Sürdürülebilir Kalkınma Amaçları
Yayınlar
- MakaleAçık Erişim2025Optimal Ratio of Steel and Polyester Fibers on the Mechanical Behavior of Alkali-Activated Concrete Produced by Industrial Waste Minerals
Aksüt, Yavuz Selim; Çullu, Mustafa; Yetgin, Şükrü
Alkali Activation Concretes (AAC) have many superior properties compared to Ordinary Portland Cement Concrete (OPC). However, it shows traditional concrete behavior with its brittleness. In this case, the tensile strength and flexural strength which are weak in addition to ductility is being studied to be increased by using various artificial and natural fibers. In this context, it is inevitable to conduct multifaceted research to improve the behavior of Fiber Alkali Activated Concrete (FAAC). In this study, 13 different mixes were made using steel and polyester fibers in different proportions by volume (0%; 0.25%; 0.50%; 0.75%; 1%) separately and hybrid. The mechanical properties of cubic (150 × 150 × 150 mm), cylindirical (100 × 200 mm) and prismatic (150 × 150 × 600 mm) specimens were determined including compressive strength, modulus of elasticity and poison ratio, splitting tensile strength and flexural strength (toughness-energy absorption capacity and modulus of rupture). crack formation in concrete occurs early and a significant decrease in strength is observed due to the high flexibility and low flow resistance of polyester fibers. Steel fibers with high strength and higher yield strength were used in hybrid form to solve this problem. It was revealed that the blend ratio that contributed the most to the mechanical behavior of the specimens was the case where the fibers were used as hybrid at a ratio of 1% by volume evaluation from both the experimental results and the optimization.
- MakaleYalnız künye2025Durability properties of fiber-reinforced geopolymer concrete with natural and industrial waste mineral admixtures
Aksüt, Yavuz Selim; Çullu, Mustafa; Yetgin, Şükrü
In this study, ground granulated blast furnace slag (GGBFS) and quarry rock dust (RD), both industrial and natural mineral wastes were used as binder materials in geopolymer concrete. The influence of these mineral admixtures on the concrete’s durability under aggressive environmental conditions was investigated. Steel, polyester, and hybrid fibers were incorporated at volume fractions of 0%, 0.25%, 0.50%, 0.75%, and 1.0% to further enhance durability performance. Freeze-thaw and sulfate resistance tests were carried out to evaluate the effects of fiber type and content on the durability behavior of the geopolymer concrete. The test results showed that the mineral waste-based binder system itself offered considerable durability while the addition of fibers significantly improved resistance to freeze-thaw cycles and sulfate attacks. Among all types, the geopolymer concrete with 0.5% polyester fiber exhibited the highest resistance to freeze-thaw while hybrid fiber usage provided a balanced enhancement across both test environments.
- MakaleAçık Erişim2024Performance of different fibre types in alkaline-activated concrete produced with industrial wastes: volcanic rock powder and blast furnace slag
Aksüt, Yavuz Selim; Külekçi, Gökhan; Çullu, Mustafa; Yetgin, Şükrü
The objective of the study is to determine the effects of different fibre types and ratios on the mechanical and physical properties of alkali-activated concrete (AAC) and to optimise important properties such as workability, unit weight, water absorption, compressive strength, modulus of elasticity and abrasion resistance of these concretes. Concrete samples were produced using steel and polyester fibres at ratios of 0.25%, 0.50%, 0.75% and 1%. The fibre ratios were varied, and various tests were conducted to determine the mechanical and physical properties of the concrete samples. The experiments clearly revealed the effects of fibre types and ratios on the performance of concrete. These results clearly demonstrate the effects of different fibre types and ratios on the mechanical and physical properties of AACs. Particularly noteworthy is the water-retaining property of polyester fibres, their effect on workability and their enhancing effect on abrasion resistance. The effects of steel fibres on compressive strength and modulus of elasticity are more pronounced, but they may present disadvantages in terms of workability and abrasion resistance. It is observed that mixed fibre usage provides a good balance in some properties. This study provides a roadmap for evaluating sustainable material options in the concrete industry and guiding future research.
- MakaleYalnız künye2010Investigation 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.
- MakaleYalnız künye2010Investigation of abrasion resistance of cement mortar with different pozzolanic compositions and subjected to sulfated medium
Çavdar, Ahmet; Yetgin, Şükrü
The durability phenomenon for concrete, or cement mortar, has gained attention recently as one of the important mechanical properties. It can be described as concrete's resistance to the destructive influences of a medium containing acid, sulfate and/or various chemicals and mechanical effects, like abrasion. Most of the studies attempted to improve these individual properties in concrete. However, concrete can be subjected to two or more of these effects simultaneously. In this 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 and abrasive effects simultaneously. In this study, several examples were evaluated using samples cured for six different periods throughout one year. This study is supported by thin section and XRPD investigations, in addition to being subjected to the basic tests, such as compression, flexure and abrasion. If the most important findings obtained from the study are summarized, it is seen that a compact cement matrix is more effective against both sulfate and abrasive effects than mineral additives. The mortars subjected to coupled (sulfate and abrasive) effects show less durability if compared to ones cured in water and later abraded.
- MakaleYalnız künye2008The effects of the fiber contents on the mechanic properties of the adobes
Yetgin, Şükrü; ÇAVDAR, Özlem; Çavdar, Ahmet
In this study, compression and tensile tests were conducted for five different adobe mixtures. The important part of this study consisted of uniaxial compressive tests done with natural fiber mixtures. Thus, the results obtained from mechanical tests were presented in the form of stress-strain graphs. In addition, mechanical properties were related to the water content for workability, unit weight and fiber contents and discussions were given. The results show that as fiber content increases, compressive and tensile strengths decrease, and shrinkage rates decrease.
- MakaleYalnız künye2007Availability of tuffs from northeast of Turkey as natural pozzolan on cement, some chemical and mechanical relationships
Çavdar, Ahmet; Yetgin, Şükrü
At Northeast of Turkey, it is possible to find plenty of volcanic origin rocks and rich natural pozzolan beds. In this study, the pozzolanic activities of six types of different tuff samples taken from Trabzon and Bayburt regions (Northeast of Turkey) were examined according to the related standard and it was determined that the compressive strengths were varying between 6.7-11.0 MPa. In addition, the chemical compositions of these samples, except one, were consistent with the related standard. On the other hand, the results obtained from these studies were that increase in the proportion of SiO2 in the pozzolan increases the pozzolanic activity.