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- MakaleYalnız künye2026Scopus SJRQ1Enhancing 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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İncele - MakaleAçık Erişim2024Scopus SJRQ4Experimental Study on Engineering Properties of Recycled Olivine Aggregate Filled CF Reinforced Electrically Conductive Mortars
Dehghanpour, Heydar; Doğan, Fatih; Subaşı, Serkan; Maraşlı, Muhammed
Electrically conductive concretes produced for different purposes were introduced years ago and since then, intensive scientific research has been going on. Studies in the literature have generally been carried out on conventional concretes with electrical conductivity for floor applications. The current study investigates carbon fiber reinforced mortars filled with fine olivine aggregate. Fine aggregate filled mortars are generally produced for building facade applications. Within the scope of the study, the mechanical, electrical, dynamic and microstructural properties of cementitious mortars containing 0.5%, 0.75% and 1.0% carbon fiber and 100% recycled olivine aggregate were investigated. The purpose of performing dynamic resonance tests was to investigate the effect of carbon fiber on damping ratio. 28-Day compressive, flexural, dynamic resonance, ultrasonic pulse velocity (UPV), Leeb hardness and dry density tests of conductive mortar samples obtained from four different mixtures were performed. In addition, 2, 14, 28, 90 and 180 days electrical conductivity tests were carried out to determine their resistivity in different time intervals. The purpose of performing dynamic resonance tests was to investigate the effect of carbon fiber on damping ratio. While a significant positive effect of CF on electrical conductivity and damping ratio was observed, a negligible decrease in mechanical results was observed. Calcium silicate hydrate (C-S-H) structure formed by hydration using olivine filler in the cement mixture confirmed the binding formations.
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İncele - MakaleYalnız künye2023Scopus SJRQ2Effect of impactor nose form on the impact behavior of reinforced composite materials
Dogan, Sonay; Arman, Yusuf; Dogan, Akar
The goal of the present study is to investigate the influence of impactor shape on the low-velocity impact behavior of the composite panels manufactured with different reinforcement materials at the same thicknesses, experimentally. Kevlar, carbon, S-2 glass woven fabric and epoxy matrix have been used to manufacture thermoset composites with the vacuum-assisted resin infusion molding method. The Fractovis plus test machine with a 12.7 mm diameter hemispherical and two different conical impactor noses was used to perform impact tests. The effects of impactor shapes on the low-velocity impact behavior have been compared for 20 J, 40 J, and 60 J energy levels. Although at the same impact energy level, S-2 glass fiber-reinforced epoxy specimens have a higher perforation threshold than carbon and Kevlar fiber-reinforced epoxy. Because to achieve the same thickness, the number of S-2 glass layers was greater than the number of carbon and Kevlar layers. Additionally, the form of the impactor greatly influenced the perforation threshold.
AtıfScopus7WoS7OpenAlex6İncele - MakaleAçık Erişim2022Characterization of carbon fiber reinforced conductive mortars filled with recycled ferrochrome slag aggregates
Doğan, Fatih; Dehghanpour, Heydar; Subaşi, Serkan; Maraşli, Muhammed
Recently, it has been known that carbon fiber, a conductive fiber, is used in different mixture designs and the development of electrically conductive cementitious materials. Howev-er, the evaluation of ferrochrome slag as a recycled aggregate in the mixture of these special concretes has still not been investigated. In this study, electrically conductive mortars were produced using 100% recycled ferrochrome slag aggregate with a particle size of less than 1 mm as filling material and using carbon fiber in 4 different ratios, 0%, 0.5%, 0.75%, and 1%. To investigate the electrical conductivity properties, the resistivity values of the samples were measured at five different times within 2–180 days. In addition, 28-day compressive strength, flexural strength, dynamic resonance, ultrasonic pulse velocity, Leeb hardness, scanning elec-tron microscope, and X-Ray Diffraction tests were performed on all samples. The results were compared with the literature, proving that ferrochrome slag could be used as a reasonable aggregate in conductive mortars. The age effect was minimal in CF-added mixtures. With the addition of 1% CF, the resistivity values decreased approximately 40 times compared to the ref-erence. Moreover, SEM analyses of the CF-0.75 sample showed that the CFs adhered to form a conductive network between the components in the ferrochrome-filled compact structure.
AtıfScopus10TR Dizin5İncele - MakaleYalnız künye2021Scopus SJRQ1Low-velocity impact, bending, and compression response of carbon fiber/epoxy-based sandwich composites with different types of core materials
Dogan, Akar
This study focuses on the investigation of the effects of different core types on the low velocity impact, three-point bending and out-of-plane compression loading performance of sandwich composites. Three core materials were selected: Balsa wood, PVC foam, and Ayous wood. The facesheets of sandwich composites were produced by woven carbon/epoxy. Balsa and PVC foam are widely used in sandwich composites as core materials. In this study, Ayous wood, which is the lightest tree after Balsa, was used as core material in addition to traditional core materials. Woven carbon fiber fabrics with an areal density 200 g/m2 as reinforcement and epoxy matrix were used to produce the sandwich composite. Vacuum-assisted resin infusion molding method was used to manufacture composite panels. A number of tests under various impact energy levels for three different sandwich composites were conducted with Fractovis Plus impact testing machine in order to investigate the energy absorption capacity of sandwich composites. Maximum contact forces, absorbed energies, and the maximum deflections of sandwich panels were obtained for each impact energy level. Despite having the same facesheets, Ayous core sandwich composites possess a higher perforation threshold than Balsa and PVC foam sandwich composites. The perforation threshold of Balsa, PVC foam, and Ayous sandwich composites are 85, 72, and 170 J, respectively. In addition, the Ayous core sandwich composites have better bending and compression strengths. The bending strength of the Ayous sandwich composite is higher about six times than PVC sandwich composite and about two times than Balsa sandwich composite.
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