Sürdürülebilir Kalkınma Amaçları

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• MakaleYalnız künye2026Scopus SJRQ1/r/munzur/1071
  Enhancing durability of slag-based alkali-activated composites with dunite sand and carbon fiber: Sulfate, freeze–thaw, and thermal resistance optimization

  Benli, Ahmet; Bürlükkara, Sadullah; Öz, Ali; Karataş, Mehmet; Kaplan, Gökhan

  The replacement of natural river sand with sustainable alternatives is essential to reduce environmental degradation associated with aggregate extraction. In this context, dunite sand (DS), a magnesium-rich ultramafic mineral, was investigated as an eco-efficient fine aggregate in thermally cured slag-based alkali-activated composites (AACs), in combination with carbon fiber (CF) reinforcement. The study aims to clarify how aggregate substitution and fiber addition interact to control matrix densification, crack-bridging efficiency, and durability under aggressive conditions. Sixteen mixtures incorporating varying DS (0–100%) and CF (0–1.00%) contents were prepared and cured at 80°C to promote rapid slag activation and microstructural development. Mechanical performance, high-temperature resistance, sulfate durability, and freeze–thaw behavior were systematically evaluated. The results demonstrate that moderate DS substitution (~25%) significantly improves matrix compactness and interfacial quality through a micro-filler effect, leading to enhanced strength and durability. CF effectively bridge micro cracks and improve flexural and thermal performance; however, excessive fiber contents impair workability and increase porosity due to fiber clustering. Durability results confirm that optimized DS–CF combinations reduce thermal degradation, limit sulfate-induced deterioration, and enhance resistance to cyclic freezing. Overall, 25% DS replacement combined with limited CF content (≤0.50%) provides the best balance between mechanical performance and durability. The findings highlight the importance of controlling aggregate–fiber synergy and curing strategy to develop durable, thermally stable, and sustainable alkali-activated composites for harsh service environments.

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  AtıfScopus5·WoS4·OpenAlex4

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• MakaleAçık Erişim2026Scopus SJRQ1/r/munzur/852
  Enhancing the mechanical and durability properties of fly ash/GGBS-based geopolymer mortars using dunite and polypropylene fibers

  Cemalgil, Selim; Gülmez, Nihan; Yön, Merve Şahin; Karataş, Mehmet

  Polypropylene (PP) fiber-reinforced geopolymer mortar reduces the high brittleness of conventional geopolymer made with natural aggregates. However, the effects of different precursor materials on the performance of PP fiber-reinforced self-compacting geopolymer mortar (SCGM) remain unclear. This study investigates the feasibility of using dunite (D), a magnesium-rich ultramafic rock with consistent mineralogy and low processing energy demand that enhances thermal stability and durability, as an alternative precursor for fly ash (FA)/ground granulated blast furnace slag (GGBS)-based geopolymers. The study examined the workability, flexural and compressive strengths, and sorptivity of mortars cured at 20 ± 2°C and 60 ± 5% relative humidity, as well as their durability under freeze–thaw cycles and high-temperature exposure. Interfacial interactions between aggregates and the geopolymer matrix, along with microstructural and morphological changes caused by fire, were analyzed using scanning electron microscopy (SEM). X-ray diffraction (XRD) and thermogravimetric analysis (TGA) were also performed for detailed material characterization. The mix containing 30% dunite exhibited the highest flexural strength, reaching 5.70 MPa at 28 days, the highest among all mixes. Under fire exposure, the mix containing 10% dunite significantly reduced mechanical strength loss and retained about 33.3% higher residual flexural strength than the FA–slag control mix at 600°C.

