Sürdürülebilir Kalkınma Amaçları

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• MakaleYalnız künye2023/r/gumushane/14382
  Investigation of used PCM-integrated into building exterior walls for energy savings and optimization of PCM melting temperatures

  Terhan, Meryem; Ilgar, Gamze

  In the study, the effects on the building's thermal energy performance of using two different phase change materials (PCMs) integrated into the exterior walls at various thicknesses and melting temperatures have been investigated. Four exterior wall types have been designed by changing the position of PCM integrated into the exterior wall for the purpose to decrease heating and cooling energy demand. For each wall type, three different thicknesses (layers) have been studied and energy savings that PCM provided by decreasing the heating and cooling energy demands have been calculated on a monthly and annual basis. According to the energy simulation analyses, the configuration provided the highest heating energy savings (21.32 %) on an annual basis is the three-layer BioPCM27 integrated exterior wall with a melting temperature of 21 °C. The monthly optimum melting temperatures of PCMs have been determined based on the charge and discharge processes of PCM integrated into the exterior walls by evaluating the results of hourly energy simulation analysis. The annual average optimum melting temperature varies between 18 and 19 °C, depending on the exterior wall and material types. The three-layer (3L) InfiniteRPCM21C configuration (Type 3) has the best thermal energy performance among all exterior wall types, with 24.45 % total energy savings in the cooling season and 14.76 % in the heating season.

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• MakaleYalnız künye2021/r/gumushane/14745
  Additivity effect on properties of cemented coal fly ash backfill containing water-reducing admixtures

  Cavusoglu, Ibrahim; Yilmaz, Erol; Yilmaz, Ali Osman

  Cemented coal fly ash backfill (CCB), a flowable structure of coal fly ash, binding agent and mixing water, has been often employed in mining operations to offer ground support as well as waste disposal solutions. An appropriate CCB mass should have sufficient rheological (e.g., workability) and mechanical (e.g., strength and stability) characteristics. Chemical admixtures are well known to greatly enhance the pumpability and strength properties of cementitious materials. Thus, this work provides the effect of water-reducing admixtures (namely, Sikament MR 50 W and Sikament FFN) on characteristics of CCB materials manufactured at a constant slump value. The role of admixtures in CCB mix is to reduce the cement-related costs, to modify the properties of the hardened backfills, and to ensure the quality of the backfill during mixing, transporting, placing, and curing. These admixtures were used at a dosage of 1% and 2% by weight of anhydrous material on cement. Several laboratory tests including slump, setting time, uniaxial compressive strength, scanning electron microscopy and mercury intrusion porosimetry were undertaken on CCB samples to understand their fresh and hardened performance. Experimental results show that the admixtures used ensure the slump required to deliver CCB at low water/cement ratios, improve short- and long-term backfill strengths up to 33%, and decrease the total porosity of the tested CCB. The findings of this study also show that the admixture use in CCB leads to a significant decrease in the considered cement content and a remarkable increase in the mechanical strength. As a result, understanding the actual fresh and hardened properties of CCB remains crucial for the choice of the greatest acting backfill admixture and for a fruitful change from capable experimental results to the in-situ conditions.

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• MakaleYalnız künye2018/r/gumushane/15173
  Experimental study on cement-treated and untreated RAP blended bases: Cyclic plate loading test

  Seferoğlu, Ayşegül Güneş; Seferoğlu, Mehmet Tevfik; Akpinar, Muhammet Vefa

  The asphalt surrounding the reclaimed asphalt pavement (RAP) aggregates decrease the performance characteristics of road layers. RAP material increases the permanent deformation potential of road layers under the traffic load. In this study, the performances of RAP-VA (Virgin aggregate) mixtures was tested using cyclic plate loading test by adding pozzolanic cement into mixtures in order to use RAP material at the rate of 100% and to minimize the permanent deformation in plant-mix base courses (PBC). The permanent surface deformations of base course were measured at different points throughout 100 loading cycles and all of the measurements were compared to that of base course prepared from 100% VA. The effect of RAP/cement rate of mixtures on the permanent deformations was examined and it was determined that the increase in RAP rate increased the permanent deformations but cement significantly decreased it. Moreover, considering the material costs of mixtures, the cost analysis was performed and the profit margins that using RAP and cement offers to constructors were computed.

