WoS İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/394
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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: 46Citation - Scopus: 52Life Cycle Assessment of Lightweight Concrete Containing Recycled Plastics and Fly Ash(Taylor & Francis Ltd, 2020-06-05) Ersan, Yusuf Cagatay; Gulcimen, Sedat; Imis, Tuba Nur; Saygin, Osman; Uzal, NigmetResearchers put significant effort to decrease the environmental impact of concrete by using industrial by-products as an alternative binder. However, the considerable environmental impact still exists due to the consumption of natural resources as aggregates. Natural aggregates are the most used resources by volume in the construction sector. Therefore, it is necessary to investigate by-products as an alternative to natural aggregates as well. This study presents the environmental impact of lightweight concrete (LWC) produced by replacing natural aggregates with recycled waste plastic (polyethylene) (RWP) and partially replacing Portland cement with Class F fly ash (FA). Life Cycle Assessment (LCA) was performed to compare a conventional LWC, containing pumice as natural aggregate and Portland cement as a binder, with green LWC, containing 30% RWP as pumice replacement and 20% FA as cement replacement. These scenarios were evaluated in terms of global warming potential, abiotic depletion, ozone layer depletion, terrestrial ecotoxicity, photochemical oxidation, acidification and eutrophication. LCA was coupled with mechanical tests at 7 days and 28 days. RWPs were found to be an environment-friendly replacement material for natural lightweight aggregates with an overall decrease in all CML-IA impacts except eutrophication. Tested green mix design also provided sufficient strength for nonstructural applications.Article Citation - WoS: 76Citation - Scopus: 81Influence of NaNo SiO2 and NaNo CaCo3 Particles on Strength, Workability, and Microstructural Properties of Fly Ash-Based Geopolymer(Ernst & Sohn, 2020-05-06) Durak, Ugur; Karahan, Okan; Uzal, Burak; Ilkentapar, Serhan; Atis, Cengiz DuranThe influence of nano SiO2(NS) and CaCO3(NC) particles on the properties of class F fly ash based geopolymer mortar activated with different sodium ion concentrations have been investigated. Mortar mixture proportions were 1:3:0.3 for binder, sand, and water, respectively. Nano SiO2 and CaCO3 particles were replaced with a binder by weight basis at the ratios of 1, 2, and 3% in the mixtures. Sodium concentrations amount used were 8, 10, and 12% Na+ of binder content. Geopolymer mortar samples were cured at 60, 75, and 90 degrees C in a furnace for 24, 48, and 72 hr. After the heat curing process, flexural, and compressive strength tests were performed. The changes in the microstructure of geopolymer due to influence of nanoparticles were examined by utilizing isothermal calorimetric studies on geopolymer paste, and field-emission scanning electron microscopy (FESEM). Based on laboratory work results, it was concluded that for all sodium ion concentrations, the addition of nano SiO2 and CaCO3 particles improved the flexural and compressive strengths after 24 hr heat curing. However, the favorable effects of nanoparticles on strength properties tend to disappear after 48 and 72 hr heat curing. The results of isothermal calorimetric studies showed that nano SiO2 and CaCO3 particles accelerated the geopolymeric reactions at an early age. FESEM results showed that additions of nanoparticles made the microstructure of geopolymer products more intense and compact.