Browsing by Author "Yeşilmen, Seda"

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Bor katılmış aktif belitli çimento ve Portland çimento betonlarının mekanik özelliklerinin kıyaslanması
(2010) Apaydın, Berksan; Yeşilmen, Seda; Department of Civil Engineering
Betonun ana bileşenlerinden biri çimentodur. Kullanılan çimento türü betonun mukavemeti, dayanımı, ve dayanımından kaynaklı diğer özelliklerini etkilemektedir. Yeni bir çimento türü olan bor katılmış aktif belitli (BAB) çimento üzerinde ticari olarak kullanmak amaçlı araştırmalar sürmektedir. Bu tezde, depolama tesislerinde uzun süre beklemiş bor katılmış aktif belitli çimento ile geniş bir kullanım alanı olan Portland çimentosu (OPC) performansları kıyaslanmıştır. Tez kapsamında Atılım Üniversitesi, İnşaat Mühendisliği Bölümü ve Devlet Su İşleri-Teknik Araştırma ve Kalite Kontrol Dairesi Başkanlığı (DSİ-TAKK) laboratuvarlarında bir dizi laboratuvar deneyi yapılmıştır. Bu deneylerin sonuçlarına göre, yaşlanmış BAB çimento ile Portland çimentosu yaklaşık aynı mekanik performansı göstermiştir. Öte yandan, BAB çimentonun kullanımı betonda daha düşük su işleme derinliği ve boşlukluluk oranı; dolayısıyla artmış dayanıklılık sağlamıştır.
Citation Count: 4
Evaluation of Boron Ore in Cement Production
(Taylor & Francis inc, 2012) Yesilmen, Seda; Gurbuz, Ayhan; Department of Civil Engineering
A new genre of high belite cement named boron-modified active belite (BAB) cement that was developed using byproduct of boric acid production was investigated. The cement proved superior in compressive strength and permeability characteristics in the previous studies. Long term storage of cement is known to alter the mechanical properties of concrete made with the aged cement. The article investigated the BAB cement in aged condition-stored in silos for about three years-variations of mechanical and physical properties of specimens during a one-year period. An additional comparison is also performed with specimens cast using fresh Ordinary Portland Cement (OPC) of the same grade in order to present the development of mechanical and physical properties in a qualitative manner. Lower 28 day compressive strength values are observed for BAB cement compared to OPC specimens; however, higher rate of strength development of BAB cement resulting from high belite content led to comparable long term strength values with OPC specimens.
Citation Count: 50
Pull-out behavior of prestressing strands in steel fiber reinforced concrete
(Elsevier Sci Ltd, 2012) Baran, Eray; Akis, Tolga; Yesilmen, Seda; Civil Engineering; Department of Civil Engineering
This paper presents the results of an experimental study investigating the effects of steel fibers on the mechanical properties of concrete and the enhancement of bond strength of prestressing strands in steel fiber reinforced concrete (SFRC). The first part of the experimental program consisted of compression, tension and flexural tests on SFRC. Two types of steel fibers with 30 mm and 60 mm fiber lengths were used with five different fiber contents. The second part of the study consisted of simple pull-out tests on 12.7 mm and 15.2 mm diameter seven-wire untensioned prestressing strands embedded in concrete blocks. The pull-out tests were conducted with two different fiber lengths and five different fiber contents for each strand diameter. The steel fibers were observed to improve the pull-out resistance of strands by controlling the crack growth inside concrete blocks. (C) 2011 Elsevier Ltd. All rights reserved.
Citation Count: 11
Use of UHPC in Bridge Structures: Material Modeling and Design
(Hindawi Ltd, 2012) Gunes, Oguz; Yesilmen, Seda; Gunes, Burcu; Ulm, Franz-Joseph; Department of Civil Engineering
Ultra-high-performance concrete (UHPC) is a promising new class of concrete material that is likely to make a significant contribution to addressing the challenges associated with the load capacity, durability, sustainability, economy, and environmental impact of concrete bridge infrastructures. This paper focuses on the material modeling of UHPC and design of bridge girders made of UHPC. A two-phase model used for modeling the behavior of UHPC was briefly discussed, and the model was implemented in a preliminary design case study. Based on the implemented design and the reported use of UHPC in bridge applications, the advantages, limitations, and future prospects of UHPC bridges were discussed, highlighting the need for innovative research and design to make optimum use of the favorable properties of the material in bridge structures.