Sürdürülebilir Kalkınma Amaçları

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• MakaleAçık Erişim2026Scopus SJRQ1/r/munzur/1515
  Optimization, high-temperature resistance, and sulfate durability of basalt powder–blended alkali-activated slag mortars

  Arslan, Furkan; Dener, Murat; Karataş, Mehmet; Benli, Ahmet

  This study investigates the feasibility of using basalt powder (BP), an industrial by-product with limited reactivity, as a partial substitute for granulated blast furnace slag (GBFS) in alkali-activated systems. A comprehensive experimental program was conducted in two stages: first, a systematic optimization was performed by varying mixture parameters, including BP content, alkali dosage, activator modulus, and curing temperature to evaluate compressive strength development; second, selected binder compositions were used to produce self-compacting mortars, which were further examined for flexural strength, high-temperature resistance, and sulfate durability. The results demonstrated that moderate substitution levels (up to 20–30 % BP) could achieve satisfactory compressive strength, particularly under elevated curing temperature (60 °C) with 8 % Na2O and low to moderate modulus values. At 300 °C, mixtures with 20 % BP exhibited strength enhancement due to additional geopolymerization, demonstrating superior thermal stability compared to the control. Crucially, the incorporation of BP enhanced sulfate resistance, with the 40 % BP mixture exhibiting a slight increase in compressive strength after long-term exposure, in contrast to the marked deterioration of the GBFS-only system. Consequently, this study demonstrates that BP can be effectively utilized as a sustainable binder component, offering a practical solution for waste management while enhancing the durability of alkali-activated mortars against aggressive conditions.

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  AtıfScopus15·WoS13·OpenAlex10

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• MakaleAçık Erişim2026Scopus SJRQ2/r/munzur/1482
  Sustainable self-compacting mortars: mechanical, durability and microstructural evaluation with cement replacement materials under aggressive environmental conditions

  Karabulut, Büşra; Yön, Merve Şahin; Karataş, Mehmet

  The aim of this study is to assess the mechanical, physical and durability properties of environmentally friendly self-compacting mortars produced using materials containing industrial waste and natural stone. The test series were produced by substituting diatomite (D) and C class fly ash (F) with Portland cement (PC) up to 30% by weight. To evaluate the workability, mechanical and durability properties of self-compacting mortars (SCM), a total of 19 series, one of which was a reference sample, were prepared. The samples, whose mechanical properties and durability properties were investigated under sulphate attack and freeze-thaw effects, were prepared as 40 × 40 × 160 mm, and the series, whose physical properties were examined, were prepared as 50 × 50 × 50 mm. Also, SEM/EDS (Scanning Electron Microscope - Energy Dispersive X-Ray) and XRD (X-Ray Diffraction) analyses were carried out to evaluate the microstructural properties of the mixtures. When the 90-day compressive strength results were examined, it was determined that the highest decrease in compressive strength compared to the control sample occurred in the D20F10 sample with a rate of 61%, and the least decrease occurred in the D5 series with a rate of 10%. When the losses in compressive strength were evaluated after 50 freeze-thaw cycles, it was determined that there was a 100% reduction in the binary and ternary series containing D15 and D20. After six months of sulphate exposure, the D5F25 sample exhibited the most significant compressive strength reduction at roughly 40%, whereas the D15F15 series experienced the least compressive strength decline at around 5%.

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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/1047
  Sustainable hybrid activation: Synergistic effects and optimization of one-part alkali-activated slag using sodium sulfate and sodium carbonate

  Orhan, Taha Yusuf; Balun, Bilal; Dener, Murat; Karataş, Mehmet

  The development of one-part alkali-activated materials (AAMs) using near-neutral and moderately alkaline salts offers a promising, low-carbon alternative to hazardous two-part systems. However, overcoming delayed reaction kinetics and setting anomalies remains a critical challenge. This study systematically investigates the fresh state, mechanical, and microstructural evolution of one-part slag mortars activated by sodium sulfate (Na2SO4), sodium carbonate (Na2CO3), and their hybrid combinations, adopting a hybrid binder approach through modification with calcium-rich additives (Portland cement, hydrated lime, and quicklime). Results demonstrate that while Portland cement ensures a controlled dissolution rate and balanced setting times across all environments, the incorporation of 7.5% quicklime in pure carbonate media triggers an instantaneous flash set. This extreme reactivity leads to a severe structural collapse, plunging the 90-day compressive strength to 16.11 MPa. Microstructural analyses (TGA and FTIR) suggest a link between this mechanical failure and a massive accumulation of unreacted portlandite (4.51% mass loss) rather than cohesive C-(A)-S-H gel formation, a degradation further corroborated by a drastic attenuation in ultrasonic pulse velocity (UPV). Conversely, the synergistic implementation of hybrid sulfate-carbonate activators effectively mitigates these anomalies. Sulfate ions buffer early-age kinetics to prevent flash setting-recovering the collapsed strength up to 29.16 MPa while carbonate ions facilitate sustained late-age matrix densification. Ultimately, tailoring specific calcium boosters within a hybrid activator framework presents a highly robust and potentially low-carbon framework for developing sustainable binders for practical on-site construction applications.

