Sürdürülebilir Kalkınma Amaçları

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• MakaleAçık Erişim2016/r/gumushane/13084
  Use of polyvinyl chloride (PVC) powder and granules as aggregate replacement in concrete mixtures

  Bolat, Hakan; Erkus, Pinar

  Concrete is one of the materials in which polymer wastes are utilized. Generally, these wastes are added at specific rates in scientific studies but an important problem of waste polymers is size irregularity. Even when consistent dosage rates are used, variations in polymer size can lead to variability in the physical and mechanical properties of the concrete produced. The aim of this study is to determine physical and mechanical properties of polyvinyl chloride (PVC)-containing concretes. In order to produce normal and high strength concretes, 10%, 20%, and 30% replacement ratios of PVC powder and granules by volume of aggregate are used. Slump, fresh and hardened densities, compressive strength, capillary water absorption, and abrasion were tested on all concrete types. As the PVC ratio increases, important changes are seen in all physical and mechanical concrete properties. The unit weights of the 10%, 20%, and 30% replacement PVC powder concretes are lower by ∼4%, 8%, and 13%, respectively, as compared to the reference mixtures, and the replacement PVC granule concretes are lower by ∼2%, 4%, and 7%. Compressive strength test results showed similar trends. As PVC replacement increases, the capillary water absorption decreases between 10% and 50%, and abrasion decreases between 27% and 77%.

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• MakaleAçık Erişim2016/r/gumushane/11330
  Investigation of pozzolanic activity of volcanic rocks from the northeast of the Black Sea

  Çullu, Mustafa; Bolat, Hakan; Vural, Alaaddin; Tuncer, Ertan

  Mineralogical and chemical properties, as well as the pozzolanic activities, of the volcanic rocks in the northeast of the Black Sea were examined. Physical and mechanical tests were conducted on samples collected from the study area and the feasibility of using volcanic rocks as pozzolanic admixture in the concrete industry was investigated. Mortar samples containing admixture in the ratios of 0%, 10%, 20%, 30%, 40%, and 50% were prepared by keeping fineness of pozzolanic admixtures fixed. By using these mortar samples, prismatic mortar samples of 4×4×16 cm were prepared and the samples were cured in water. Their 7-, 28-, and 90-day tensile strengths, compressive strengths, and ultrasonic pulse velocity were determined. As a result, it was determined that volcanic rocks can be used to produce blended cement by considering their specific gravity, pozzolanic activities, and compressive strengths. It was noted that increase in trass rate significantly reduced tensile and compressive strength of cement in the early stage as expected.

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• MakaleAçık Erişim2011/r/gumushane/15629
  Frequency optimization of laminated skewed open cylindrical shells

  Topal, Umut; Uzman, Ümit

  This paper deals with frequency optimization of symmetrically laminated skewed open cylindrical shells. The design objective is the maximization of the fundamental frequency and the design variable is the fiber orientations. The firstorder shear deformation theory (FSDT) is used for the finite element solution of the shells. The modified feasible direction (MFD) method is used for the optimization routine. For this purpose, a program based on FORTRAN is used. Finally, the numerical analysis is carried out to investigate the effect of skew angles, length to radius ratios, subtended angle and boundary conditions on, the optimal designs and the results are compared.

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• MakaleAçık Erişim2010/r/gumushane/13117
  Effect of rectangular/circular cutouts on thermal buckling load optimization of angle-ply laminated thin plates

  Topal, Umut; Uzman, Ümit

  This paper deals with thermal buckling load optimization of symmetrically laminated angle-ply thin plates with centrally located different cutouts subjected to a uniform temperature load rise. The optimum results are given for maximum buckling temperature and the fibre orientation is adopted as design variable. The results are obtained for the various cutout geometries such as rectangle and circle. The modified feasible direction (MFD) method is used for the optimization routine. Therefore a program based on FORTRAN is used. Finally, the effects of cutout areas, plate aspect ratios and boundary conditions on the optimum results are demonstrated.

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