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  AtıfScopus1·WoS1·OpenAlex1

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• MakaleYalnız künye2026Scopus SJRQ1/r/munzur/773
  Mechanical and durability properties of sustainable alkali-activated mortars with ceramic insulator waste and andesite powder as partial substitutes for GBFS

  Cemalgil, Selim; Yön, Merve Şahin; Dener, Murat; Karataş, Mehmet

  This study explores the use of andesite powder (AP) and ceramic waste powder (CWP), derived from discarded electrical insulators, as supplementary precursors to ground granulated blast furnace slag (GBFS) in alkali-activated self-compacting mortars. The originality of the work lies in the combined utilization of these regionally sourced aluminosilicate wastes in binary and ternary binder systems, aiming to reduce GBFS dependency while ensuring adequate mechanical and durability performance. AP and CWP were used to replace GBFS at up to 50%, and the mixtures were evaluated for flowability, mechanical strength, density, porosity, water absorption, and capillary sorptivity. Durability was assessed through freeze–thaw cycling and high temperature exposure, and microstructural characteristics were examined using scanning electron microscope analysis. Results showed that while partial substitution with AP or CWP reduced compressive strength compared to the GBFS control, the incorporation of CWP in ternary systems partially compensated for the strength losses associated with AP. High temperature resistance improved markedly with increased CWP content; at 900°C, the 50% CWP mixture retained 44% of its original compressive strength, in contrast to 8% for the control. Although all mixtures containing waste exhibited reduced freeze–thaw resistance, mortars containing CWP exhibited superior performance compared to those with only AP. These findings highlight the potential of CWP, particularly in ternary systems, for developing sustainable alkali-activated mortars.

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  AtıfScopus16·WoS14·OpenAlex12

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• MakaleYalnız künye2026Scopus SJRQ1/r/munzur/621
  High-temperature, freeze–thaw, and sulfate resistance of mortars incorporating ternary blends of fly ash, chromite, and waste glass

  Gülmez, Nihan; Kanellopoulos, Antonios

  The demand for sustainable construction materials promotes the use of industrial waste in cement-based systems. This study examines mortars incorporating fly ash (FA) (0%, 7.5%, and 15%), waste glass, and chromite aggregates for mechanical and durability performance. Specimens underwent compressive strength, freeze–thaw, high-temperature, sulfate attack, and ultrasonic pulse velocity tests, while microstructure was characterized by x-ray diffraction, thermogravimetric analysis, and scanning electron microscopy–energy-dispersive spectroscopy. Mortars with 7.5% FA exhibited relatively high compressive strength and improved freeze–thaw resistance. The combined use of chromite and FA improved strength retention at 800°C, reaching 23 MPa with 7.5% FA and 50% chromite. The greatest sulfate resistance occurred in mortars containing 15% FA and 15% waste glass, maintaining compressive strengths of 61 and 70.9 MPa after MgSO4 and Na2SO4 exposure, respectively.

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• MakaleAçık Erişim2025Scopus SJRQ1/r/munzur/1545
  Evaluating the high-temperature resistance of self-compacting mortar incorporating waste andesite powder as a mineral admixture

  Karataş, Mehmet; Bozcan, Emre; Dener, Murat

  Significant amounts of waste material are generated at various stages of andesite stone processing, including mining, cutting, and polishing. Despite this, limited research has been conducted on the potential use of waste andesite powder (WAP) as a mineral admixture. The impact of WAP on the high-temperature resistance of cement-based composites remains largely unexplored. This study aims to evaluate the benefits of incorporating WAP as a partial substitute for Portland cement. Self-compacting mortars (SCMs) with varying WAP replacement rates (5%–30%) were produced and subjected to temperatures of 300°C, 600°C, and 900°C. Additionally, ternary mixtures of WAP and silica fume were produced for comparative analysis. The results showed that SCMs containing up to 10% WAP exhibited higher 90-day compressive strength compared to the control sample. Furthermore, WAP inclusion improved high-temperature resistance, and the use of WAP at higher replacement rates was feasible when combined with mineral admixtures possessing high pozzolanic activity, such as silica fume.

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  AtıfScopus6·WoS3·OpenAlex4

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