Transactions Template JOURNAL OF ENGINEERING RESEARCH AND TECHNOLOGY, VOLUME 5, ISSUE 1, DECEMBER 2018 13 Applying Reused Steel Bars to New Constructions (A Case Study in Gaza Strip) Bassam A. Tayeh 1,a* Mohammed W. Hasaniyah 1,b Mohammed Ziad Abu Anza 1,c Mohammed A. Abed 2,d 1 Civil Engineering Department, Faculty of Engineering, Islamic University of Gaza, Gaza, Palestine 2 Budapest University of Technology and Economics, Müegyetem rkp. 3, Budapest 1111, Hungary a btayeh@iugaza.edu.ps b mhasaniyah@gmail.com c mohemm34@gmail.com d mohammed.a.m.abed@hotmail.com *Corresponding author: Bassam A. Tayeh , Civil Engineering Department, Islamic University of Gaza, Gaza, Pales- tine, Tel: + 972-82644400; Fax: + 972-82644800 , E-mail: btayeh@iugaza.edu.ps Abstract—Demands for construction materials and for steel in particular are globally increasing. In 2008, the construction sector consumed 56% of the total 1088 million tons of steel demand. Steel production is a major contributor to greenhouse emissions with an estimated 25% of total CO2 emissions. Therefore, reusing and recycling steel could be beneficial in lowering the global levels of CO2 emissions. This paper examines the possibility of using steel form the debris of damaged buildings during the 2014 war on Gaza, Palestine. The lack of steel bars and their uprising prices in Gaza strip encouraged the trend of using used steel in new constructions. The paper examines the properties of used steel in comparison with the standards. It also compares between steel of known and unknown extraction sources and between steel extracted under an expert supervision and steel extracted by local residents. The validity of reused steel is examined through a process of Re-certification. The process includes applying a tensile and bend and re-bend test to used steel bars. The results indicate that some reused steel bars meet the specification for new constructions. The results also show that steel bars extracted under a specialist supervision shows better performance than those extracted by local steel collectors in Gaza. Index Terms: CO2 emissions, Bend & Re-bend test, Destroyed buildings, Gaza Strip, Reused steel bars, Tensile test. I INTRODUCTION Steel is the most widely used engineering material around the world; the global demands for steel in 2008 was estimat- ed at 1088 million tons. The construction sector consumed approximately 56% of global steel demands. These were divided into 358 million tons in buildings and 238 million tons in infrastructure projects [1]. Steel production is one of the major causes for greenhouse gas emissions. The global industrial carbon emissions are around 10000 million tons CO2; steel industry approximately produces 25% of these emissions [2]. Therefore, research attempts for recycling or reusing steel might have beneficial effects on reducing CO2 emissions. In a research carried in the Netherlands, the Unit- ed Kingdom, and Sweden, it was found that at the end of a facility life, 83% of steel are recycled, 14% are reused and 3% are landfilled [3]. Although several steel sections are reused, steel bars from reinforced concrete buildings are never reused globally [4]. It was also found that reusing a particular amount of steel for one time can reduce CO2 emis- sions by 35% in comparison of using newly-fabricated-steel members. Recycling these used members for one more time can decrease CO2 emissions by 45% in comparison with using new members. These numbers reflect the importance of recycling and reusing steel instead of fabricating new steel members. They also show that there is a barrier for steel reusing and that industry prefers steel recycling [5, 6]. Reusing steel members offers greater environmental ad- vantages than recycling since there is no (or few) environ- mental impacts associated with reprocessing. For example, https://www.facebook.com/Mohammed.W.Hasaniyah?hc_ref=ART4VGBPq4wg_wtDxrfN40oX7Nh-h9hYx4CBo05PM5s73MPGrTXLS5fOyoMJVjjy-iY&fref=nf mailto:btayeh@iugaza.edu.ps mailto:mhasaniyah@gmail.com mailto:c%20%20mohemm34@gmail.com mailto:mohammed.a.m.abed@hotmail.com mailto:btayeh@iugaza.edu.ps mailto:cemamj@eng.usm.my,%20mgtazmi@yahoo.com Bassam A. Tayeh, Mohammed W. Hasaniyah, Mohammed Ziad Abu Anza and Mohammed A. Abed / Applying Reused Steel Bars to New Constructions (A Case Study in Gaza Strip) (2018) 14 reusing a steel beam in its existing form is more efficient energy and cost wise than re-melting the beam and fabricat- ing a new member out of it. Over 500 million tons of steel are recovered and recycled annually worldwide. The United Kingdom construction in- dustry consumes around 420 million tons of materials