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Öğe 3D electrothermal analysis of electrically conductive concrete slabs: Finite element method(Techno-Press, 2025) Dehghanpour, Heydar; Marasli, Muhammed; Subasi, Serkan; Ozdal, VolkanThe investigation of electrically conductive concrete as a new generation building material has gathered great attention from researchers. The broadest aspect of the produc-tion and research purposes of conductive concrete is heatable slabs. However, experi-mental electrothermal tests of this type of building materials are costly in terms of la-bor and production and involve time-consuming processes. In this study, electrother-mal analyzes were carried out using the Abaqus program to investigate the effect of the cross-sectional geometry between the electrodes on the thermal performance. The aim was to estimate a suitable cross-section geometry with low cost and time. In the analysis, applicable sections with 6 different geometries and a width of one meter were preferred. Concrete properties were obtained from the author's previous experimental studies. A potential difference of 24 V was defined in all models throughout the simu-lation period. According to the electrothermal analysis results, the increase in total volume caused the resulting temperature and heat energy to increase. The analysis demonstrated that optimizing the cross-sectional area of the models led to improved temperature distribution and heat energy efficiency while achieving significant concrete volume savings, highlighting the potential for more sustainable design approaches.Öğe A novel lanthanum hexaboride-modified cementitious composites: evolution and microstructural architecture of LaB6-integrated GFRC systems with enhanced dielectric response(Elsevier Science Sa, 2026) Demir, Ahmet; Subasi, Serkan; Dehgan, Haydar; Ramazanoglu, Dogu; Marasli, Muhammed; Aksu, Mecit; Subasi, AzimeThis study investigates the integration of lanthanum hexaboride (LaB6) microparticles into glass fiber-reinforced concrete (GFRC) to improve its dielectric and microstructural properties. GFRC mixtures with 1-3 % LaB6 replacement were characterized for capacitance, impedance, dielectric constant (epsilon ' and epsilon ''), dissipation factor (tan delta), electrical modulus (M ' and M ''), and Cole-Cole diagrams across varying frequencies (20 Hz-5 MHz) and hydration times (7-58 days). Comprehensive Microstructural, Thermal Stability, and Chemical Characterization analyses were also performed. Results demonstrate that LaB6 significantly improves GFRC's capacitance, conductivity, and dielectric properties. Specifically, L2 and L3 samples exhibited capacitance values approximately 100 times higher than the reference and L1 samples after 56 days, and approximately 25 times greater capacitance behavior across the tested frequency spectrum. The real dielectric constant (epsilon ') reached 250-fold, decreasing by about 10 times with LaB6 addition in L2 and L3, indicating improved insulation. Dielectric losses (epsilon '') were also markedly higher for L2 and L3, approaching 100 times greater than R and L1, implying favorable conductive functionality. Cole-Cole analysis indicated minimal dielectric dispersion for L2 and L3, suggesting near-ideal polarizable interfaces. Equivalent circuits were fitted, demonstrating that LaB6 significantly influences the electrical transport and storage mechanisms within the GFRC composites, leading to improved dielectric performance. Scanning electron microscopy (SEM) revealed denser microstructures, while thermogravimetric analysis (TGA), differential thermal analysis (DTA), and Fourier-transform infrared spectroscopy (FTIR) corroborated enhanced thermal stability, bond strength, and favorable microstructural interactions. These findings highlight LaB6 as a promising additive for developing high-performance cementitious composites with tailored electrical responses for smart concrete applications.