Scopus İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/395
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Article Citation - WoS: 8Citation - Scopus: 8Very High Early Strength Calcium Aluminate Based Binary and Ternary Cementitious Systems: Properties, Hydration and Microstructure(Taylor & Francis Ltd, 2023-06-16) Saydan, Murat; Keskin, Ulku Sultan; Uzal, BurakCalcium aluminate cement (CAC) is a cement type that has superior properties such as rapid strength gain, high resistance to high temperatures and harmful chemicals. However, the result of the using of CACs in the production of structural elements occur strength decreases at later ages as a result of a series of chemical reactions called 'conversion reactions' seen in these cements. In this study, the hydration kinetics and the crystalline and amorphous structures formed as a result of hydration were investigated in CAC containing different amounts and types of main oxides-based binary and ternary systems. Considering the results obtained, the main hydration product seen in these specimens was ettringite. Unlike many studies in the literature, metastable structures which cause conversion reactions, such as CAH(10), C(2)AH(8), have not been observed. Instead of conversion of the phases, ettringite needles were became thin and elongate which causes the paste structure porous and thus causing expansion and strength reduction at the later stages of hydration in some mixtures produce high amounts of ettringite. On the other hand, it is understood that the formation of stratlingite was limited strength decreases in systems where high silica fume is used.Article Compatibility of Superplasticizers With Natural Pozzolan Blended Cement: Multi-Criteria Compatibility Index Through Rheology and Hydration Kinetics(Taylor & Francis Ltd, 2025-08-09) Argin, Gizem; Uzal, BurakAn effective technique to decrease carbon dioxide emissions in the cement industry is the partial replacement of clinker with supplemental cementitious materials (SCMs). Given the restricted supply of by-product SCMs such fly ash, blast furnace slag, and silica fume, natural pozzolans provide viable options in the manufacturing of blended cement. In cementitious systems with natural pozzolans, the use of superplasticizers is essential to compensate for the reduced workability caused by their higher water demand. This study investigates the compatibility of different superplasticizer types, administered at similar dosages, with Portland cement containing 40% natural pozzolan, focusing on paste rheology and hydration kinetics. A Multi-Criteria Compatibility Index (MCCI) was created to provide a comprehensive and quantitative evaluation of compatibility between natural pozzolans and different types of superplasticizers, utilizing rheological and hydration kinetics within a weighted scoring framework. The assessment findings indicated that PMS displayed the best overall compatibility, principally owing to its improved hydration properties, but PNS revealed enhanced performance in rheological characteristics. PCA demonstrated restricted compatibility in both categories. The MCCI framework delivered a balanced and thorough comparison unattainable by single-parameter studies, providing a solid methodological foundation for future study on SCM-admixture compatibility.