Yüksek Lisans Tezi Görüntüleme | |||||||||||||||||||||
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Concrete mixtures with strength levels closed to concrete grade C25/30 were produced. The concrete mixtures investigated were without mineral additive, with silicafume and with fly ash, respectively. The objective of this investigation was to measure and improve the slump losses of concrete mixtures resulting from prolonged mixing by using asuperplasticizer chemical admixture. Each mixture was thoroughly mixed for five minutes to accomplish homogeneityand then slump, temperature, air content, and unit weight of the concrete mixture were measured, respectively. Cube specimens of 15 cm were prepared for 28-day compressivestrength measurement. At the end of each mixing period a certain amount of a superplasticizer was used to restore the slump of concrete at the initial slump level ofconcrete mixture were measured and then cube specimens were also prepared for 28-day compressive strength measurements. The amount of superplasticizer used for restoring the slump of each concretemixture was determined and in this way the effectiveness of superplasticizer in restoring the slump of concrete mixture in associated with fly ash and silica fume used wasunderlined. Based on the measurements obtained at the end of the investigation, it has beenobserved that, depending on the mixing time, the slump losses of concrete mixtures incorporating fly ash and silica fume were different from concrete mixtures withoutmineral additives and in relation with this the amount of superplasticizer used for restoring the slump losses of concrete mixtures was also changed.Keywords: Workability, Slump loss, Fly ash, Silica fume, Retempering, Superplasticizers | |||||||||||||||||||||