Öğe Corrosion of Centrifuged Hot Dip Galvanized Pad Hooks Used in GFRC Panels(Pleiades Publishing Ltd, 2024) Gerengi, Husnu; Marasli, Muhammed; Solomon, Moses M.; Coskun, Kader; Guner, YusufAnchor elements and pad hooks are necessary components for securing GFRC panels to the main building structure, but they are vulnerable to corrosion when exposed to the atmosphere. This study evaluated the corrosion resistance of two centrifuged hot-dip pad hooks (designated A1 and B1) in a 5% (w/v) NaCl solution. The samples were subjected to a 20-day salt spray test and observed visually and through SEM-EDX for elemental composition. The thickness of the surface coating was measured before and after the salt spray test. The visual observation and SEM images indicate that the pad hook samples remained corrosion-free in the studied environment as the brownish iron oxides were not observed. The surface products were mainly Zn-rich corrosion products. The average thickness of samples A1 and B1 before the corrosion test was found to be 78.15 and 145.65 mu m. After the corrosion test, the thickness increased to 100.98 and 191.74 mu m for samples A1 and B1, respectively. The EDX results, however, revealed that both samples were corroded when exposed to the corrosive medium but B1 had a superior resistance than A1. It is therefore recommended to improve the production processes to focus on surface pre-treatment and Zn coating thickness for improved corrosion resistance.Öğe Cyclic behavior of autoclaved aerated concrete block infill walls strengthened by basalt and glass fiber composites(Elsevier Sci Ltd, 2021) Arslan, Mehmet Emin; Aykanat, Batuhan; Subasi, Serkan; Marasli, MuhammedIn this study, the effects of 10 mm bilaterally applied basalt and glass fiber reinforced (BRC and GRC) cementitious plasters with different fiber content (1.0%, 2.0% and 3.0%) on the behavior of the autoclaved aerated concrete (AAC) block infill walls were investigated. For this purpose, 8 infill walls with dimensions of 150 x 150 x 20 cm were produced to examine the behavior of the infill walls under reversed cyclic loading. The load carrying capacities, stiffness degradation and energy dissipation capacities of the infill walls placed in a steel frame with hinges on all four corners were determined by using hysteretic load-displacement curves to evaluate effects of fiber reinforced cementitious plaster. The test results show that BRC and GRC plaster applications considerably increase the load carrying and energy dissipation capacities of the infill walls. However, the experimental results illustrated that the usage of BRC plasters in strengthening of the AAC block infill walls needs more attention. Having similar results for different fiber ratios in the use of GRC reveals that it may be more rational to use 1.0% fiber content for the most economical solution for strengthening. Although the results obtained in this study are valid for infill walls, the experimental results show that GRC plasters can also be used in strengthening of masonry walls. It is recommended that this method can be used quickly and effectively in strengthening of masonry structures, which occupy an important place in the existing building stock.Öğe The effect of crude and calcined sepiolite on some physical and mechanical properties of glass fiber reinforced concrete(Serban Solacolu Foundation, 2023) Saka, Rasim Cem; Subasi, Serka; Marasli, MuhammedThe technical term GRC (glass fiber reinforced concrete) is widely used in the precast industry. This type of concrete, which is obtained by mixing cement, sand, glass fibers and some chemicals, is very durable. Compared to conventional concretes, high compressive, flexural and impact strength is the preferred choice for building facade coatings. In this paper, the usability of sepiolite as a pozzolan in glass fiber reinforced concrete and its effects on mechanical and physical properties were investigated. GRC samples were produced by adding 3% glass fiber by volume to substituted mixtures. Crude and calcined sepiolites were replaced with cement at 5%, 10%, 15% and 20% by weight. Compressive strength, flexural strength, impact strength and abrasion resistance of produced GRC samples were determined. As a result, It was observed that as sepiolite ratio increased, mechanical and physical properties of samples decreased in early and later ages, and crude sepiolite substituted samples had lower mechanical strength than the calcined sepiolite substituted samples.