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Öğe An investigation on the use of shredded waste PET bottles as aggregate in lightweight concrete(PERGAMON-ELSEVIER SCIENCE LTD, 2010) Akcaozoglu, Semiha; Atis, Cengiz Duran; Akcaozoglu, KubilayIn this work, the utilization of shredded waste Poly-ethylene Terephthalate (PET) bottle granules as a lightweight aggregate in mortar was investigated. Investigation was carried out on two groups of mortar samples, one made with only PET aggregates and, second made with PET and sand aggregates together. Additionally, blast-furnace slag was also used as the replacement of cement on mass basis at the replacement ratio of 50% to reduce the amount of cement used and provide savings. The water-binder (w/b) ratio and PET-binder (PET/b) ratio used in the mixtures were 0.45 and 0.50, respectively. The size of shredded PET granules used in the preparation of mortar mixtures were between 0 and 4 mm. The results of the laboratory study and testing carried out showed that mortar containing only PET aggregate, mortar containing PET and sand aggregate, and mortars modified with slag as cement replacement can be drop into structural lightweight concrete category in terms of unit weight and strength properties. Therefore, it was concluded that there is a potential for the use of shredded waste PET granules as aggregate in the production of structural lightweight concrete. The use of shredded waste PET granules due to its low unit weight reduces the unit weight of concrete which results in a reduction in the death weight of a structural concrete member of a building. Reduction in the death weight of a building will help to reduce the seismic risk of the building since the earthquake forces linearly dependant on the dead-weight. Furthermore, it was also concluded that the use of industrial wastes such as PET granules and blast-furnace slag in concrete provides some advantages, i.e., reduction in the use of natural resources, disposal of wastes, prevention of environmental pollution, and energy saving. (C) 2009 Elsevier Ltd. All rights reserved.Öğe Artificial Intelligence Approach in Predicting the Effect of Elevated Temperature on the Mechanical Properties of PET Aggregate Mortars: An Experimental Study(Springer Heidelberg, 2021) Colak, Andac Batur; Akcaozoglu, Kubilay; Akcaozoglu, Semiha; Beller, GulhanIn this study, the effect of high temperature on the flexural and compressive strength of mortars containing waste PET aggregates was investigated experimentally. The mortar samples prepared in 5 different concentrations with a total of 2.5%, 5%, 10%, 20% and 30% PET aggregate substitution were heated up to 100, 150, 200, 250, 300 and 400 degrees C. After waiting for 1, 2 and 3 h at these temperatures, flexural and compressive strength tests were performed. It was observed that flexural strength and compressive strength values decreased with increasing temperature and PET aggregate amounts in all mixtures. An artificial neural network was designed to estimate flexural and compressive strength values using experimental data. It has been observed that the developed artificial neural network can predict flexural and compressive strengths with an average error of - 0.51%.Öğe Effect of calcined perlite content on elevated temperature behaviour of alkali activated slag mortars(Elsevier, 2020) Celikten, Serhat; Saridemir, Mustafa; Akcaozoglu, KubilayIn this paper, the influence of calcined perlite on the elevated temperature behaviour of alkali activated slag (AAS) mortars is researched. The diversity parameters of mortars are the levels of calcined perlite (CP) replacement (0, 25 and 50% by volume), the molecular silicate modulus (0.25, 0.50, 0.75, 1.00 and 1.25) and the levels of elevated temperature (400 degrees C, 600 degrees C and 800 degrees C). The flexural strength (f(f)), compressive strength (f(e)) and mass loss of mortars produced according to these diversity parameters are determined. Moreover, X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) analyses are performed on the samples from the mortars exposed to ambient and elevated temperatures. The experimental results prove that the initial f(f) and f(e) results of mortars at ambient temperature significantly reduce with the increase of CP content. This decrease in the f(f) and f(e) results of mortars is confirmed by the mass losses and microstructure analysis. On the other hand, the experimental results prove that there are significant improvements in the residual strengths of mortars at elevated temperatures with the increase of CP content.