Sürdürülebilir Kalkınma Amaçları

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• MakaleYalnız künye2021Scopus SJRQ1/r/bayburt/14078
  Enhancing Burnability Characteristics of Low-Temperature Burnt-Cement Clinker by Recycling Phosphogypsum Wastes

  Aksan, U.; Köseoglu, K.; Gökçe, H. S.

  In the present study, the effect of phosphogypsum, a byproduct from the phosphoric acid production industry, on the clinkerization process was researched in order to improve the burnability of clinkers at lower burning temperatures. Raw meal samples containing phosphogypsum at 0%, 1%, 3%, and 5% by weight were burned at 1,350 degrees C, 1,400 degrees C, 1,450 degrees C, and 1,500 degrees C. The introduction of phosphogypsum reduced the presence of unbounded (free) CaO relatively up to 43%. Thus, the mineralization effect of phosphogypsum promotes lower burning temperatures. The free CaO content of the 5% phosphogypsum containing clinker decreased to 0.94% at 1,400 degrees C after 120 min of burning time. The free CaO content was found to be almost identical (0.75%) to that of industrial clinker burned in a rotary kiln at 1,500 degrees C. Due to the low free CaO content (<1%) and the burnability index (73), the recycling of phosphogypsum wastes was found to be suitable for the production of eco-efficient clinkers. The reduced energy consumption and energy-related CO2 emissions in such modified clinkers can contribute to the economic and ecological goals of the cement industry. (C) 2021 American Society of Civil Engineers.

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  AtıfWoS2·OpenAlex3

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• MakaleAçık Erişim2020Scopus SJRQ1/r/bayburt/14056
  Development of Eco-Efficient Fly Ash-Based Alkali-Activated and Geopolymer Composites with Reduced Alkaline Activator Dosage

  Gökçe, H. S.; Tuyan, M.; Ramyar, K.; Nehdi, M. L.

  The eco-efficiency and economy of geopolymer composites largely depend on their alkaline activator dosage. In this study, the effect of applying a pre-setting pressure and variation of the aggregate-to-fly ash ratio on the alkaline solution dosage and mechanical strength of fly ash-based geopolymer composites was explored. It is shown that through control of the aggregate-to-ash ratio and application of pre-setting pressure, compressive strength could be increased by 102% and 86% for Class F fly ash-based geopolymer and alkali-activated Class C fly ash-based mixture, respectively. The total alkaline solution consumption could be reduced from 718 to 188 kg/m(3) and from 769 to 262 kg/m3 for Class F fly ash-based geopolymer and alkali-activated Class C fly ash-based mixture, respectively. The proposed method reduced the alkaline solution consumption per compressive strength (6.2 kg.m(-3).MPa-1) by up to 85% compared to that of the reference manually consolidated control geopolymer. The findings demonstrate that fly ash-based geopolymers could be made more sustainable and eco-efficient through tailored production techniques. (C) 2019 American Society of Civil Engineers.

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  AtıfWoS23·OpenAlex30

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• MakaleYalnız künye2019Scopus SJRQ1/r/bayburt/14103
  Assessment of Alternative Segregation Test Methods for Self-Consolidating Heavyweight Concrete

  Gökçe, H. Suleyman; Aksan, Umut; Andiç-Çakir, Ozge

  This investigation is focused on the use of alternative segregation test methods on high-performance self-consolidating heavyweight concrete. Many segregation test methods have been developed by researchers up to now; however, the disadvantages of these methods, such as being time-consuming, the requirement of excessive labor, and the lack of precision, cannot ensure their worldwide prevalence. In the study, the segregation limitations stated in various test methods, that is, the column test, density variation method, and 3-compartment sieve test, were evaluated on self-consolidating heavyweight concrete produced with barite aggregate. For this purpose, in total, eight self-consolidating heavyweight concrete mixtures designed in two water/binder ratios were prepared by replacing viscosity modifier, silica fume, and fly ash with ordinary Portland cement in different amounts. The mixtures were constituted in satisfactory segregation grades, allowing researchers to evaluate the relationship between those methods. The segregation coefficient limits of the column test, density variation method, and 3-compartment sieve test are recommended as 7%, 1%, and 6.3% for the self-consolidating heavyweight concrete mixtures tested in the study.

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  AtıfWoS5·OpenAlex7

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