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  AtıfScopus3·WoS2·OpenAlex2

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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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• MakaleAçık Erişim2025/r/munzur/6193
  Nevşehir taşı tozunun kendiliğinden yerleşen harçlarda portland çimentosu ikamesi olarak kullanım potansiyelinin değerlendirilmesi

  Yon, Merve Sahin; Karataş, Mehmet; Demir, Mustafa

  Portland çimentosunun üretimi atmosferdeki karbondioksit emisyonlarının artmasına neden olmaktadır. Bu nedenle, Portland çimentosu yerine puzolanik özelliklere sahip doğal kaynakların ve atıkların kullanılması zorunlu hale gelmiştir. Bu makalede, kendiliğinden yerleşen harç yapımında Portland çimentosunun yerine kullanılabilecek doğal olarak oluşan puzolanik bir malzeme olan Nevşehir taşı tozunun etkinliği incelenmiştir. Portland çimentosu yerine %5, %10, %15 ve %20 oranlarında Nevşehir taşı tozu ilave edilerek hazırlanan harcın performansının değerlendirilmesi amacıyla bir laboratuvar çalışması yapılmıştır. Kendiliğinden yerleşen harcın başlangıçtaki mekanik performansını incelemek için 40x40x160 mm boyutlarındaki prizmatik numuneler kullanılmıştır. Kendiliğinden yerleşen harçların yayılma çapları Avrupa İnşaat Kimyasalları ve Beton Sistemleri İhtisas Federasyonu standardı referans alınarak belirlenmiştir. Seçilen oranlarda Nevşehir taşı tozu ile oluşturulan numuneler, 23±2 ̊C sıcaklıktaki suya 3 gün süreyle daldırılmıştır. Kür süresi dolan numunelere 3 günün sonunda erken yaş eğilme ve basınç dayanımı testleri uygulanmıştır. Yapılan deneysel analiz sonucunda, en yüksek basınç dayanımlarının, referans numunelerinde ve çimentoyla %5 ikameli Nevşehir taşı tozuyla oluşturulan karışımlarda olduğu belirlenmiştir. Elde edilen sonuçlar, Nevşehir taşı tozunun eğilme dayanımı üzerinde olumlu bir etki sağladığını ancak basınç dayanımında düşüşlere neden olduğunu göstermektedir.

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  AtıfOpenAlex1·TR Dizin1

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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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• MakaleYalnız künye2025Scopus SJRQ1/r/munzur/848
  Dunite powder as a green precursor in one-part alkali-activated composites: Effects on mechanical and durability properties

  Benli, Ahmet; Bayraktar, Oğuzhan Yavuz; Karataş, Mehmet; Bodur, Burak; Yılmazoğlu, Mehmet Uğur; Kaplan, Gökhan

  Natural pozzolans are a sustainable alternative to Portland cement, offering abundant alumina and reactive silica for geopolymer production. Due to their simple extraction methods, they are cost-effective and environmentally friendly. This study explores the utilization of dunite powder (DP) as a sustainable precursor in one-part alkali-activated slag-based composites (AAC), aiming to evaluate its potential to partially replace granulated blast furnace slag (GBFS). The mechanical, fresh, and durability properties of the composites were investigated by varying DP replacement levels (0%, 15%, 30%, and 60%) under an activator dosage of sodium metasilicate, with the mixtures cured at 80 °C for 24 h and subsequently exposed to ambient conditions. The compressive and flexural strengths were evaluated at 7, 28, and 91 days, while the fresh properties (flowability and setting time), durability under sulfate attack, high-temperature resistance, freeze-thaw resistance, dry shrinkage, sorptivity and microstructural characteristics (SEM, XRD, and FT-IR) were also examined. The compressive strength decreased with higher DP content, with the 60% DP mixture showing a 43% strength reduction at 28 days compared to the reference mixture. However, the 30% DP mixture achieved a favorable balance between strength and sustainability, demonstrating a compressive strength decrease of only 11% at 91 days. The mixture containing 15% DP demonstrated the best performance under high-temperature conditions and freeze-thaw cycles. The 60% DP mixture exhibited the highest mass and strength loss when exposed to temperatures above 400 °C and a 15% compressive strength reduction after 120 days of immersion in a 10% MgSO4 solution.

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  AtıfScopus29·OpenAlex22

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• MakaleAçık Erişim2024/r/munzur/5672
  Effect of Ground Diatomite on Early Strength of Self-Compacting Mortars

  Karabulut, Büşra; Yon, Merve Sahin; Karataş, Mehmet

  Portland cement fabrication is a significant factor that increases the amount of carbon dioxide released into nature. For this reason, it is very important to use natural and waste materials with pozzolanic properties instead of portland cement. In this article, the usability of diatomite rock, a natural pozzolanic material that can be substituted with portland cement, in the manufacture of self-compacting mortar was studied. In the experimental study, prismatic specimens with dimensions of 40 × 40 × 160 mm were used to examine the impact of ground diatomite on the early age mechanical properties of self-compacting mortar; it was produced by replacing 0%, 5%, 10%, 15%, 20% of diatomite with portland cement, respectively. The slump-flow test to obtain self-compacting mortar was conducted according to the European Federation of Specialized Construction Chemicals and Concrete Systems guidance. Specimens prepared using 0%, 5%, 10%, 15% and 20% diatomite were cured in water at 23±2 ̊C temperature for 3 days. 3-day (early age) flexural and compressive strength worths were gained for the samples whose curing period was completed. As a result of this experimental study, it was specified that the highest strengths were in the series containing 5% diatomite, exceeding the reference samples. Additionally, it has been determined that mechanical strength decreases when the diatomite ratio in mixtures is more than 5%.

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  AtıfOpenAlex1

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