annu- ally and generates some 90 million tons of construction, demolition and excavation waste, of which 25 million tons end up in landfills [7]. The economic value of reusing steel can be strongly linked to the cost of new steel [8]. Reusing steel is advantageous in construction from both economic and environmental per- spectives. However, there are some barriers that limit the applications of reused steel in new constructions. These bar- riers are summarized in the following points: 1. Sourcing Steel: Reusing steel members in new constructions requires that the extracted members from old constructions meet the design require- ments of the new construction. This requires the design team to investigate the reuse supply early in the design process to attempt to secure appropriate sections [6]. There is usually a limited supply of re- used steel that fits the new design, which results in a mixture of reused and new steel. Sourcing steel requires an intensive work from the structural de- sign team leading to an increase construction cost. The sourcing process generally requires a longer project preparation program to ensure the steel is sourced, tested, re-fabricated (where required) and delivered to site ready for construction. Sourcing of steel can be a challenge since construction is usual- ly faster than demolition which limits the supply of reused steel [6, 9]. 2. Cost implications for structural steel reuse: There are no inclusive data about the costs of reus- ing steel due to inexperience of reusing steel worldwide. However, it must contain the costs of deconstruction, shot-blasting, labor work, Recondi- tion/Certification and fabrication with reclaimed steel. Additional costs of reused steel could emerge from delays in the construction process. These de- lays could be prevented if using reused steel is planned for at an early stage [2, 6, 10]. 3. Steel Re-certification: If steel is to be reused, a specialist must take responsibility for certifying its suitability. A visual inspection is firstly required to identify distortion, deflection and significant corro- sion segments of the member to be reused. If the steel grade is unknown, either the lowest grade could be assumed, and the structure is designed ac- cordingly, or a tensile test can be conducted to de- termine the steel grade [4, 6]. 4. Lack of client demand or negative client percep- tions: Clients of new constructions prefer new steel members over reused steel. This results in a lower demand rates for reused steel [2, 10]. CASE STUDY Gaza strip is one of the most crowded areas in the world, where about 2 million inhabitants live in approximately 365 km 2 [11, 12]. During the past decade, the strip suffered the consequences of consecutive wars which destroyed plenty of buildings and infrastructure either wholly or partially. The prices of steel in Gaza have increased as a result of continu- ously increasing demand and limited supply. The amount of construction waste from the destroyed houses after the war of 2014 is estimated at about 2.5-3.0 million tons; 22% of this amount is made of steel bars [4, 13, 14] (Fig. 1). The 2008 war left approximately 1 million tons of construction wastes [12]. The strip requires huge amounts of construction materi- als for buildings rehabilitation and natural growth require- ments. In October, 2016, Gaza strip requirements for con- struction materials were estimated at about 31 million tons [15]. According to the United Nations Office for Projects Services (UNOPS), the allocated quantities of construction materials on their system, Gaza Reconstruction Mechanism (GRM), Bassam A. Tayeh, Mohammed W. Hasaniyah, Mohammed Ziad Abu Anza and Mohammed A. Abed / Applying Reused Steel Bars to New Constructions (A Case Study in Gaza Strip) (2018) 15 are 1,046,005 tons cement, 3,904,891 tones aggregates, and 185,161 tons steel bars with a total of 5,136,057 tons [15]. The demand for steel bars in 2014 was 1,049,079.75 tons. However, only 113,702 tons of steel bars were allowed into Gaza Strip between 2014 and 2016. This has left a deficit of 935,377.75 tons in steel supply [15]. This study attempts to validate the reuse of steel bars from destroyed constructions in new buildings. This approach Fig.1 Steel bars collection might help in lowering the strip needs for new steel bars. The sources of reused steel bars are destroyed buildings due to bombing or demolishing. This paper examines the possibility of using steel form the debris of damaged buildings during the wars on Gaza. The paper examines the properties of used steel in comparison with the standards. It also compares between steel of known and unknown extraction sources