Scopus İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/395
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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.Article Citation - WoS: 3Citation - Scopus: 3Equivalent Stress Block Parameters for Fly Ash-Based Geopolymer Concrete Structural Elements(Ernst & Sohn, 2025-03-06) Ozbayrak, Ahmet; Kucukgoncu, HurmetResearch on the design of structural members made from geopolymer concrete (GPC) remains limited. This study investigates the applicability of equivalent rectangular stress block parameters, traditionally used for reinforced concrete design, in GPC structural elements. We conducted experimental tests on 20 columns (16 GPC, 4 Ordinary Portland Cement [OPC]) and 15 beams (12 GPC, 3 OPC) produced using fly ash-based GPC and standard OPC. These tests involved subjecting the specimens to various loading conditions to measure their ultimate compressive strength and strain. The findings demonstrate that these factors significantly influence the stress block parameters in GPC samples. Notably, parameters k(1) and k(3) were compatible with ACI 318 and Eurocode 2 standards, with deviations within acceptable limits, supporting GPC's potential for use in conventional reinforced concrete frameworks. The study also reveals that GPC columns and beams have higher balanced reinforcement ratios than OPC, due to GPC's increased deformation capacity and strain values. According to the results, the average balanced reinforcement ratio of GPC column specimens is 30% higher than that of OPC, while that of GPC beam specimens is 6% higher. Variations in alkaline activation and curing methods did not significantly impact the equivalent stress block parameters. The change between the average equivalent stress block parameters obtained from GPC and OPC beam samples varies between 1% and 5%, while the change in column samples is around 1%. Although the longitudinal reinforcement ratios in the tests are variable, the averages of the calculated equivalent stress block parameters are close. The experimental results align with numerical analysis, emphasizing GPC's suitability as an alternative material in structural applications. These findings provide a basis for incorporating GPC into existing design standards, with adjustments for its distinct mechanical behavior.