Öğe Investigation of the bacterial modified waste PET aggregate VIA Bacillus safensis to enhance the strength properties of mortars(Elsevier Sci Ltd, 2021) Akcaozoglu, Semiha; Adiguzel, Ali Osman; Akcaozoglu, Kubilay; Deveci, Ece Ummu; Gonen, CagdasPolyethylene terephthalates (PET), which are highly resistant to degradation under natural environmental conditions due to their inert, hydrophobic and high molecular weights, are collected in landfills or dispersed as waste. Considering the increasing use of PET, the interest in multidisciplinary studies aimed to obtaining high value added products from PET wastes has increased. In this study, the potential of using waste plastics made of Polyethylene terephthalate (PET) treated with bacteria as an aggregate in the production of mortar was investigated. First, the bacterial strains, which secreted esterase or cutinase, were screened for their ability to attach to hydrophobic surfaces and biofilm formation. TH401, which showed potential for the modification of the PET aggregates, was identified as Bacillus safensis. To enhance the compatibility of the PET, the waste PET aggregates were treated with submerged fermentation via B. safensis TH401. The FTIR analyses conducted after the treatment showed that the chemical structure of the PET had been modified. Mortar samples were prepared by using the modified PET aggregates. The compressive and flexural tensile strength values of the samples were measured on days 7, 28 and 56. The compressive strength values of the bacteria modified samples were 4.87%, 7.51% and 13.13% higher than the non-bacterial samples at 22 degrees C, 30 degrees C and 50 degrees C, respectively. The increase in curing temperatures had a positive effect on compressive and flexural tensile strength values. The highest strength values were obtained in the samples cured at 50 degrees C. In the EDX spot of the mixtures, major peaks of C, O, Ca were detected indicating the presence of CaCO3 and bacteria. Stratification on the PET surface as a result of bacterial modification was clearly observed in the SEM images. The test results showed that bacterial modification contributed to the increase in the strength of the waste PET aggregate concrete. It can be said that mortars produced with bacteria modified PET aggregates can be used as an economical and environmentally friendly material alternative in the construction industry. (C) 2020 Elsevier Ltd. All rights reserved.Öğe INVESTIGATION OF THE USE OF ENVIRONMENTALLY FRIENDLY BINDERS IN THE PRODUCTION OF SIFCON MATRIX(Parlar Scientific Publications (P S P), 2020) Akcaozoglu, Kubilay; Ozcan, SumeyyeIn this study, blast furnace slag (BFS) and fly ash (FA) which are industrial waste were used as binders instead of cement used in the production of SIFCON slurry. For this purpose, control mixture and alkali activated mixtures were prepared in four different series as 100% FA, 50% FA- 50% BFS, 100% BFS. Na ratios of alkali activators used in mixtures were 4%, 6% and 8%. Viscosity, hardened unit weight, compressive strength, flexural tensile strength and ultrasonic pulse velocity tests were performed on the samples. The viscosity values of the alkali-activated. BFS mixtures were similar to the control mixtures as the spindle rotation speed increased. The compressive strength values of alkali activated BFS samples were higher than control samples and alkali activated FA samples. The flexural tensile strength and ultrasonic pulse velocity values of alkali activated samples were lower than the control sample. As a result of the study, it has been seen that alkali-activated BFS mixtures can be used in the production of SIFCON slurry. The use of industrial wastes as a binder in SIFCON production will contribute to reducing natural resource consumption. recycling resources, conserving energy and protecting the environment.Öğe Investigation of the use of environmentally friendly binders in the production of sifcon matrix(Parlar Scientific Publications, 2020) Akcaozoglu, Kubilay; Ozcan, SumeyyeIn this study, blast furnace slag (BFS) and fly ash (FA) which are industrial waste were used as binders instead of cement used in the production of SIFCON slurry. For this purpose, control mixture and alkali activated mixtures were prepared in four different series as 100% FA, 50% FA- 50% BFS, 100%) BFS. Na ratios of alkali activators used in mixtures were 4%, 6% and 8%. Viscosity, hardened unit weight, compressive strength, flexural tensile strength and ultrasonic pulse velocity tests were performed on the samples. The viscosity values of the alkali-activated BFS mixtures were similar to the control mixtures as the spindle rotation speed increased. The compressive strength values of alkali-activated BFS samples were higher than control samples and alkali activated FA samples. The flexural tensile strength and ultrasonic pulse velocity values of alkali activated samples were lower than the control sample. As a result of the study, it has been seen that alkali-activated BFS mixtures can be used in the production of SIFCON slurry. The use of industrial wastes as a binder in SIFCON production will contribute to reducing natural resource consumption, recycling resources, conserving energy and protecting the environment. © by PSPÖğe Microstructural examination of concrete exposed to elevated temperature by using plane polarized transmitted light method(ELSEVIER SCI LTD, 2013) Akcaozoglu, KubilayIn this study, the influence of elevated temperature on the residual compressive strength and ultrasonic wave velocity of the concrete specimens has been investigated. In addition, the effect of elevated temperature on the aggregate-cement paste interface and aggregate microstructure of the concrete specimens was also has been examined by plane polarized transmitted light (PPTL) method. Investigation was carried out by using one concrete mixture which was produced by normal Portland cement (PC), quartzitic natural sand and crushed basaltic coarse aggregate. The water-cement (w/c) ratio used in the mixtures was 0.50. The produced concrete specimens were exposed to 200, 400, 600, 800 and 1000 C. Test results indicated that the residual compressive strength and ultrasonic wave velocity values of the concrete specimens decreased depending on increase in elevated temperature. In addition PPTL examinations showed that, increasing temperature caused weakening of the adherence of aggregate and cement matrix. Film layers and discontinuities observed in the aggregate-cement matrix depend on increasing temperature. Fast cooling (FC) method resulted in strength losses when compared to slow cooling (SC) method.