Browsing by Author "Liban, Roble Ibrahim"

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    Compressive Strength Optimization of Natural Zeolite-Based Geopolymers Via Taguchi Design, Grey Relational Analysis, and Genetic Algorithms
    (IOP Publishing Ltd, 2025) Liban, Roble Ibrahim; Turk, Furkan; Keskin, Ulku Sultan; Yildizel, Sadik Alper
    This study examines the optimization of natural zeolite-based ternary geopolymer mortars via an integrated Taguchi-Grey Relational Analysis-Genetic Algorithm (Taguchi-GRA-GA) framework to improve mechanical performance and durability. Natural zeolite (NZ) was partially substituted (up to 50 wt%) with fly ash (FA) and calcium hydroxide (CH) to enhance binder reactivity and matrix density. A Taguchi L9 orthogonal design was utilized to determine ideal activator values, subsequently employing GRA to amalgamate compressive strength findings at 7, 28, and 90 days into a singular performance index.The top-performing mixtures (F20C20, F25C25, and F30C30) were experimentally validated and utilized to develop regression-based predictive models for subsequent GA optimization. The genetic algorithm identified an optimal formulation (NZ = 214.6 g dm-3, FA = 116.4 g dm-3, CH = 116.4 g dm-3) that achieved a predicted compressive strength of 33.01 MPa, with experimental validation showing a deviation of less than 1.1%. This integrated method demonstrates that the combination of statistical design, data-driven modeling, and evolutionary optimization provides an efficient strategy for developing sustainable, high-performance binders. The resulting materials enhance strength and durability, allowing low-carbon, sustainable construction solutions aligned with global sustainability objectives.
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    Mechanical Strength Variation of Zeolite-Fly Ash Geopolymer Mortars With Different Activator Concentrations
    (Tulpar Academic Publishing, 2021) Liban, Roble Ibrahim; Keskin, Ülkü Sultan; Öztürk, Oğuzhan
    Zeolite is of a significance for geopolymers as it is a natural precursor and does not require additional heat treatment for activation. However, aluminosilicates sourced from natural sources require additional handling for the best use of exploitation. In this study, geopolymers were synthesized by binary use of zeolite and fly ash as main binding material and sodium silicate and sodium hydroxide as alkaline activator. The influence of alkaline activator ratios and sodium hydroxide concentrations on the compressive strength and flexural strength of the zeolite-fly ash based geopolymers were studied. In this research, zeolite-fly ash based geopolymer mortars were produced by using 50% of natural zeolite (clinoptilolite) and 50% of C-type fly ash. Four different activator ratios (Na2SiO3/NaOH: 1, 1.5, 2 and 2.5) and two sodium hydroxide molarities (10M and 12M) was utilized to activate zeolite and fly ash in order to determine the effect of these parameters on the mechanical strengths of the produced geopolymer mortars. The results indicated that as the alkaline activator ratio and NH molarity were increased the compressive strength of the zeolite-fly ash based geopolymers also increased. The maximum compressive and flexural strength values obtained after 28 days of curing were 20.1 MPa and 5.3 MPa respectively and corresponds when used activator ratio of 2.5 and sodium hydroxide concentration of 12 molarity. The obtained results indicated that both the alkaline activator ratio and sodium hydroxide concentration affected the compressive and flexural strengths of zeolite-fly ash based geopolymer mortar specimens. © 2021, Tulpar Academic Publishing. All rights reserved.