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BİRİCİK, ÖZNUR

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BİRİCİK

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ÖZNUR

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Now showing 1 - 3 of 3
  • Publication
    Effect of waste binder material usage rate on thixotropic behaviour of cementitious systems
    (Elsevier Sci Ltd, 2023-09-03) Biricik, Öznur; AYTEKİN TÜRKOĞLU, BURCU; BİRİCİK, ÖZNUR; Aytekin, Burcu; MARDANİ, ALİ; Mardani, Ali; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0003-0326-5015; C-7860-2015; JPK-8822-2023
    In order to investigate the feasibility of using waste as an alternative binder in cement-based materials, the effects of using recycled concrete powder (RCP), glass powder (GP), marble powder (MP), and limestone powder (LP) in place of portland cement on the rheological and fresh characteristics of cementitious systems were determined. In this regard, the influence of the utilization of waste materials and the substitution ratio (25% and 35%) on the parameters of the cement paste mixtures that change over time, such as setting time, Marsh-funnel flow time, mini-slump value, viscosity, and dynamic yield stress (DYS), were determined. The effect of 4 different type waste powder materials on the rheology and thixotropy of cementitious systems was investigated using two different methods (loop and constant shear strain rate methods). In order to reduce cement consumption, the effect of the use of waste powder materials on the time-dependent behavior of cementitious systems has been examined, and important results have been obtained for cases (such as producing 3D concrete or self compacting concrete) where time-dependent consistency change is important. It was determined that replacing RCP and GP enhanced the DYS values while replacing MP and LP decreased them. In this context, it was understood that regardless of time, MP and LP promote flowability, whereas RCP and GP diminish flowability. RCP35 had the greatest Ithix_shr and Ithix_vis values at the 20th minute, whereas MP and LP-containing mixtures had the lowest values. The mixtures with the highest and lowest thixotropic degrees were RCP35 and LP35, respectively.
  • Publication
    Parameters affecting thixotropic behavior of self compacting concrete and 3D printable concrete; A state-of-the-art review
    (Elsevier, 2022-05-02) Biricik, Öznur; Mardani, Ali; BİRİCİK, ÖZNUR; MARDANİ, ALİ; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü; 0000-0003-0326-5015; JPK-8822-2023; C-7860-2015
    Structural changes as a result of thixotropic behavior are very important in cementitious systems such as self compacting concrete (SCC) and 3-dimensional concrete (3D) mixtures with high binder volume. In this context, it was understood that the examination of the parameters affecting the thixotropy behavior of cementitious systems is realized by measuring the time-dependent change of the rheological properties of the mixture. For this purpose, it was understood that rheometer, measurement and comparison methods, which are quite different from each other, are used. In this study, the parameters affecting the thixotropic properties of cementitious systems; the parameters originating from cement, mineral-chemical admixtures, aggregate and mixture properties (water/binder (w/b) ratio and mixing process) were examined under the headings. In addition to these, the rheometer, measurement and evaluation methods used in the studies were examined. It was stated that the interaction between particles, bond strength of particles, flocculation and thixotropic change rate increase with the increase of cement fineness, alkali and C(3)A ratio. It was emphasized that the thixotropic property of the mixture increased with the use of mineral additives such as silica fume, limestone dust and blast furnace slag, and the reverse of this behavior was observed when fly ash was used. It was reported that the addition of clay and calcined clay to cementitious systems increases the thixotropic behavior due to its layered structure. It was emphasized that the structural build-up of cementitious systems decreases with the addition of water reducer admixtures, and increases with the addition of viscosity modifying admixtures.
  • Publication
    Effect of metakaolin utilization ratio and loop method-pre-shearing process variation on rheological properties of cementitious systems having different C3A content
    (Elsevier Sci Ltd, 2022-12-17) Biricik, Öznur; Şahin, Hatice Gizem; Mardani, Ali; BİRİCİK, ÖZNUR; Şahin, Hatice Gizem; MARDANİ, ALİ; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0002-8915-879X; 0000-0003-0326-5015; IAQ-9713-2023; JPK-8822-2023; AAJ-6415-2021; AAE-2420-2022; C-7860-2015
    Thixotropic behavior, which directly affects the fresh state properties of cementitious systems such as pump -ability, compressibility and hydrostatic mold pressure, is determined by applying the loop method, step change and constant shear rate. This behavior is seriously affected by parameters such as the type, amount and fineness of the binder and the process applied in rheological measurements. In this study, the effect of cement C3A content, metakaolin utilization ratio, resting time of the mixture, pre-shear rate and applying pre-shear rate on the thixotropic behavior of the mixtures at the beginning and 20th-minutes were investigated. For this purpose, 4 types of cement having different C3A contents (2.13%, 3.60%, 6.82% and 9.05%) were used. By testing each of the 4 cements (2.13%, 3.60%, 6.82% and 9.05%) for 5 conditions (no metakaolin, 3%, 6%, 9% and 12% met-akaolin), a total of 20 mixtures were prepared. For each cement type, 0, 3, 6, 9 and 12% of the total binder volume was replaced with metakaolin. The loop method was used to determine the rheological parameters. According to the results, irrespective of all parameters examined, the structural build-up area values were higher than the structural breakdown ones in the mixtures and the structure formation that occurred after 20 min was mostly reversible. It was determined that rheological parameters, structural build-up area value and rate of reversible structure formation increased with the increase in cement C3A content and metakaolin utilization rate. The increase in the initial dynamic yield stress values of the mixtures with the increase of the cement C3A ratio was more pronounced in the case where the measurement is made without waiting immediately after the pre -shear application. The effect of C3A content on dynamic yield stress and viscosity values was more pro-nounced with an increasing pre-shear rate. The opposite was observed for the structural build-up area values.