and between steel extracted under an expert supervision and steel extracted by local resi- dents. II METHODOLOGY This study aims to confirm the performance and quality as- surance requirements for reused steel bars [16] by examining one of the steel reusing barriers, Steel Re-certification. The grade and performance of reused steel are determined and compared with the standards of new steel bars. Thereby, the behavior and suitability of reused steel bars can be deter- mined. The samples of steel bars are collected and categorized ac- cording to their extraction source and whether the bars were sampled under a specialist supervision or not. 27 steel bar samples of various diameters are collected. The three differ- ent categories of samples are illustrated in table (1). Table 1: Categories of steel bar samples according to extraction source and the availability of a specialist Sample No. Extraction Source Specialist Supervision During Extraction Notes 1 Unknown extraction place No The samples are collected from local shops in Gaza that sells reused steel. 2 Known extraction place No - 3 Known extraction place Yes - The samples of known extraction sources are compared with those of unknown extraction sources. The samples extracted under the supervision of a construction engineer are com- pared with those extracted by local residents. This metho dology is followed to check whether the extraction place and the specialist supervision affect the performance and quality of reused steel or not. Steel Re-certification is applied to all samples by firstly vis- Bassam A. Tayeh, Mohammed W. Hasaniyah, Mohammed Ziad Abu Anza and Mohammed A. Abed / Applying Reused Steel Bars to New Constructions (A Case Study in Gaza Strip) (2018) 16 ually inspecting steel bars to determine if there any distor- tions, deflections or significant corrosions in the steel bar. Then, to determine the performance of steel bars, two tests are conducted: 1. Steel Tensile Test: This test is conducted to deter- mine the steel grade. The tensile test is performed according to (ASTM A370) standard to determine the yield stress (N/mm 2 ), the ultimate stress (N/mm 2 ), the elongation percentage, and the Fu/Fy ratio for each steel bar [17] (Fig. 2). Fig. 2 Tensile test of steel bars 2. Bend and Re-Bend Test: This test is executed ac- cording to (ASTM A370) standard to determine if there are any cracks in the steel bars [17] (Fig. 3). Fig. 3 Bend and re-bend test The tested reused steel bars are then compared with the specifications of the (PS 52-1997) standard [18]. III RESULTS Table (2) represents the results of the tensile test for the 27 steel bar samples of unknown extraction source. The results indicate that 40.7% of all samples failed at least one limita- tion standard test (Fig. 4). Out of six Ф14 bars, five have failed to reach the minimum yield stress point. One out of four Ф18 bars has failed to reach the minimum as well. All Ф10 and two out of seven Ф16 bars have exceeded the maximum yield stress of 520 N/mm 2 . Table (2) also shows that three Ф14 bars have failed to reach the minimum ultimate strength of 500 N/mm 2 . Fig. 4 Samples after tensile test Table (3) shows the results of the tensile test for 33 steel bar samples that are collected form known sources under a spe- cialist supervision. The table reveals that 60.6% of samples have failed at least one limitation of the tensile standard test. Some steel bar samples do not have yield stress point which indicates that the bar has reached its yield limit before test- ing in the extraction site. Table (3) also shows that 18 steel bars failed to reach the minimum elongation percentage. The ground beam steel bars, which were extracted under supervi- sion, have met all the requirements of the tensile test. Bassam A. Tayeh, Mohammed W. Hasaniyah, Mohammed Ziad Abu Anza and Mohammed A. Abed / Applying Reused Steel Bars to New Constructions (A Case Study in Gaza Strip) (2018) 17 Table 2: Tensile test results of samples from unknown source (shaded cells indicate a failure of sample) Bar No. Specified Size (mm) Yield Stress (N/mm 2 ) Ultimate Stress (N/mm 2 ) Elongation % Fu/Fy Ratio 400-520 min 500 min 12 % min 1.25 1 8 478.5 657.9 20.5 1.38 2 8 478.5 657.9 21 1.38 3 8 477.5 676.5 20.5 1.42 4 10 534.7 702.2 15.7 1.31 5 10 536.7 704.2 12.5 1.31 6 10 530 670 13.5 1.26 7 12 484.9 657.1 17.6 1.36 8 12 420 530 12.5 1.26 9 12 450 567 12.6 1.26 10 14 423 584 14 1.38 11 14 419.5 542 13.2 1.29 12 14 395 658 12 1.66 13 14 311.4 543.3 16 1.74 14 14 251.8 377.7 17.5 1.5 15 14 185.5 497 17.5 2.68 16 14 231.9 463.8 17 2 17 16 463.8 589 12.9 1.27 18 16 474 730.6216 14.9 1.54 19 16 474 739.2 16.9 1.56 