Sürdürülebilir Kalkınma Amaçları

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• MakaleAçık Erişim2026/r/gumushane/13548
  The effect of mine waste ratio and curing duration on the mechanical properties of ground granulated blast furnace slag-based geopolymer mortars

  Aksüt, Yavuz Selim; Nas, Evin; Sünnetçi, Kadir; Kaya, Yusuf

  This study investigates the mechanical and microstructural behavior of ground granulated blast furnace slag (GGBFS)-based geopolymer mortars in which mining waste (MW) was used as a partial binder replacement (0–30%) under ambient water curing for 7–90 days. Increasing MW content reduced workability and slightly prolonged setting due to its coarser and less reactive characteristics. Mechanical performance improved with curing time and mixtures with moderate MW levels achieved the best strength and microstructural densification. Water absorption and porosity decreased with age, reflecting progressive gel formation. Scanning electron microscope–X-ray diffraction (SEM-XRD) analyses verified matrix densification and enhanced gel development at intermediate MW ratios. Overall, the findings show that controlled MW incorporation can optimize the balance between strength, pore structure and sustainability, enabling ambient cured GGBFS-based geopolymers without thermal curing. The study provides new insights by using MW as a binder phase replacement while preserving precursor chemistry, a rarely explored approach.

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• MakaleAçık Erişim2009/r/gumushane/15799
  Water quality modeling and dissolved oxygen balance in streams: A point source Streeter-Phelps application in the case of the Harsit stream

  Nas, S. Serkan; Nas, Evin

  The Harsit Stream flowing into the Black Sea is an important watershed in the northeastern part of Turkey. The monthly averages of dissolved oxygen, carbonaceous biochemical oxygen demand, temperature, pH, total suspended solids, total phosphorus and total nitrogen were obtained for the water samples taken from the Tekke, Akcakale and Haciemin sites of the Harsit Stream. Water quality parameters were analyzed and evaluated according to the WHO standards and the Turkish Water Pollution Control Regulation. Initially, the variations in the dissolved oxygen profile were determined from dissolved oxygen, temperature and carbonaceous biochemical oxygen demand measurements by using the point source Streeter-Phelps equation. Critical dissolved oxygen deficit values were calculated for the monthly average from January-December 2005, which are below the limit value (4 mg L-1) excluding April (7.26 mg L-1) and May (5.98 mg L-1) in the Harsit Stream, resulting in it having second class water quality in terms of dissolved oxygen concentration, temperature, pH and biochemical oxygen demand. It is also seen that the minimum dissolved oxygen limit value (8 mg L-1), which is a desired quantity for drinking water, is under the limit value for all months in the case of the water mixture. In particular, during the summer months, the consumption speed of oxygen is greater than the production speed of oxygen with increasing temperature and decreasing discharge, and negative values (anoxia) of dissolved oxygen sag are seen. These situations call for significant precautions and treatment criteria.

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• MakaleYalnız künye2008/r/gumushane/14153
  Effects of some water quality parameters on the dissolved oxygen balance of streams

  Nas, S.S.; Bayram, A.; Nas, E.; Bulut, V.N.

  The Galyan Stream basin supports the water of Atasu Dam, which will provide domestic water for Trabzon province in Turkey. The Galyan Stream empties into Deǧirmendere Stream and their water into the Black Sea that these streams are important watersheds in northeastern Turkey. Water samples were periodically taken from Temelli site (Galyan Stream), Deǧirmen site (Kuştul Stream) and Çiftdere site (Galyan Stream). In this study, at first, variations of dissolved oxygen profile are determined from dissolved oxygen, temperature and carbonaceous biochemical oxygen demand measurements by using Point Resources Streeter-Phelps equation. Water samples are taken from the Galyan and Kuştul Streams. Water quality parameters were analyzed for both streams and evaluated according to the Turkish Water Pollution Control Regulation (TWPCR). Critical dissolved oxygen deficiency values, which were calculated for monthly average (2004 April-2005 January) and annual averages (2000-2004), are seen to be over the limit value in the Galyan Stream having first class water quality in terms of dissolved oxygen concentration, temperature and biochemical oxygen demand. In the following it is disclosed that treatment isn't required. That study shows that minimum dissolved oxygen limit value (8 mgL-1), which is desired in domestic waters, is under the limit value in July, August and September months in case of a mixture.

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• MakaleYalnız künye2008/r/gumushane/13975
  Laboratory study of expanded polystyrene (EPS) geofoam used with expansive soils

  Ikizler, S. Banu; Aytekin, Mustafa; Nas, Evin

  The reduction of transmitted lateral swelling pressures on retaining structures constructed in expansive soils is investigated. Swelling pressures will develop if the soil is not allowed to swell freely. The magnitude of swelling pressure depends on the degree of expansion permitted. When a little soil expansion is allowed, the swelling pressure may be decreased considerably relative to the case of no expansion. This study examines the role of expanded polystyrene (EPS) geofoam in accommodating soil expansion and hence reducing swelling pressures on adjacent structures. Several hypothetical cases are presented whereby reductions on the transmitted lateral pressures due to expansive soils are examined for different thickness of EPS geofoam.

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