Öğe Electrical and dielectric tailoring of glass fiber-reinforced concrete using ZnO-based hybrid nanocomposites(Springer, 2026) Ramazanoglu, Dogu; Musatat, Ahmad Badreddin; Subasi, Azime; Demir, Ahmet; Subasi, Serkan; Marasli, MuhammedThis study investigates frequency-dependent dielectric and electrical transport properties of glass fiber-reinforced concrete (GFRC) systematically doped with ZnO-based hybrid composite (ZnO-@) nanoparticles at 1%, 2%, and 3% mass fractions. Electrical impedance spectroscopy (20 Hz-5 MHz) coupled with microstructural characterization (SEM-EDX, FTIR) and mechanical validation establishes concentration-dependent polarization mechanisms governing electromagnetic property modulation. The 2% ZnO-@ formulation exhibits optimal dielectric enhancement with maximum real permittivity (epsilon '), superior AC conductivity (100 Hz-10 kHz domain), and 100% imaginary modulus augmentation (M ''), attributed to Maxwell-Wagner-Sillars interfacial polarization at ZnO-cement matrix boundaries. Equivalent circuit modeling reveals that grain boundary resistance escalates to 5.8 M Omega at optimal doping, and constant phase element (CPE) exponent values (P = 0.77-0.84) confirming non-Debye relaxation due to hierarchical microstructural heterogeneity. The critical percolation threshold, between 2% and 3% ZnO concentration, demarcates the transition from capacitive to conductive behavior, where specimens at 3% exhibit dielectric parameter regression toward baseline values due to nanoparticle agglomeration and the formation of conductive pathways. Spectroscopic validation confirms the integration of wurtzite-phase ZnO (Zn-O: 474 cm(-)1) with preserved calcium silicate hydrate phases, while post-aging Leeb hardness measurements demonstrate 171-176% mechanical reinforcement (387-456 HLD), validating the retention of structural durability. These findings establish quantitative compositional guidelines for engineering multifunctional construction composites with tailored electromagnetic response characteristics for interference shielding, capacitive energy storage, and electromagnetically compatible innovative infrastructure applications.Öğe Hydrothermally Synthesized Chitosan-SnO2-CuO Nanohybrids for Antimicrobial Surface Engineering of GFRC(Springer, 2026) Ramazanoglu, Dogu; Duran, Pelin Kamuran; Sahin, Idris; Subasi, Serkan; Marasli, MuhammedGlass fiber reinforced concrete (GFRC) panels are widely used in architectural and structural applications due to their low weight and design flexibility, but their hydrophilic and porous surfaces are prone to microbial colonization, compromising durability and aesthetics. In this study, GFRC surfaces were functionalized with hydrothermally synthesized chitosan-SnO2-CuO nanohybrids to enhance their physicochemical and antimicrobial properties. Structural and morphological analyses (XRD, SEM, FTIR, BET) confirmed successful nanohybrid incorporation, revealing increased surface area (3.40 to 15.77 m & sup2;/g) and modified chemical bonding. Water contact angle measurements indicated improved hydrophobicity (30.82 degrees to 63.49 degrees), while TGA/DTA showed enhanced thermal stability (final residue 16.9% to 18.07% at 800 degrees C). The nanohybrid coatings exhibited significant antimicrobial activity against E. coli, S. aureus, C. albicans, and T. tonsurans, with inhibition zones up to 36 mm and 29 mm at 2-3% additive concentrations. Thermal conductivity increased from 2.44 to 2.82 W/mK, demonstrating multifunctionality. These results highlight the potential of Ch-SnO2-CuO nanohybrid coatings as a robust, multifunctional strategy for producing antimicrobial, thermally stable GFRC surfaces suitable for hygiene-critical environments.Öğe Innovative Surface Improvement of GFRC Using Hydrothermally Produced Ch-TiO2-CuO Nanohybrid Composite Additives(Elsevier Sci Ltd, 2024) Ramazanoglu, Dogu; Subasi, Serkan; Marasli, MuhammedThis study examines the impact of the Ch-TiO2-CuO nanohybrid composite on the surface properties and antimicrobial effects of Glass fiber-reinforced concrete (GFRC) panels. GFRC panels are known for their durability and aesthetic compatibility, making them suitable for exterior facades and historic restoration work. However, their porosity and hydrophilic nature make them susceptible to microbial colonization, affecting their durability and visual appeal. To address this, antimicrobial nanohybrid crystals (Ch-TiO2-CuO) were developed using a hydrothermal method and incorporated into GFRC panels. This integration offers significant advantages, including reduced maintenance, long-term structural integrity, and preserved aesthetic properties. Additionally, this approach aligns with sustainability goals by enhancing the environmental friendliness of GFRC over its lifetime. The study concludes that incorporating antimicrobial agents into GFRC production supports smart city initiatives by providing long-term protection against microbial degradation while maintaining aesthetic standards, thus contributing to cleaner, safer urban environments.