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    Experimental investigation and analytical prediction of flexural behaviour of reinforced concrete beams with steel fibres extracted from waste tyres
    (Elsevier, 2023) Yildizel, Sadik Alper; Ozkilic, Yasin Onuralp; Bahrami, Alireza; Aksoylu, Ceyhun; Basaran, Bogachan; Hakamy, Ahmad; Arslan, Musa Hakan
    In recent years, studies on the use of car tyre wastes in concrete have gained momentum. Especially, the effect of recycled waste steel wires (RWSWs) from tyres to be mixed into concrete for using in newly designed reinforced concrete buildings on the performance of construction elements is a fairly new research area. In this study, the bending behaviour of 12 reinforced concrete beams was investigated having 1/3 geometric scale, 100 x 150 x 1000 mm in size, and produced with RWSWs additive in different volumetric ratios (1%, 2%, and 3%) under vertical loads. Another main parameter selected in the study was the amount of varying tension reinforcements (24)12, 24)10, and 24)8). The load-carrying, stiffness, ductility, and energy dissipation capacities of the RWSW reinforced bending beams were compared with the primary aim of this study which was to examine and present the contribution of RWSWs on the improvement of the bending performance of the reinforced concrete beams. The results revealed that the mechanical properties of the hybrid beams with RWSWs vary depending on dosages but are comparable with those of the beams-only with the same fibre dosage. A positive effect was obtained for the hybrid beams containing 2-3% RWSWs. Besides, RWSWs were found to be highly well mobilised at larger crack widths, and the post-cracking strength of RWSW mixes was significantly higher. Considering both mechanical properties of the beams and fresh properties such as the workability, 2% of RWSWs is recommended to be utilised in the reinforced concrete beams. On the other hand, the results were compared with the predictions of the methods given in the literature and standards. Moreover, an equation was derived to better predict the capacity of the hybrid beams using RWSWs.
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    Experimental tensile test and micro-mechanic investigation on carbon nanotube reinforced carbon fiber composite beams
    (Techno-Press, 2023) Madenci, Emrah; Ozkilic, Yasin Onuralp; Hakamy, Ahmad; Touns, Abdelouahe
    Carbon nanotubes (CNTs) have received increased interest in reinforcing research for polymer matrix composites due to their exceptional mechanical characteristics. Its high surface area/volume ratio and aspect ratio enable polymer-based composites to make the most of its features. This study focuses on the experimental tensile testing and fabrication of carbon nanotube reinforced composite (CNTRC) beams, exploring various micromechanical models. By examining the performance of these models alongside experimental results, the research aims to better understand and optimize the mechanical properties of CNTRC materials. Tensile properties of neat epoxy and 0.3%; 0.4% and 0.5% by CNT reinforced laminated single layer (0 & DEG;/90 & DEG;) carbon fiber composite beams were investigated. The composite plates were produced in accordance with ASTM D7264 standard. The tensile test was performed in order to see the mechanical properties of the composite beams. The results showed that the optimum amount of CNT was 0.3% based on the tensile capacity. The capacity was significantly reduced when 0.4% CNT was utilized. Moreover, the experimental results are compared with Finite Element Models using ABAQUS. Hashin Failure Criteria was utilized to predict the tensile capacity. Good conformance was observed between experimental and numerical models. More importantly is that Young' Moduli of the specimens is compared with the prediction Halpin-Tsai and Mixture-Rule. Although Halpin-Tsai can accurately predict the Young's Moduli of the specimens, the accuracy of Mixture-Rule was significantly low.
