warning. On observing the bar carefully, the ultimate to yield strength ratio is 1.84, characteristic strength is 482N/mm2 , the cross sectional area percentage tolerance is +18.49 which is out of range. The elongation is 8.3 percent which is far below the 14 percent. The company has to check the production line carefully. This situation indicates high content of carbon with no elements for ductility. There is a need to reduce high carbon content.

1. The characteristic strengths computed from the yield strengths are shown in table 8 and are compared with the code requirements.

   S/No	Mark	Characteristic Strength(N/mm2)	Min. BS4449/1997 Provisions	Remarks
   1	A12T	350.00	460.00	Below => Unsatisfactory
   2	A10T	410.00	460.00	Below => Unsatisfactory
   3	B10T	390.00	460.00	Below => Unsatisfactory
   4	B8T	368.00	460.00	Below => Unsatisfactory
   5	C16T	482.00	460.00	Above => Satisfactory
   6	C10T	357.00	460.00	Below => Unsatisfactory
   7	C8T	387.00	460.00	Below => Unsatisfactory
   8	D8T*	463.00	460.00	Above => Satisfactory
   9	E25T	363.00	460.00	Below => Unsatisfactory
   10	E20T	317.00	460.00	Below => Unsatisfactory
   11	F12T	334.00	460.00	Below => Unsatisfactory
   12	G12T	408.00	460.00	Below => Unsatisfactory
   13	H16T	493.00	460.00	Above => Satisfactory
   14	I12T	369.00	460.00	Below => Unsatisfactory
   15	J8T*	573.00	460.00	Above => Satisfactory
   16	K10T*	549.00	460.00	Above => Satisfactory
   17	L12T*	500.00	460.00	Above => Satisfactory
   18	M10T*	547.00	460.00	Above => Satisfactory
   19	N16T*	545.00	460.00	Above => Satisfactory

   * Implies foreign bars

   Observing carefully, eleven out of nineteen samples fall below the characteristic strength. This is not good enough.

2. Table 8 below shows the ratio of the ultimate to yield strength. It can be seen that the ultimate to yield strength ratio values in respect of all the nineteen samples are above the minimum code provisions. The values obtained for the fourteen local samples are relatively higher than those obtained for the foreign bar samples, which are very close to the minimum.

   S/No	Mark	U : Y Ratio	BS4449/ 1997 Provisions Minimum .	Remarks
   1	A12T	1.55	1.15	Above => Satisfactory
   2	A10T	1.60	1.15	Above => Satisfactory
   3	B10T	1.46	1.15	Above => Satisfactory
   4	B8T	1.31	1.15	Above => Satisfactory
   5	C16T	1.84	1.15	Above => Satisfactory
   6	C10T	1.52	1.15	Above => Satisfactory
   7	C8T	1.35	1.15	Above => Satisfactory
   8	D8T*	1.39	1.15	Above => Satisfactory
   9	E25T	1.64	1.15	Above => Satisfactory
   10	E20T	1.43	1.15	Above => Satisfactory
   11	F12T	1.52	1.15	Above => Satisfactory
   12	G12T	1.69	1.15	Above => Satisfactory
   13	H16T	1.22	1.15	Above => Satisfactory
   14	I12T	1.69	1.15	Above => Satisfactory
   15	J8T*	1.21	1.15	Above => Satisfactory
   16	K10T*	1.22	1.15	Above => Satisfactory
   17	L12T*	1.21	1.15	Above => Satisfactory
   18	M10T*	1.08	1.15	Below => Unsatisfactory
   19	N16T*	1.26	1.15	Above => Satisfactory

   * Implies foreign bars

   It can be observed that bars samples M10T which is a foreign sample is below minimum requirement. This could be as a result of cooling process which is a manufacturing fault within the line of production. However, when the ratio is high, it is not good either. It implies high carbon content which may lack ductility.

From the table 10 below, it can be seen that most of the local bar samples met the minimum code requirements on elongation, while most of the foreign bars did not meet the minimum codes requirements. Serial numbers 5, 8, 15, 16 and 18 failed to reach the value of 14 percent and on observing carefully sample nos. 5, 6 and 7 are of the same company, but sample no. 5 failed to satisfy the elongation requirement. Secondly, samples nos. 15 to 19 and also no. 8 are foreign companies and only the sample with serial number 17 passed.

These samples that failed in elongation should not be used in reinforcement as they will not give warning prior to failure due to low ductility.

A total of fourteen (14) elements were identified for the Chemical Concentration in Milligrams Per Litre using the analar , while twenty eight (28) elements were discovered in the Determination of Elemental Percentage Composition By Weight using the XRF spectrometer.

The highest concentration element for all the samples is Iron (Fe) , which is followed by manganese and copper.The behaviour of Manganese, Carbon, Copper and Chromium being strength and coefficient of weldability determinants across the nineteen samples was further investigated. Similarly, the behaviour of Iron being the principal steel constituent checked. It is worthy to note that these five important elements considered showed no convergence at any

point between elements from the same country of origin or company source. For example, a company that produced two or three of these samples was showing different percentage composition for each sample, implying a negative signal with the production process, quality control, personnel, equipment or their combination. These have been represented in graphs I and II respectively.