Öğe Microencapsulated phase change material incorporated light transmitting gypsum composite for thermal energy saving in buildings(Elsevier, 2023) Gencel, Osman; Bayram, Muhammed; Subasi, Serkan; Hekimoglu, Gokhan; Sari, Ahmet; Ustaoglu, Abid; Marasli, MuhammedThe increased energy consumption for specific applications, including heating, cooling, air conditioning and lighting of residential and commercial buildings accelerate the research efforts concentrated on developing thermal energy storage capacity of buildings materials in recent years. Likewise, the development of light-transmitting building elements is a novel energy-saving technique that enhances lighting efficiency in build-ings. In light of these, the current study seeks to design an untried microencapsulated phase change material (MPCM) integrated glass fiber reinforced gypsum composite with sufficient light-transmitting properties and thermal energy storage capacity. In this research, a multi-scale investigation of light-transmitting gypsum composite was conducted experimentally with physical, mechanical, chemical, microstructural, thermal, light transmittance and solar thermoregulation tests. The gypsum composite is formed from alpha-gypsum, water, polymer admixture, alkali-resistant glass fiber (AR-GF), several concentrations of MPCM, and plastic optical grids to allow light to transmit through the board. Although higher fractions of MPCM yielded an apparent decrease in me-chanical strength test results, 5 wt% introduction of MPCM to the reference matrix reduced the compressive and flexural strength of specimens by 1 and 8 %, respectively. The results verified a reduction trend in thermal conductivity of composites with MPCM loading. DSC investigations revealed that the melting temperature and the regarding latent heat storage capacity of gypsum composite with 15 wt% of MCPM are 17.76 degrees C and 19.2 J/g, respectively. Light-transmitting gypsum composites showed up to similar to 10 % light transmittance, that can greatly increase the efficiency of lighting in buildings. The produced gypsum composites with MPCM kept the test room cooler during the highest temperature, while it provided a warmer room during the nighttime for an extended time. The study's findings are applicable to increase thermal comfort by reducing the significant temperature variations in buildings and improving artificial lighting efficiency, encouraging the design of sustainable building applications.Öğe Multifunctional GFRC composites: PEDOT: PSS-driven dielectric enhancement for energy storage and sensing applications(Elsevier Science Sa, 2026) Demir, Ahmet; Musatat, Ahmad Badreddin; Subasi, Azime; Ramazanoglu, Dogu; Dehgan, Haydar; Marasli, Muhammed; Gencel, OsmanThis study presents a comprehensive investigation into the development and characterization of multifunctional Glass Fiber Reinforced Cement (GFRC) composites enhanced with Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT: PSS) to impart advanced electrical properties. We systematically analyzed the influence of PEDOT: PSS concentration (0-15 wt %) and curing age on the dielectric behavior of these novel composites, evaluating their capacitance, dielectric constant, loss factor, and electrical modulus across a broad frequency range (10 Hz-10 MHz). The integration of PEDOT: PSS significantly modified the material's electrical characteristics, demonstrating concentration-dependent variations and complex relaxation mechanisms dominated by Maxwell-Wagner interfacial polarization. The optimized P2 formulation (10 wt % PEDOT: PSS) exhibited superior electrochemical performance, maintaining the highest capacitance values and achieving a peak dissipation factor (tan delta) of 0.43 +/- 0.02 at day 15, representing a 185 % enhancement over unmodified GFRC. EDX analysis confirmed successful polymer incorporation, with P2 exhibiting the highest carbon content (5.8 wt %) and sulfur content (1.8 wt %), indicating optimal dispersion. Equivalent circuit models were established