Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Develepment of a New Test Method To Evaluate Dynamic Stability of Self-Consolidating Concrete(Izmir Institute of Technology, 2014) Alami, Mohammad Musa; Erdem, Tahir KemalSelf-consolidating concrete (SCC) is a new generation of concrete with high performance. It is able to flow under its own weight and fills the formwork without any external vibration. Stability is the most important plastic and crucial property for successful application of SCC and it refers to segregation of constituent in fresh state. Dynamic stability is the segregation resistance of SCC during transportation and placement. Evaluation of dynamic stability is one of the most investigated topics of SCC. Many different test methods have been proposed to evaluate the dynamic stability of SCC. No single and widely accepted method exists for the evaluation of the dynamic stability of SCC. In this thesis a new apparatus for testing the dynamic stability of SCC was developed. The effect of different mix design parameters such as water-to-cement ratio w/c, slump flow diameter, coarse aggregate-to-total aggregate ratio (CA/TA), and maximum size of aggregate (Dmax) were evaluated on the dynamic stability of SCC. Several fresh concrete tests were carried out on the SCC mixtures: slump flow, T500 time, Visual stability index (VSI), V-funnel, L-box, static sieve segregation (GTM), rheometer, and new proposed method (DSST). Several correlations were established between the test results. It was found that the new proposed test is a suitable method to evaluate the dynamic stability of SCC. Limits were proposed for a dynamically stable SCC.Master Thesis Effects of Thixotropy on Self Consolidating Concrete Surface Properties(Izmir Institute of Technology, 2012) Ersöz, Hasan Yavuz; Erdem, Tahir KemalSelf-consolidating concrete is a high performance concrete that does not require vibration for placing and compaction. It is able to flow under its own weight compeletly filling the formwork and achieving full compaction. Self consolidating concrete reduces construction time and cost, also faults resulting from the poor workmanship. In this thesis, the effects of thixotropy on surface properties and durability were investigated. Concrete Mixtures were produced with different three slump flows (55 cm , 65 cm , 72 cm). Rheology and thixotropy of fresh concrete were examined by Contec 4SCC concrete rheometer. To obtain different surfaces, following parameters were changed: Thixotropy (by changing slump flow), release agent (six different types), formwork type (steel, plexiglas, plywood) and pressure application (equivalent to the weight of 10 m high fresh SCC) on specimens during setting. Concrete specimen surfaces were captured and digitally recorded on a hard drive. Digital images were analyzed by an image processing software, Image J. Compatibility of mixture type, material and release agent varieties was studied to minimize voids on surfaces. In the last stage of the thesis, durability and permeability of selected mixtures were investigated by performing sorptivity permeability, salt scaling and chloride ion penetration tests. It was found that, the surface quality depends on both thixotropy and release agent. Moreover, the release agent has to be selected according to the formwork material. In other words, for best surfaces release agent, formwork material and thixotropy have to be considered simultaneously. In general plywood formworks resulted in better surfaces in comparison to steel and plexiglas. Furthermore surfaces exposed to pressure gave better results. At the end of this work a table was prepared to make surface categorization which can be used as a reference for future works.