3.9 Some Measured Parameters:

The value of standard deviation will determine the skilled people that are under employment. The small the value indicates high skilled personnel were employed. Values below or equal to five are an indicative of highly skilled personnel and above five indicates employment of low skilled men which lead to bad products, etc. About five samples from company C, F, H, K and M have values above five. A balance must be maintained for effective administration and good output.

The weldability of the reinforcing steel bars can be understood from the table as relevant code and standards (BS 4449: 1997) stipulates a maximum value of 0.51 for high tensile steel given that Carbon equivalent value is usually a function of the percentages composition of C, Mn, Ni, Cu, Mo, V, and Cr. The weldability statistics of the tested steel bars are hereby presented in table 13 below.

Table 4 of BS4449 prescribes a maximum value of 0.51 for high tensile steel bars. Thus, data obtained was used to compute the carbon equivalent value using the formula:

Ceqv = C + Mn/6 + ( Cr + Mo + V )/5 + (Ni + Cu)/15 as provided by the code and confirmed by Sanmbo B., David E., Samson A., and Olatunde S., (2009).

TABLE 13: CARBON EQUIVALENT VALUE (WELDABILITY COEFFICIENT) OF STEEL BAR

From table 14 below, five tested parameters were checked with each diameter samples.

TABLE 14: BEND AND TENSILE TEST PARAMETERS.

TABLE 15a: PERCENTAGE CHEMICAL COMPOSITION PARAMETERS COMPANIES (A – F)

TABLE 15b: PERCENTAGE CHEMICAL COMPOSITION PARAMETERS COMPANIES (G – N)

Legend :=> Within Code Provision; X=> Outside Code Provision; – => No Trace of the Element

Tables 15a and 15b were prepared for only elements whose specifications were given by the code.

1. Based on the tensile test conducted and the analyses/ observations carried out the following conclusions were made.

   1. There is a variation between the actual and measured bar diameters for the nineteen samples. There is also variation of diameters along the length of each diameter bar.

   2. The characteristic strength values for most of the locally produced bar samples are low compared to the BS4449:1969,1995& 1997 standards for high tensile steel which is 460N/mm2 minimum value.

   3. The characteristic strength values in respect of the local bars suggest similarities with characteristics strength of mild steel. This implies the products are actually mild steel rolled and openly sold as high tensile steel after rethreading.

   4. Most of the reinforcement bar samples complied with the minimum ultimate to yield strength ratio as specified by BS 4449: 1969 and 1997 code provisions.

   5. The percentage elongation values for most of the locally produced bar samples are within acceptable code limits, the values for most of the foreign bar samples are below the minimum standard provisions.

   6. Despite the evidence of brittleness in the foreign bars, only one out of the three samples from company C (C16 B) failed the bend test.

   7. Elongation and bend tests are to be carried out to confirm brittleness or lack of ductility.

   8. The chemical concentration test results showed thirteen elemental constituents only, while the chemical percentage composition tests gave twenty seven.

   9. All the ten elements mentioned by the BS4449 code were identified in addition to seventeen other elements adding up to twenty seven.

   10. Most of the elements whose composition limits were not specified by any code showed presence in traces.

   11. There is an indication of the presence of impurities as evidenced by the traces of silicon, phosphorus, sulphur or their combination in most of the samples tested.

   12. Elements that add to strength and carbon equivalent value like Molybdenum, Vanadium, etc. were present in the samples.

   13. Iron being the principal component of reinforcement steel varies from seventy four percent (74.5%) to ninety eight point four percent (98.4%) in the samples.

   14. All the nineteen samples tested complied with code value on carbon equivalent values.

   15. Evidence of products technical information is absent in the open market where bulk of the products are sold to the construction industry, even for the locally produced bars.

   16. From the field survey carried out it is confirmed that only clients of corporate projects pay serious attention to materials testing at site for proper documentation.

2. On the basis of the findings of this study, the following recommendations are hereby made.

   1. Reinforcement steel users must ensure that all reinforcement to be used in any construction work must be selected / tested for all vital parameters as checked in this research in accordance with the BS4449 (1997 or 2005) provisions.

   2. All imported reinforcing steel must be checked for compliance prior to accepting it in Nigeria and such consignment must be accompanied by with an accredited certification.

The kind permission of Professor (Mrs) Gambo Laraba Abdullahi , Director General and Chief Executive Officer , National Board for Technology Incubation, Abuja Nigeria, former Honourable Minister for Women Affairs Federal Republic of Nigeria to undertake the successful conduct of the research and the useful advice during the experimentation are highly appreciated. Her effort and good administrative skills are also acknowledged.

Arum, C. (2008) : Verification of Properties of Concrete Reinforcement Bars:- Nigerian Case Study – Published by : http:ibe.sagepub.com PP.370-376

American Society for Testing of Materials: (2007) Standard Test Methods and Definitions for Mechanical Testing of Steel Products: ASTM A37-07a

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