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    Experimental tensile test and micro-mechanic investigation on carbon nanotube reinforced carbon fiber composite beams
    (Techno-Press, 2023) Madenci, Emrah; Ozkilic, Yasin Onuralp; Hakamy, Ahmad; Touns, Abdelouahe
    Carbon nanotubes (CNTs) have received increased interest in reinforcing research for polymer matrix composites due to their exceptional mechanical characteristics. Its high surface area/volume ratio and aspect ratio enable polymer-based composites to make the most of its features. This study focuses on the experimental tensile testing and fabrication of carbon nanotube reinforced composite (CNTRC) beams, exploring various micromechanical models. By examining the performance of these models alongside experimental results, the research aims to better understand and optimize the mechanical properties of CNTRC materials. Tensile properties of neat epoxy and 0.3%; 0.4% and 0.5% by CNT reinforced laminated single layer (0 & DEG;/90 & DEG;) carbon fiber composite beams were investigated. The composite plates were produced in accordance with ASTM D7264 standard. The tensile test was performed in order to see the mechanical properties of the composite beams. The results showed that the optimum amount of CNT was 0.3% based on the tensile capacity. The capacity was significantly reduced when 0.4% CNT was utilized. Moreover, the experimental results are compared with Finite Element Models using ABAQUS. Hashin Failure Criteria was utilized to predict the tensile capacity. Good conformance was observed between experimental and numerical models. More importantly is that Young' Moduli of the specimens is compared with the prediction Halpin-Tsai and Mixture-Rule. Although Halpin-Tsai can accurately predict the Young's Moduli of the specimens, the accuracy of Mixture-Rule was significantly low.
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    Shear behaviour of reinforced concrete beams utilizing waste marble powder
    (Elsevier Science Inc, 2023) Basaran, Bogachan; Aksoylu, Ceyhun; Ozkilic, Yasin Onuralp; Karalar, Memduh; Hakamy, Ahmad
    Today, it has been determined that waste marble dust (WMD) is not evaluated and therefore creates environmental problems. For this reason, in this study, the usability of WMD in different proportions, in which waste materials are evaluated, was investigated. Thus, it is aimed to eliminate the existing environmental problems by ensuring the use of WMD in reinforced concrete beams (RCBs). Pursuant to this motivation, an experimental program was carried out on 15 shear deficient RCBs, considering different WMD and stirrup spacing. While the proportion of WMD in the RCBs was chosen as 10%, 20%, 30% and 40% by weight, respectively, the stirrup spacing was considered as 270 mm, 200 m, and 160 mm. Concrete compressive strength (CCS) is generally adversely affected while WMD is used instead of cement at 10% or more rates. In RCB samples with the stirrup spacing of 270 mm, 200 mm, and 160 mm, 10%, 20%, 30%, and 40% WMD additives reduced the bearing capacity of the RCBs compared to the reference sample. It has been observed that ACI 318 (2019) and EC2 (2004) design regulations demonstrate excellent performance (maximum 85% success) in estimating shear strength up to 20% marble dust admixture in RCBs where the stirrup spacing is 200 mm and 160 mm. The results revelaed that using up to 5% of WMD instead of cement has approximately no negative influence on the CCS. Nevertheless, if this percentage is chosen as 10% or more, it has been found that the CCS is commonly destructively affected.
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    Thermal properties, microstructure analysis, and environmental benefits of basalt fiber reinforced concrete
    (Sage Publications Ltd, 2023) Qsymah, Ansam; Arbili, Mohamed Moafak; Ahmad, Jawad; Alogla, Saleh M.; Alawi Al-Sodani, Khaled A.; Hakamy, Ahmad; oezkilic, Yasin Onuralp
    Numerous scientists have studied basalt fiber (BF) reinforced concrete and found encouraging results. However, information is scattered, and compressive assessment is yet necessary to collect the data from prior research on BF, present research advancement, and future research guidelines of BF reinforced concrete. Furthermore, mostly research focus to review on strength and durability aspects of BF reinforced concrete while no researched focus on thermal properties, microstructure analysis and environmental benefits of BF reinforced concrete. Therefore, the primary focuses of this paper are BF treatment, BF reinforced concrete performance at high temperatures, microstructure analysis, environmental advantages, and application in civil engineering. Results show that BF-reinforced concrete performs much better than traditional concrete at high temperatures. Additionally, the use of BF enhanced the heat conductivity of concrete. BF addition to concrete seems to have reduced interfacial transition zone (ITZ) fractures, according to a microstructure study. When opposed to traditional steel fibers, BFs may be thought as reinforcements that are less harmful to the environment. The study also highlights the significance of BFs in the building industry. The assessment also identified research gap research for further studies.