Sürdürülebilir Kalkınma Amaçları
Yayınlar
- MakaleAçık Erişim2026Endüstriyel/Madensel Atıklardan Elde Edilen Geopolimer Bileşenler Üzerinde Taguchi Metodu Yardımıyla Farklı Üretim Parametrelerinin Etkisinin Belirlenmesi
Çavdar, Özlem; Aksüt, Yavuz Selim; Temizer, Hülya
Çimento üretimi kaynaklı CO2 sera gazının ve diğer kirleticilerin başta iklim değişikliği ve küresel ısınma olmak üzere, çevre ve insan sağlığını tehdit ettiği bilinmektedir. Bu çalışmada, geopolimer kompozit harçlar üzerinde farklı üretim parametrelerinin etkisi incelenmiştir. Ana bağlayıcılar olarak yüksek fırın cürufu ve uçucu kül içeren geopolimer yapılara ek olarak endüstriyel ve madensel katkı maddeleri ilave edilmiştir. Bağlayıcılar üzerinde kür sıcaklığı, kür süresi ve endüstriyel /madensel atıklar gibi birçok parametrenin etkisi araştırılmıştır. Bu kapsamda Taguchi metodu kullanılarak 3 farklı seviye ve 6 farklı parametre ile L27 (36) ortogonal matris oluşturulmuştur. Çalışmada, üç farklı molar oranı (8M,10M,12M) olmak üzere sodyum hidroksit çözeltisi ile sodyum silikat kullanılmıştır. 56 gün atmosferik kür uygulanan numunelere ANOVA analizleri de yapılmıştır. Taguchi ve ANOVA istatistiksel sonuçlarına göre, geopolimer numuneler üzerinde en etkili parametrenin kür sıcaklığı olduğu belirlenmiştir. ‘En büyük en iyidir’ kriteri sonuçlarına göre hazırlanan sinyal/gürültü (S/N) oranı verilerinden en etkin sıcaklığın 75⁰C olduğu anlaşılmaktadır.
- MakaleAçık Erişim2026The 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.
- MakaleYalnız künye2026Mechanical properties of polypropylene fiber-reinforced shotcrete based chromite flotation waste using a nondestructive testing method
Aksüt, Yavuz Selim; Seferoğlu, Mehmet Tevfik
This study examines the mechanical behavior and non-destructive assessment of shotcrete reinforced with polypropylene fibers (PPFs) and incorporating chromite flotation waste (CFW) as a partial substitute for fine aggregate. Shotcrete mixtures were prepared with four CFW replacement levels (0–30%) and four PPFs volume fractions (0–1%) and their compressive strength, splitting tensile strength and static modulus of elasticity were evaluated. Poisson's ratio and ultrasonic pulse velocity (UPV) were experimentally determined. The effect of fiber reinforcement and waste incorporation on the mechanical behavior was evaluated through statistical correlation, simple regression and multivariable predictive modeling approaches. The results showed that moderate PPFs contents (0.25–0.5%) generally enhanced compressive and tensile performance while excessive fiber dosage (1%) led to strength and stiffness reductions due to increased heterogeneity, fiber agglomeration and void formation at high CFW replacement levels. Increasing CFW content resulted in systematic reductions in UPV values with an average decrease of approximately 3–4% per 10% CFW replacement indicating changes in matrix continuity and internal structure. However, these UPV reductions were not directly proportional to losses in mechanical strength or elastic stiffness. Correlation analyses revealed weak to moderate relationships between UPV and mechanical properties confirming that UPV alone is insufficient to represent the complex behavior of fiber-reinforced, waste-based shotcrete systems. Simple UPV-based regression models exhibited limited predictive capability for both compressive strength (R2 ~ 0.16) and static modulus of elasticity (R2 ~ 0.002). In contrast, multivariable regression models incorporating normalized UPV, CFW replacement ratio and PPFs volume fraction together with their interaction terms, significantly improved prediction accuracy. The proposed models achieved high coefficients of determination (R2 ~ 0.86 for compressive strength and R2 ~ 0.97 for static elastic modulus) with substantially reduced root mean square error (RMSE) values. Finally, the findings demonstrate that UPV can be effectively used as a non-destructive indicator for estimating the strength and stiffness of PPFs reinforced shotcrete incorporating CFW only when material specific parameters are explicitly considered.