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• MakaleYalnız künye2018/r/gumushane/14999
  Investigation of radiation absorption coefficients of lead-zinc mine waste rock mixed heavy concrete at 662–1460 keV energy range

  Çullu, Mustafa; Bakırhan, Emir

  The objective of this study is to observe the radiation shielding efficiency of concrete produced by using the lead wastes that are stored in lead-zinc mines processing of which is not financially viable in the mines they are extracted from that have negative effects on the environment. Within this scope, concretes were produced to be used as radiation shield concretes. The samples were prepared by altering the amounts of heavy aggregates such as lead–zinc mine waste, Magnetite, Limonite, and Barite at 25%, 50%, and 75% ratios, and concrete samples were prepared in C16/20, C25/30, and C35/45 concrete strength grades to determine the effects of these grades on radiation absorption properties. In order to determine the radiation absorption coefficients, absorption coefficients at 662 keV, 1173 keV, 1332 keV, and 1460 keV energy levels from Cs-137, Co-60 and K-40 sources were determined by concrete slabs with dimensions of 20 × 20 × 5 cm.

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• MakaleYalnız künye2017/r/gumushane/13362
  Combustion properties of impregnated spruce (Picea orientalis L.) wood

  Şadiye Yasar, Ş.; Said Fidan, M.; Yaşar, Mehmet; Atar, Musa; Alkan, Elif

  Wooden material is one of the most commonly used construction materials since history of humanity due to its environment friendly and renewable natural source. This structure of wood material is also preferred because it is lightweight, easy to work, resistant to factors such as earthquake and fire, as compared to other used building materials. However, organic structure of the wooden material causes it to be affected negatively because of damages that might occur outdoors under inappropriate conditions. Due to this reason, in this study were investigated effects of various chemicals (impregnated and varnish type), used to prevent environmental damages (biotic, abiotic pests, fire etc.) on combustion resistance of the wood exposed to air conditions for a year. For this purpose, prepared Caucasian spruce (Picea orientalis L.) specimens were surface treated (synthetic and water-based varnish) after impregnated according to ASTM-D 1413-76 principles with various chemicals (Tanalith-E and Wolmanit-CB). Test specimens with impregnated, varnished and processless, were left in outdoor conditions for a year. Combustion experiment was conducted according to the principles in ASTM-E 160-50 combustion test standards. According to the results of the experiment, control and year specimens had close results in the weight loss. Weight loss was found be lower Wolmanit-CB impregnated specimens (92.12%) among the impregnated materials to synthetic varnish coated specimens (% 91.89) among the varnished specimens. It was determined that using Wolmanit-CB for impregnating and synthetic varnish for varnishing would be better according to the results. Furthermore, the amount of O2 (25.84 ppm) in control specimens in combustion with flame; the amounts of CO and CO2 (31787, 19.92 ppm respectively) in year specimens in combustion without flame and the amount of NO (54.65 ppm) in year specimens in glowing was observed to be the highest.

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• MakaleYalnız künye2016/r/gumushane/15113
  Determination of the effect of lead mine waste aggregate on some concrete properties and radiation shielding

  Çullu, Mustafa; Ertaş, Haydar

  The aim of this study is to determine the radiation absorption capacity of concretes produced from lead mine waste which cannot be processed economically as the lead content is low in the mines they are extracted. Lead mine waste (tallow) were exchanged at ratios of 25%, 50% and 75% respectively with barite and limestone aggregates and samples were prepared at C16, C25 and C35 classes. The compressive strength and the unit weight of the prepared samples were determined. The linear absorption coefficients of prepared concrete samples at 662 keV of energy were determined. In addition the relationship between the radiation absorption capacity and the compressive strength–unit weight was investigated. The experiments demonstrated that best absorption was in concrete samples with 100% barite content (100B). On the other hand in the concrete samples prepared from the mixture of limestone and lead mine waste aggregates, it was observed that radiation absorption capacity decreased due to decreasing amount of barite. In concrete samples prepared from the mixture of lead mine waste and limestone aggregates, it was observed that radiation absorption capacity increased due to increasing amount of mine waste aggregates in the concrete. As a result it was observed that lead mine waste aggregates do not absorb as much radiation as barite aggregates depending on the ratio increase of lead mine waste in the aggregate added to the concrete mixture. However the absorbed radiation amount was observed to be higher compared to limestone aggregates.