and validated (R2 > 0.98), providing insights into complex charge transport mechanisms within this hybrid material. Microstructural analyses via scanning electron microscopy revealed significant morphological modifications, including the formation of crystalline and plate-like structures, while complementary FT-IR and TGA analyses confirmed polymer-cement interaction stability and thermal stability up to 450 degrees C. These findings establish fundamental design principles for creating electrically conductive cementitious materials with tunable dielectric properties, enabling strategic deployment in innovative infrastructure systems, energy storage devices, and electromagnetic shielding technologies.Öğe Production and assessment of UV-cured resin coated stearyl alcohol/ expanded graphite as novel shape-stable composite phase change material for thermal energy storage(Pergamon-Elsevier Science Ltd, 2024) Guler, Onur; Er, Yusuf; Hekimoglu, Gokhan; Ustaoglu, Abid; Sari, Ahmet; Subasi, Serkan; Marasli, MuhammedExpanded graphite -phase change materials (PCM) structures are reinforced to polymers with various methods to fabricate advanced thermal energy storage materials. However, these methods still suffer from processing time and product efficiency challenges. In this study, the UV-curing method was used to produce shape-stable EGPCM-reinforced resin composites with fast curing and low process temperature of the resin. The composite material, comprising UV -curable resin (30 %), stearyl alcohol (65 %), and Expanded graphite (5 %), was synthesized. This synthesis aimed to address the limitations of traditional PCMs, such as low thermal conductivity and leakage. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to characterize the materials ' phase change behavior and thermal stability. Scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) analyses were conducted to elucidate the microstructure and crystallinity of composite materials. The composites, exhibiting near-perfect impermeability with leakage as minimal as 0.89 %, not only enable the attainment of cooler environments by 2 - 3 degrees C under hot air conditions but also demonstrate exceptional thermal stability up to 207 degrees C, as evidenced by TGA results. Additionally, they offer a remarkable melting enthalpy value of 153.1 J/g. These composites, with their shape-retention ability during phase transitions and high thermal energy storage capacity, are a versatile and efficient option for sustainable energy management. This research contributes to the development of innovative materials for renewable energy integration and reducing carbon emissions.Öğe Replacing natural aggregates with phase change material-based 3D printed aggregates in concrete for structural function and dual thermal energy storage(Elsevier, 2026) Gencel, Osman; Er, Yusuf; Guler, Onur; Ustaoglu, Abid; Sari, Ahmet; Subasi, Serkan; Marasli, MuhammedExtraction of natural aggregates for concrete not only depletes non-renewable resources but also causes habitat loss, groundwater disruption, and carbon emissions. At the same time, sustainable and energy-efficient construction demands materials capable of reducing operational energy. Integrating phase change materials (PCMs) into cementitious systems is promising for passive thermal regulation, yet conventional methods (microencapsulation, coatings) suffer from leakage, poor dispersion, and weak bonding. This study proposes replacing natural stone with 3D-printed smart aggregates embedding 50 wt% methyl palmitate (MP), combining structural compatibility with latent-heat storage. Concretes with natural aggregates (NA), synthetic aggregates (AA), and PCM-integrated aggregates (AAPCM) were compared in this study. At 28 days, compressive strength dropped from 92.99 MPa (NA) to 58.39 MPa (AA) and 44.34 MPa (AAPCM); ultrasonic pulse velocity decreased from 4.49 to 4.26 to 3.91 km/s. Thermal conductivity reduced by similar to 52% (1.26 -> 0.606 W/mK). DSC confirmed latent-heat storage of 224 J/g (MP) and 109 J/g (AAPCM) with >99% retention after 500 cycles. Outdoor tests showed up to 5 degrees C surface cooling and delayed heat release near 26 degrees C. Thus, PCM-integrated aggregates mitigate the environmental burden of quarrying while delivering thermally adaptive concretes, suitable for fa & ccedil;ades, pavements, and energy-resilient building envelopes.