Öğe Microstructural examination of the effect of elevated temperature on the concrete containing clinoptilolite(ELSEVIER SCI LTD, 2014) Akcaozoglu, Kubilay; Fener, Mustafa; Akcaozoglu, Semiha; Ocal, RecepIn this study, the effect of elevated temperature on the properties of concrete containing clinoptilolite was investigated by microscopic analyses. For this purpose, seven different mixtures were prepared (the control mixture and six mixtures including 5%, 10%, 15%, 20%, 30% and 40% clinoptilolite by weight). The water binder (w/b) ratio used in the mixtures was 0.475. The dry unit weights, water absorption ratios, porosity ratios, compressive strengths and thermal conductivity coefficients of the mixtures were measured. In addition the specimens exposed to elevated temperatures of 250, 500,750 and 1000 degrees C. Two different cooling methods were used (slow cooling and fast cooling). The residual compressive strengths of the specimens which were exposed to elevated temperatures were measured. In addition the mineral and texture changes of the specimens were examined by using plane polarized microscope. Test results indicated that, clinoptilolite substitution decreased the compressive strength of the specimens in early days, but increased at later days. The positive effects were observed about clinoptilolite substitution on the residual compressive strength of the specimens. It was observed from microscopic analyses that, as the amount of clinoptilolite increased in the mixtures, aggregates were less affected from elevated temperatures. Fast cooling (FC) method resulted in strength losses when compared to slow cooling (SC) method. Additionally, clinoptilolite substitution decreased the thermal conductivity coefficient of the concrete. (C) 2014 Elsevier Ltd. All rights reserved.Öğe The effect of curing conditions on the mechanical properties of SIFCON(Pontificia Univ Catolica Chile, Escuela Construccion Civil, 2021) Akcaozoglu, Kubilay; Killi, AdemIn this study, the effect of curing conditions on the mechanical properties of slurry infiltrated fiber reinforced concrete (SIFCON) was investigated. For this purpose, SIFCON samples containing 4% and 8% steel fiber with two different aspect ratios were produced. The samples were subjected to three different curing types, namely standard, dry and accelerated curing methods. Ultrasonic wave velocity, flexural strength, fracture toughness, compressive strength, impact resistance and capillary water absorption tests were performed on the samples. The highest flexural strength was found to be achieved in the samples with an aspect ratio of 55 and a content of 8% steel fiber. The most suitable curing method was determined as the standard curing method and the best flexural strength was achieved at the rate of 8%. According to the test results, the best strength properties were achieved in the samples exposed to the standard curing method. In addition, the samples exposed to the accelerated curing method showed satisfactory values. The accelerated curing method can be used as an alternative in SIFCON production especially in applications requiring mass production.Öğe Thermal conductivity, compressive strength and ultrasonic wave velocity of cementitious composite containing waste PET lightweight aggregate (WPLA)(ELSEVIER SCI LTD, 2013) Akcaozoglu, Semiha; Akcaozoglu, Kubilay; Atis, Cengiz DuranIn this study, the influence of waste PET as lightweight aggregate (WPLA) replacement with conventional aggregate, on thermal conductivity, unit weight and compressive strength properties of concrete composite was investigated. For this purpose, five different mixtures were prepared (the control mixtures and four WPLA mixtures including 30%, 40%, 50%, and 60% waste PET aggregate by volume). Thermal conductivity (TC) coefficients of the specimens were measured with guarded hot plate apparatus according to TS ISO 8302 [1]. The thermal conductivity coefficient, unit weight and compressive strength of specimens decreased as the amount of WPLA increased in concrete. The minimum thermal conductivity value was 0.3924 W/m K, observed at 60% WPLA replacement. From this result, it was concluded that waste PET aggregates replacement with conventional aggregate in the mixture showed better insulation properties (i.e. lower thermal coefficient). Due to the low unit weight and thermal conductivity values of WPLA composites, there is a potential of using WPLA composites in construction applications. (c) 2012 Elsevier Ltd. All rights reserved.
