Mardani A., Kaya Y., Kaya T., Hatungimana D.
MATERIALS, cilt.19, sa.22, ss.1-23, 2026 (SCI-Expanded, Scopus)
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Yayın Türü:
Makale / Tam Makale
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Cilt numarası:
19
Sayı:
22
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Basım Tarihi:
2026
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Doi Numarası:
10.3390/ma19224831
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Dergi Adı:
MATERIALS
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Derginin Tarandığı İndeksler:
Academic Search Ultimate (EBSCO), Engineering Source (EBSCO), Scopus, Materials Science & Engineering Collection (ProQuest), Technology Collection (ProQuest), Science Citation Index Expanded (SCI-EXPANDED), Compendex, INSPEC
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Sayfa Sayıları:
ss.1-23
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Bursa Uludağ Üniversitesi Adresli:
Evet
Özet
Geopolymer concrete produced from fly ash and ground granulated blast furnace slag (GGBFS) has been proposed as a lower-carbon alternative to Portland cement concrete, and blending the two precursors allows for curing at ambient temperature. However, the combined influence of the precursor proportion and activator formulation on the durability of such concretes is not well documented, because mechanical and durability properties have mostly been studied separately. The objective of this study was therefore to evaluate, within a single experimental programme, how the fly ash-to-slag proportion and three combined activator formulations affect the fresh, mechanical and durability properties of ambient-cured hybrid geopolymer concrete. This study examines the influence of the fly ash-to-slag proportion and of three combined activator formulations (nominal Si/Al of 2.0, 2.5 and 3.0, each paired with an SS/SH ratio of 1.5, 2.0 and 2.5, respectively) on the fresh-state, mechanical, and durability characteristics of ambient-cured hybrid geopolymer concrete. Twelve mixture compositions were systematically designed at a constant binder content (500 kg/m3) and NaOH concentration (10 M); the alkaline solution-to-binder ratio varied from 0.33 to 0.39 with the activator formulation. Because Si/Al and SS/SH were varied together, their individual effects could not be separated. Progressive augmentation of the GGBFS proportion from 20% to 50% increased strength and improved the measured durability indicators, while reducing slump and setting time. The best-performing mixture in most tests (M11: 50% GGBFS, nominal Si/Al = 2.5, SS/SH = 2.0) attained a 28-day compressive strength of 60.3 MPa, water absorption of 3.8%, ultrasonic pulse velocity of 4.79 km/s and the lowest freeze–thaw strength loss (4.8%); the highest formulation (M12) was marginally better in the 90-day sulfate test (1.9% versus 2.0% strength loss). Conversely, the highest activator formulation (Si/Al = 3.0, SS/SH = 2.5) slightly reduced strength and increased shrinkage and freeze–thaw strength loss relative to the intermediate one; a viscosity-related limitation of ion mobility is a possible but unverified explanation. These outcomes show that precursor blending and activator formulation strongly affect the laboratory performance of ambient-cured fly ash–GGBFS geopolymer concrete; structural suitability, field durability and environmental benefit were not assessed.