20 16 547.9 740.7 17 1.35 21 16 522.5 700.1 16 1.34 22 16 507.3 700.1 16.5 1.38 23 16 507.3 700.1 16.5 1.38 24 18 409.9 668.6 15.5 1.63 25 18 394.8 592.2 15 1.5 26 18 403.5 585.5 14.5 1.45 27 18 403.5 549.9 14.5 1.36 Table 3: Tensile test results of samples from known extraction source (shaded cells indicate a failure of sample) Bar No. Extraction place Specified Size (mm) Yield Stress (N/mm 2 ) Ultimate Stress (N/mm 2 ) Elongation (%) Fu/Fy Ratio Bassam A. Tayeh, Mohammed W. Hasaniyah, Mohammed Ziad Abu Anza and Mohammed A. Abed / Applying Reused Steel Bars to New Constructions (A Case Study in Gaza Strip) (2018) 18 Limits 400-520 min 500 min 12 % min 1.25 1 slab 12 505.1 721.5 10 1.43 2 slab 12 519.3 662.5 6 1.28 3 slab 12 504.9 685.3 8.5 1.36 4 slab 12 432.8 694.3 8.5 1.6 5 slab 12 289.2 385.6 9.5 1.33 6 Column 12 432.8 712.3 10.5 1.65 7 Column 12 423.8 694.3 7 1.64 8 slab 12 487 708 12.5 1.45 9 slab 12 443 700 15 1.58 10 Column 12 - 735 15 0 11 Column 12 531 717 15 1.35 12 Column 12 576 691 10 1.2 13 Column 12 461 708 10 1.53 14 slab 14 - 760 5 0 15 slab 14 - 617 2 0 16 slab 14 487 747 4 1.53 17 slab 14 - 682 5 0 18 *ground beam 14 461 721 17.5 1.56 19 *ground beam 14 461 734 15 1.59 20 *ground beam 14 516 720 16 1.35 21 *ground beam 14 520 688 14 1.32 22 *ground beam 14 515 735 15.5 1.42 23 *ground beam 14 500 704 16 1.408 24 *ground beam 14 516 705 12.5 1.36 25 Column 14 448 682 15 1.52 26 Column 14 454 689 17.5 1.51 27 Column 14 - 682 7.5 0 28 slab 16 429.9 687.8 8 1.6 29 slab 16 546.3 698 10.5 1.28 30 slab 16 489.6 636 8.5 1.3 31 Column 20 448.1 746.8 12.5 1.67 32 Column 20 438.3 766.2 12.5 1.75 33 Column 20 431.8 756.5 11.5 1.75 *Under the supervision of an expert Table 4 shows the results of the bend and re-bend test for 27 samples collected from known extraction sources. The reults indicate that all the samples have passed the test (Fig. 5). Bassam A. Tayeh, Mohammed W. Hasaniyah, Mohammed Ziad Abu Anza and Mohammed A. Abed / Applying Reused Steel Bars to New Constructions (A Case Study in Gaza Strip) (2018) 19 Table 4: The results of bend & Re-bend tests of reused steel samples. Ø (mm) Sample Extraction place Actual Ø Pass or Fail 8 1 slab 7.73 PASS 2 slab 7.57 PASS 3 slab 7.71 PASS 12 4 slab 11.92 PASS 5 slab 11.9 PASS 6 slab 11.88 PASS 7 slab 11.98 PASS 8 slab 11.89 PASS 9 slab 11.93 PASS 10 slab 12 PASS 11 Column 12 PASS 12 Slab 12 PASS 14 13 Slab 14.56 PASS 14 slab 13.67 PASS 15 slab 14.83 PASS 16 slab 13.72 PASS 17 slab 14.59 PASS 18 slab 15.32 PASS 19 slab 15.56 PASS 20 slab 16.33 PASS 21 slab 15.46 PASS 22 slab 15.38 PASS 23 slab 16.19 PASS 24 slab 15.56 PASS 25 slab 16 PASS 26 slab 16 PASS 20 27 Column 19.6 PASS Bassam A. Tayeh, Mohammed W. Hasaniyah, Mohammed Ziad Abu Anza and Mohammed A. Abed / Applying Reused Steel Bars to New Constructions (A Case Study in Gaza Strip) (2018) 20 Fig. 5 Samples after bend & re-bend test IV CONCLUSION The possibility of applying reused steel to new constructions in Gaza has been studied in this paper through the process of re-certification; a visual inspection, a tensile test and a bend and re-bend test are performed on each reused steel bar. The results were varying depending on the site and the construc- tion elements from which the steel bars were collected. The demolition process of the source building is another im- portant factor affecting the quality of the steel bar. The ex- traction of steel bars under the supervision of a specialist has clearly enhanced the performance of reused steel bars. The steel bars extracted from ground beams under a specialist supervision did not fail any of the tensile test requirements. The bars that passed all the tests could be used in new con- structions as alternatives to newly casted steel bars. In con- clusion, although steel reuse is not a common practice worldwide, it is recommended to use reused steel bars in Gaza Strip after applying all the required tests to recertify the steel bar. ACKNOWLEDGEMENT The authors are grateful to the staff of the Islamic University of Gaza (IUG) Soil and Materials Lab for their help during the sample preparation and testing. Special thanks are di- rected to senior civil engineering students Mohammed Mo- hamed Abu Mostafa, Tareq Atef Zourob Hamdan Sofian El- Astal, for helping the authors in carrying out the experi- mental program. REFERENCES 1. J. Cullen and M. Drewniok, "Structural steel reuse. Steel and the circular economy", The Building Centre, London. University of Cambridge. 30 November 2016. 2. J. Cullen, "Steel reuse in construction. Resource Effi- ciency Collective", University of Cambridge. Jun. 2016. 3. E. 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