Scopus İndeksli Yayınlar Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/395

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Publisher: search.filters.publisher.ElsevierSubject: search.filters.subject.Geopolymer Concrete

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  • Article
    Citation - WoS: 2
    Citation - Scopus: 2
    Experimental and Numerical Analysis of Damage and Crack Behavior in Geopolymer and Ordinary Portland Cement Reinforced Concrete Columns
    (Elsevier, 2025-10) Ozbayrak, Ahmet; Kucukgoncu, Hurmet; Aslanbay, Yuksel Gul; Aslanbay, Huseyin Hilmi
    This study evaluates and compares the structural behavior of reinforced concrete columns produced with geopolymer concrete (GPC) and ordinary Portland cement (OPC) under eccentric axial loading, aiming to investigate GPC's potential as a sustainable alternative. A total of twenty columns with varying longitudinal reinforcement ratios, curing methods, eccentricities, and geopolymer formulations were experimentally tested. Displacement measurements at each load increment were obtained using a total station, allowing crack pattern tracking at key stages such as first cracking, yielding, and ultimate failure. These observations were schematically documented using AutoCAD. Additionally, finite element models were developed in ABAQUS using the Concrete Damage Plasticity (CDP) model, with material parameters calibrated based on experimental compressive and tensile strengths, elastic modulus, and fracture energy. Results indicated that increasing eccentricity reduces axial load capacity while increasing lateral deformation. While the reinforcement ratio did not significantly affect axial strength, it increased displacement demand. Due to their distinct microstructural characteristics, GPC columns exhibited greater deformation capacity and narrower, more localized crack patterns than OPC columns. Furthermore, the sodium silicate/sodium hydroxide (SS/SH) ratio and curing duration significantly influenced the structural response of GPC. Numerical simulations showed strong agreement with experimental results regarding load-displacement behavior and damage distribution. These findings demonstrate that GPC can serve as a reliable and sustainable alternative to OPC in structural column applications, provided its specific material properties are considered in design and analysis.
  • Article
    Citation - WoS: 53
    Citation - Scopus: 55
    Comprehensive Experimental Analysis of the Effects of Elevated Temperatures in Geopolymer Concretes With Variable Alkali Activator Ratios
    (Elsevier, 2023) Ozbayrak, Ahmet; Kucukgoncu, Hurmet; Aslanbay, Huseyin Hilmi; Aslanbay, Yuksel Gul; Atas, Oguzhan
    By growing population and rapid urbanization, demand for concrete increases exponentially. Researches on use of fly ash material in waste product class for concrete production are important to produce concrete more environmentally friendly. However, there is a need for more research to use geopolymer concrete (GPC) in every field where ordinary Portland cement concrete (OPC) is used. Therefore, it is crucial to experimentally investigate thermal properties as well as me-chanical properties of geopolymer concrete. As investigated thermal properties, the main factor affecting strength development of GPC is alkali activator ratios. In this study, GPC prism samples with nine different compositions, produced by various alkali ratios. After flexural strength tests, they were cut into cubes and exposed to 400 degrees C, 600 degrees C and 800 degrees C, then they were subjected to compressive strength tests. Results obtained from different AA/FA and SS/SH ratios were eval-uated as mechanical properties at ambient temperature and physical, mechanical and micro-structural properties at elevated temperature. An empirical formula, which considers the effect of activator ratios, was proposed to calculate flexural strength depending on compressive strength of samples at ambient temperature. As an increase of SS/SH and AA/FA ratios, compressive strength increased, while flexural strength decreased. The increase in AA/FA ratio decreased compressive strength of samples exposed to high temperatures, while increase in SS/SH ratio did not deter-mine at elevated temperatures. There is an inverse change with AA/FA ratio and parallel change with SS/SH ratio between compressive strengths of samples at ambient temperature and exposed to high temperature.