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    Experimental study on compressive behavior and failure analysis of composite concrete confined by glass/epoxy ± 55° filament wound pipes
    (Elsevier Sci Ltd, 2018) Gemi, Lokman; Koroglu, Mehmet Alpaslan; Ashour, Ashraf
    This paper investigates the strength and ductility of concrete confined by Glass/Epoxy +/- 55 degrees Filament Wound Pipes (GFRP) under axial compression. A total of 24 cylindrical specimens were prepared with expansive and Portland cements, properly compacted and un-compacted for different composite fresh concrete matrix. Test results showed that compressive strength and axial deformation at failure of concrete confined with GFRP tubes increased by an average of 2.85 and 5.57 times these of unconfined concrete, respectively. Macro and micro analyses of GFRP pipes after failure were also investigated. Debonding, whitening, matrix/transfer cracking, delamination and splitting mechanisms were detected at failure, respectively. The experimental results were also employed to assess the reliability of design models available in the literature for confined concrete compressive strength.
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    Mechanical properties of self-compacting concrete with recycled bead wires
    (Pontificia Univ Catolica Chile, Escuela Construccion Civil, 2019) Koroglu, Mehmet Alpaslan; Ashour, Ashraf
    This paper investigates the properties of self-compacting concrete with waste steel bead wires obtained as a result of the separation of waste tires. Waste steel bead wires were added to concrete between 1% and 5% by weight with an increment of 1%. In total, 54 cubes, 6 cylinders and 6 beams were cast, cured and tested in according to various standards to obtain the compressive, splitting tensile and flexural strengths, respectively. In addition, 6 cubes were left in salty water solution with a salt concentration of 4% for 120 days and tested in compression. A scanning electron microscopy (SEM) was also conducted on samples after failure. Test results showed that short time corrosion of steel fibers does not affect the mechanical properties. Also, the increase in the ratio of steel fiber was found to contribute positively to the mechanical properties of concrete up to 4%, beyond which, mechanical properties were reduced. Finally, in the samples subjected to bending tests, it has been found that a 6-fold increase in bending strength compared to the reference (non-fiber) sample was achieved in case of steel fiber ratio of 4% and 5%.