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• MakaleYalnız künye2016/r/gumushane/11374
  Effect of seasonal changes on the combustion characteristics of impregnated cedar (Cedrus libani A. Rich.) wood

  Fidan, M. Said; Yaşar, Ş. Şadiye; Yaşar, Mehmet; Atar, Musa; Alkan, Elif

  Wood is an irreplaceable material used as decorative and structural element both indoors and outdoors. When used as a structural material, wood has several superior characteristics in comparison to other structural constituents, although it is adversely affected by fires as well as biotic pests and abiotic effects. In this study, cedar (Cedrus libani A. Rich.) wood samples were impregnated using either Tanalith-E or Wolmanit-CB as detailed in ASTM-D 1413-76 and surface-treated using water-based or synthetic varnish. The impregnated and varnished samples were left outdoors with the aim of investigating the effect of seasonal changes. The samples were later subjected to combustion analysis as detailed in the combustion test standard ASTM-E 160-50. The results of the study indicated that the weight loss was lower during winter (87.82%), for samples that were impregnated using Wolmanit-CB (88.90%) and those that were treated with synthetic varnish (88.45%). On the other hand the O2 and CO2 contents were determined to be the highest in fall during combustion without flame (18.16% and 17.96%, respectively); the CO content was the highest during combustion without flame for the winter samples (28,907 ppm) and the NO content was the highest during combustion without flame for the spring samples (76.15 ppm). In conclusion, the winter samples that were impregnated using Wolmanit-CB and treated with synthetic varnish were determined to be safer to employ in areas with high fire risk.

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• MakaleYalnız künye2015/r/gumushane/13216
  Utilization of granulated marble wastes and waste bricks as mineral admixture in cemented paste backfill of sulphide-rich tailings

  Ercikdi, Bayram; Külekci, Gökhan; Yilmaz, Tekin

  This study presents the utilisation of granulated marble wastes (MW) as an additive (10-30 wt%) and waste bricks (WB) as replacement and additive (15-45 wt%) to ordinary Portland cement (OPC) for cemented paste backfill (CPB) of sulphide tailings. OPC was used as binder at 7 wt% dosage. Pozzolanic activity tests showed that the fineness of the WB samples, not the chemical composition, is the major factor affecting their pozzolanic activity. Although they do not exhibit any pozzolanic activity, the use of MW samples as an additive to OPC improves acid buffering capacity of CPB samples and enhances their short and long-term mechanical performance. The UCSs of CPB samples increased with increasing additive rates and decreased with increasing replacement ratios. All CPB samples produced the desired strength and durability when MW and WB were used as an additive to OPC. However, a binder dosage of >7 wt% was required to produce the desired 28-day strength of ≥0.7 MPa when the OPC was replaced by 15-45 wt% WB samples. The durability (i.e. no loss of strength) of CPB samples is closely inter-related with the calcination temperatures and glass phase content of WB.

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• MakaleYalnız künye2014/r/gumushane/11873
  The effects of chemical attacks on physical and mechanical properties of concrete produced under cold weather conditions

  Çullu, Mustafa; Arslan, Metin

  This study investigates the effects of corrosive conditions on the physical and mechanical properties of concrete produced in cold weather. 30% calcium nitrate and 5% hydroxyethylaminemixture (HEA) were used as additives in antifreeze. Within 15 min of placing the prepared concrete samples in molds, the samples were put in a deep freezer. They were exposed to frost at 0 C, -5 C, -10 C, -15 C and -20 C degrees in the deep freezer over two days. The samples were taken out of the freezer and removed from the forms one day later. They were cured in water at room temperature until the 28th day. The samples were then exposed to sulfuric acid of 5% concentration (H2SO4), magnesium sulfate of 7500 mg/L concentration (MgSO4), sodium sulfate of 5% concentration (NaCl), and corrosive cure and water-curing until the 120th day. At the end of the curing period, the permeable pore space volume, water absorption ratio, unit volume weight, capillarity ratio, impermeability, compressive strength, static modulus of elasticity, Poisson's ratio and tensile strength values of the concrete samples were determined. The results showed that the physical and mechanical properties of the concrete were negatively affected by the corrosive conditions.

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• MakaleYalnız künye2010/r/gumushane/15401
  Investigation of mechanical and mineralogical properties of mortars subjected to sulfate

  Çavdar, Ahmet; Yetgin, Şükrü

  The durability can be described as concrete's resistance to the destructive influences of a medium containing acid, sulfate and/or various chemicals and mechanical effects. The main objective of this study is investigation of mechanical and mineralogical properties of cement mortar with different pozzolanic compositions and subjected to sulfated medium. In the study, the mortars produced with cement samples having seven different compositions and varied with an air-entraining agent were subjected to the influence of sulfate. This study is supported by thin section and X-ray powder diffraction (XRPD) investigations, in addition to being subjected to the basic tests, such as compression and flexure. The most important findings obtained from the study are that the compact structure has more effective properties against sulfate effects for cement mortars than pozzolanic materials' effects and the highest pozzolanic material ratio is restricted about 25-30% by mass because this ratio is a boundary of mechanical properties.

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