- MakaleYalnız künye2026Analysis of microstructural properties and durability characteristics of geopolymer mortars with mining waste
Aksüt, Yavuz Selim; Kaya, Yusuf; Sünnetçi, Kadir
The growing environmental concerns over resource depletion and carbon emissions from cement production have accelerated the search for sustainable alternatives to conventional concrete. In this context, geopolymers have emerged as promising binders, particularly through the utilization of aluminosilicate-rich industrial wastes to reduce environmental impact and support waste recycling. This study examines the mechanical and durability properties of geopolymer mortars produced by partially replacing ground granulated blast furnace slag (GGBFS) with mining waste (MW) at ratios of 0%, 10%, 20%, and 30%. The mixtures were activated using 10 M sodium hydroxide and sodium silicate under standard water curing conditions. Mechanical strength, ultrasonic pulse velocity (UPV), freeze–thaw resistance, and sulfate durability were evaluated. The optimum performance was obtained with 20% MW, which achieved a 30.4% increase in flexural strength and 18% in compressive strength at 7 days. This mixture also showed the lowest mass (10.69%) and strength loss (18.36%) after 50 freeze–thaw cycles. Scanning electron microscopy analysis confirmed enhanced gel formation and microstructural densification. The findings demonstrate that controlled use of MW not only improves durability but also promotes sustainable binder development in geopolymer technology.
- MakaleYalnız künye2025Modeling the Compressive Strength of Fiber-Reinforced Alkali-Activated Concrete Using Non-Destructive Methods in Short Curing Periods
Aksüt, Yavuz Selim; Çullu, Mustafa; Yetgin, Sukru
The indirect assessment of concrete compressive strength using non-destructive techniques, including the Schmidt rebound hammer and ultrasonic pulse velocity methods, is crucial for evaluating and tracking the strength of structural concrete used in construction and rehabilitation projects. However, studies focusing on alkali-activated concrete (AAC) remain insufficient. This study investigates the mechanical properties of fiber-reinforced alkali-activated concretes (FAACs) produced with short curing times, addressing this gap in the literature. Ground blast furnace slag (GBFS) was used as the binder, and waste volcanic rock dust (RD), produced in a natural stone processing plant, served as a fine filler. These materials were activated with sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) to produce alkali-activated concrete, both without fibers (AAC) and with fibers (FAAC). Steel fiber (SF) and polyester fiber (PYF) were used separately and in hybrid forms at 0.25%; 0.50%; 0.75%, and 1.0% volume fractions, resulting in a total of 117 cubic specimens (15x15x15 cm). The specimens' mechanical properties were evaluated using regression analyses based on data from Schmidt rebound number (RN), ultrasonic pulse velocity (UPV) non-destructive methods and uniaxial compressive strength (UCS) destructive tests. Optimized functions predicting compressive strength based on RN and UPV measurements were developed, highlighting the significant effects of fiber type, ratio, and mode of use. Additionally, multivariate prediction models were statistically developed using data from the three test methods.
