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Sürdürülebilir Kalkınma Amaçları

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• MakaleAçık Erişim2026/r/gumushane/16536
  Formulation of mechanical properties of hybrid fiber alkali-activated concretes by data analysis

  Aksut, Yavuz Selim; Yetgín, Sukru

  In this study, ground blast furnace slag (GBFS) and waste volcanic rock dust (RD) produced in a natural stone processing plant were used as binders. The binders were activated with Sodium Hydroxide (NaOH) and Sodium Silicate (Na2SiO3) to produce two types of concrete: alkali-activated concrete without fibers (AAC) and alkali-activated concrete with fibers (FAAC). In the production of concrete, steel and polyester fibers were used separately and hybrid at 0.25%, 0.50%, 0.75% and 1.0% by volume and a total of 117 15x15x15 cm cube specimens were produced. The mechanical properties of the specimens were evaluated by concrete surface hardness, ultrasonic pulse velocity and concrete compressive strength tests at 3, 7 and 28 days. The results obtained using non-destructive test methods were matched with concrete compressive strength values using various empirical formulas. Calculated concrete compressive strength values and actual concrete compressive strength values were compared using data analysis method. As a result, it was observed that there was a very significant correlation between the experimental compressive strength and the combined method in which 7-day surface hardness and ultrasound transmission rate were used together to calculate the compressive strength.

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• MakaleAçık Erişim2026/r/gumushane/19479
  Endüstriyel/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.

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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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• MakaleYalnız künye2026/r/gumushane/13524
  Mechanical 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.

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• MakaleYalnız künye2026/r/gumushane/12149
  Analysis 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.

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• MakaleYalnız künye2025/r/gumushane/16739
  Modeling 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.

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• MakaleAçık Erişim2025/r/gumushane/14352
  Optimal 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.

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• MakaleYalnız künye2025/r/gumushane/13973
  Durability 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.

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• MakaleAçık Erişim2025/r/gumushane/12431
  Flexural 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.

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• Doktora TeziAçık Erişim2024/r/gumushane/21574
  Alkali aktivasyon yöntemiyle doğal ve endüstriyel atık mineralli lifli kompozit geliştirilmesi

  Yavuz Selim Aksüt

  Beton endüstrisinde kullanılan çimentoya alternatif olarak daha ekonomik ve çevreci bir bağlayıcı yapı malzemesi geliştirmek için pek çok araştırmacı çalışmaktadır. Bu amaç doğrultusunda çimentosuz olarak üretilen alkali aktivastonlu beton (AAB) adı verilen daha çevreci ve ekonomik yeni bir yapı malzemesi geliştirilmeye yönelik çalışmalar her geçen gün artarak devam etmektedir. Alkali aktivasyon yöntemi ile üretilen betonlar, yüksek mekanik performans, düşük enerji giderleri, düşük kirletici gaz emisyonları (CO2, SO2, NO3 vb.) ve çevrenin daha az tahribi (doğal kaynaklar yerine atıkların kullanımı) gibi kazanımlar sunmaktadır. Ayrıca, atık malzemelerin kullanımıyla, atıkların çevreye verdiği zararlar ve depolama problemleri de azalmaktadır. Bu bağlayıcılar, normal portland çimento ve bunlarla üretilen betonlara göre daha erken ve daha yüksek dayanım, daha düşük hidratasyon ısısı ve agresif kimyasallara karşı daha yüksek dayanıklılık gibi birçok teknik üstünlüğe sahiptir. Tüm bu katkılar dikkate alındığında temel bir yapı malzemesi olan betonun geliştirilmesine yönelik çalışmaların sürdürüleceği açıkça görülmektedir. Bu çalışmada temel bağlayıcı olarak çimento yerine öğütülmüş yüksek fırın cürufu (ÖYFC) ve buna ek olarak ince malzeme ise Erzincan yöresinde bulunan taş ocağı işletmesi atık malzemesi kullanılmıştır. Ayrıca, kullanılan bağlayıcının Sodyum Hidroksit (NaOH) ve Sıvı Sodyum Silikat (Na2SiO3) kullanılarak aktive edilmesi sonucunda üretilen alkali aktivasyonlu betonların (AAB) fiziksel ve mekaniksel özelliklerinin ortaya konulması ve farklı lif türlerinin ayrık ve katışık lif kullanımları sonucunda üretilen betonların dayanım ve dayanıklılık özelliklerine etkilerinin ortaya çıkarılmasına çalışılacaktır. Tüm bu çalışmalar neticesinde çimentoya alternatif olarak yerel kaynakların kullanılmasının yolu açılmış olacaktır. Elde edilen deneysel sonuçlara bağlı olarak numunelerin davranışları yorumlanıp, en iyi başarımı gösteren numune bileşimi belirlenecektir. Anahtar Kelimeler: Alkali aktivasyonlu beton, Atık malzeme, Bağlayıcı, Dayanım ve dayanıklılık özellikleri, Katışık lif kullanımı

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