WoS İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/394
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Article Production of Waste-Based Lightweight Geopolymer Concretes Using Calcined Bentonite, Fly Ash, Slag, and Expanded Polystyrene Granules(Taylor & Francis Inc, 2026-03-19) Top, Soner; Nussrat Shukur Shukur, Yasir; Vapur, HüseyinThis study investigates the production of environmentally friendly lightweight geopolymer concretes utilizing fly ash (FA) as the primary precursor with calcined calcium bentonite (CCB), ferrochrome slag (SG), and expanded polystyrene (EPS) as supplementary components. A Box-Behnken design was employed to investigate the combined effects of CCB and SG additions, along with the solid-to-liquid ratio, on the compressive strength. Moderate CCB incorporation, particularly around 10%, improved mechanical performance, achieving strengths above 48 MPa, with a maximum of 51.33 MPa at 90 degrees C for a mix containing 5% CCB and 5% SG. Higher CCB dosages (>20%) reduced strength due to matrix dilution, while SG showed limited contribution at elevated levels. Incorporation of EPS granules reduced density to as low as 1292 kg/m & sup3;, yet compressive strengths between 25 and 30 MPa were maintained in mixes with 10% CCB and 0.3% EPS. SEM-EDX analysis confirmed dense geopolymer matrices in FA-CCB composites, whereas SG particles appeared less integrated. These results confirm the potential for producing high-strength, lightweight geopolymer concretes through the effective valorization of waste. The combined use of FA, CCB, SG, and EPS offers a sustainable pathway for resource-efficient construction that supports circular resource utilization.Article Sustainable Stabilization of Peat Soil with Hybrid Geopolymer Jet Grout Columns(Springer Int Publ A.G., 2025-10-15) Yalcin, Hakan; Erol, Aykut; Kaya, Zulkuf; Cadir, Cenk Cuma; Uncuoglu, Erdal; Akin, Muge K.Peat soils present severe challenges in geotechnical engineering due to their low shear strength, high water content, and aggressive chemical environments such as sulfate exposure. While cement-based jet grouting (JG) is widely used, it entails high carbon emissions and energy consumption. Hybrid geopolymer jet grout columns (HGJGCs) are presented in this work as a viable and sustainable alternative. Unlike conventional geopolymer studies that rely on pre-cured molds later exposed to aggressive environments, this research simulates realistic field conditions by injecting fresh geopolymer directly into sulfate-rich peat, where early-age durability and strength are critical. To address early strength limitations commonly seen in aggressive situations, a tiny amount of cement was added to the fly ash/GGBFS-based combination. Crucially, there is no need for high heat because the mechanism cures at room temperature. Physical model testing, laboratory-scale jet grouting, and performance comparisons with conventional JGCs were all carried out. Results show that HGJGCs increased the bearing capacity of peat by 5.5 times, improved compressive strength (5.3-5.7 MPa), and reduced settlement more effectively than JGCs. Additionally, CO2 emissions were reduced by 25.14% due to lower binder-related emissions and energy demand. This work shows that hybrid geopolymer systems are a viable, low-carbon substitute for peat stabilization because they can function well in real-world, chemically demanding situations.Article Citation - WoS: 35Citation - Scopus: 29Microstructural Analysis of Low-Calcium Fly Ash-Based Geopolymer Concrete With Different Ratios of Activator and Binder Under High Temperatures(Springer Heidelberg, 2024-06-25) Kucukgoncu, Hurmet; Ozbayrak, AhmetGeopolymer concretes have emerged as an alternative to traditional Portland cement concretes with high strength, good durability, well corrosion performance and high-temperature resistance, and being a sustainable and environmentally friendly material. In this study, a comprehensive microstructural analysis of low-calcium fly ash-based geopolymer concrete samples with different alkali activator to binder ratios was conducted after exposure to temperatures ranging from 400 to 800 degrees C. The experimental results of the geopolymer concrete specimens found out significant findings, including a notable loss of mass and an approximate 80% decrease in compressive strength after exposure to 800 degrees C. The microstructural analysis underlined crack formation, voids and porosities in the geopolymer matrix at elevated temperatures, affecting the physical and mechanical properties of the material. The study presents significant insights into the behaviour of low-calcium fly ash-based geopolymer concrete with different binder and alkali activator ratios under high temperatures, revealing the performance of geopolymer concretes in extreme environments and the effect of incompatibility between geopolymer concrete and aggregate due to thermal temperature effects on this performance.