- 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 Erişim2025Flexural Behavior and Sustainability of Dual-Waste Fiber-Reinforced Concrete Designed for Pavement Applications
Seferoğlu, Mehmet Tevfik; Aksüt, Yavuz Selim; Seferoğlu, Ayşegül Güneş
This study evaluates the mechanical performance and sustainability potential of fiber-reinforced concrete incorporating mine tailings as the fine aggregate and waste tire wire as the reinforcing fiber. The concrete mixtures contained 0.2%, 0.4%, and 0.6% waste tire wire with the natural fine aggregate replaced entirely with Pb-Zn-Cu tailings. The mixtures were tested for porosity, water absorption, compressive strength, splitting tensile strength, flexural strength, toughness, fracture energy, and ductility to assess their mechanical performance and durability. The mine tailings improved the microstructure and reduced water absorption, particularly with tire wire. Using waste tire wire improved the compressive, tensile, and flexural performance; in particular, W-6 showed a 18.2% rise in compressive strength and a more than twofold increase in flexural strength relative to the control mix. The flexural toughness and fracture energy rose by up to 161%, while the ductility peaked at a fiber content of 0.2%. These gains were attributed to fiber crack-bridging and post-cracking energy absorption. The dual-waste system also reduced porosity, improved durability, and demonstrated strong potential for rigid pavement applications such as highways, industrial yards, and airport runways that require high fatigue resistance and a long service life. Beyond technical performance, this approach offers a sustainable solution that lowers maintenance, reduces life-cycle costs, and aligns with circular economy principles.
- 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.
- MakaleAçık Erişim2023Vulnerability-Preventing Structures in Disaster Management: Polyurea Coating on Building Structural Elements
Kaya, Afşin Ahmet; Akduman, Öznur; Aksüt, Yavuz Selim
Numerous disasters occur due to the inability to manage risks arising from natural, technological, and human-induced hazards. As a result of these disasters, the magnification of incurred damages underscores the significance of the concept of risk management, an integral step in disaster management. Consequently, efforts to mitigate the adverse effects of earthquakes and other disasters are progressively increasing. However, endeavors aimed at reducing the damages inflicted by earthquakes and other disasters on structures, particularly earthquakes, are not yet at an adequate level. Presently, the importance of alternative solution models to counteract the forces exerted on structures during disasters like earthquakes is on the rise.In this study, unreinforced concrete blocks were coated with flexible polyurea, a state-of-the-art cladding material extensively used in various fields, at different thicknesses. Three-point bending tests were performed on the coated specimens. The data obtained from these tests were analyzed and evaluated. It was concluded that specimens coated with polyurea exhibited higher strengths compared to uncoated specimens. This study introduces the utilization of polyurea flexible composite material in structural elements as an alternative method within the spectrum of precautions taken to enhance the safety of structures against various disasters, primarily earthquakes.
- MakaleYalnız künye2017THE USABILITY OF VOLCANIC ROCKS FROM UPPER EUPHRATES PART IN THE EASTERN ANATOLIA REGION AS CONCRETE AGGREGATE
Aksüt, Yavuz Selim; Yetgin, Sukru
In this study; the engineering properties of volcanic rocks obtained from four different quarries in the province of Erzincan region in the Upper Euphrates Part in the Eastern Anatolia Region were investigated. In laboratory studies, the experiments including bulk and aggregate tests (bulk and dense unit weight, specific mass, water absorption, Los Angeles test for resistance to wear, freezing resistance and uniaxial compressive strength) were conducted on 5 volcanic samples according to the standards (Turkish Standard, British Standard and ASTM) and in the second stage, grading of concrete tests (grading of the concrete aggregates, concrete preparation, slump test, specific density of concrete, uniaxial compressive strength, modulus of elasticity, splitting tensile strength, abrasion resistance and capillarity) were performed on the concrete samples with volcanic aggregates. For fresh concrete composition, water/cement ratio was selected as the main variable providing homogeneous mixing and the highest strength to the concrete samples with a specific granulometry. Cylindrical concrete samples were produced with a variety of water/cement ratios cured for 7 and 28 days in water and their compressive strengths were assessed in the light of their physical and mechanical properties. The results obtained from aggregates and concrete tests, which were performed in line with the standards showed that especially Yassitepe-Dogu (YTD) sample, one of the volcanic rocks from Erzincan region can be used as concrete aggregate. It was observed that compressive strength of the concrete samples could satisfy C25/30 strength class and upper classes. In addition, it was understood that they can be used in highways, bridges, dams, buildings etc., especially as structural concrete.