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Öğe Aggressive Environment Performance of Low Energy Cements Containing Fly Ash(Gazi Univ, 2021) Gokce, H. Suleyman; Simsek, OsmanIn this study, compressive strength performance of boron active belite cement containing fly ash at the ratios of 0, 10, 20, and 30% (by weight of cement) is researched against aggressive environments; sea water, 5% sodium sulphate solution, and 5% ammonium nitrate solution in addition to tapping water. Alternative low energy cement i.e., Portland-composite cement was used and its results were compared with those of boron active belite cement. Early strength losses (reaching up to 40%) of the boron active belite cement with incorporation of fly ash up to 30% were found to be less pronounced than those (reaching up to 51%) of Portland-composite cement in tapping water. Although, the losses were highly compensated with the prolonged curing period (90 days), boron active belite cement and Portland-composite cement kept their losses up to 14% and 36%, respectively. Residual mechanical properties (reaching up to 67%) of boron active belite cement against aggressive environments were found almost similar to those of Portland-composite cement in presence of 30% fly ash. In conclusion, the study shows that belite cements with low fly ash contents can be a reasonable alternative for specific applications such as mass concrete, hot weather concreting especially in aggressive environments.Öğe DETERMINATION OF ALKALI-SILICA REACTION EFFECTS OF ZEOLITIC TUFF ADDITION ON THE DIFFERENT AGGREGATES(Gazi Univ, Fac Engineering Architecture, 2010) Gokce, H. Suleyman; Taban, Saniye; Simsek, OsmanThe aim of this study is to determine the alkali-silica reaction (ASR) related characteristics of crushed stones that are produced from rocks of perlite, andesite and limestone when zeolitic tuff (ZT) is used in the mortar mix as cement replacement in different ratios. Accelerated mortar bar experiments in accordance with ASTM C 1260 were carried out on crushed stone aggregate samples to determine the ASR. CEM I 42.5 R type cement was replaced by ZT material in the following ratios: 0, 10, 20, 30 and 40%; in order to investigate the effects of replacement on the ASR pertaining to the aggregate types, 45 mortar bar pieces were produced. The length change values of the samples were measured on the 3, 7, 14, 28, 42, 56 days according to the accelerated mortar bar method. Measured length changes for the control samples on 14(th) day were found to be 0.570% at the level of potentially harmful for perlite, 0.101% at the level of critic for andesite and 0.061% at the level of harmless for limestone. Length changes at the harmful levels were taken under control for perlite at 30 and 40%, for andesite at 20, 30 and 40% ZT replacement ratios. Length change values of all samples decrease as ZT replacement increases. As a result, ZT replacement is effective to suppress the ASR of reactive aggregates.Öğe Investigation of Usability of Basaltic Pumice Aggregate At Prefabricated Structure Light-Weight Concrete Components(Gazi Univ, 2011) Gokce, H. Suleyman; Simsek, OsmanAt prefabrication, concrete which is 30 MPa and more compressive strength is generally used in the production of structure components such as colon, beam etc. In new generation productions, expected property of the components is not only compressive strength, but also tensile splitting strength, bond strength and lightness which provides advantage on movement and molding. In this study, the engineering properties of the concrete prepared by CEM I 42.5 R type cement by using pumice and normal aggregate were investigated On determination of compressive strength 100x200 mm sized cylinder sample, on determination of tensile splitting and bond strength 150x150x150 mm sized cube sample and O12 ribbed steel bar was used. It is found that light-weight concrete (LC) which was prepared with pumice aggregate is 30% lighter than normal concrete (NC) prepared with normal aggregate and at equal strength. According to the NC, the LC was obtained by 48% less tensile splitting strength and 15% less bond strength.Öğe RESEARCH OF PESIMUM REACTIVE AGGREGATE RATIO OF THE PERLITE AGGREGATE WITH DIFFERENT METHODS(Gazi Univ, Fac Engineering Architecture, 2010) Gokce, H. Suleyman; Simsek, OsmanIn this study, it is purposed to determine of reactive aggregate ratio of the perlite aggregate for given up the highest length change. For this purpose, properties of relate to alkali-silica reaction (ASR) of the perlite aggregate determined with non-reactive limestone aggregate. For the determination of ASR, according to ASTM C 1260 accelerated mortar bar method, for microstructure; Scanning Electron Microscope (SEM) and Energy Dispersive X-ray (EDX) analysis were carried out on the samples which are perlite, limestone and used both of them. Mixtures were prepared by weight at 0, 10, 20, 30, 40, 50 and 100% ratios with usage of perlite aggregate that obtained from Ankara Cubuk region instead of limestone aggregate that obtained from Ankara Hasanoglan region. 21 pieces of mortar bars were produced for 7 different mixtures. The length change values of the samples were measured on the 3, 7, 10, 14, 21 and 28-day according to the accelerated mortar bar method. Morphology and chemical composition of highest length changed samples were determined with SEM and EDX. Increase of fracture density and Ca ratio was observed in parallel with the increase of length change. According to average of 14 days length change, 40% perlite aggregated samples underwent highest length change and these samples were determined as pesimum reactive aggregate ratio of the perlite aggregate.
