Browsing by Author "Akcaozoglu, Semiha"

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Effect of Granulated Blast Furnace Slag and fly ash addition on the strength properties of lightweight mortars containing waste PET aggregates
(ELSEVIER SCI LTD, 2011) Akcaozoglu, Semiha; Atis, Cengiz Duran; 0000-0003-3459-329X; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Atis, Cengiz Duran
In this work, the effect of Granulated Blast Furnace Slag (GBFS) and fly ash (FA) addition on the strength properties of lightweight mortars containing waste Poly-ethylene Terephthalate (PET) bottle aggregates was investigated. Investigation was carried out on three groups of mortar specimens. One made with only Normal Portland cement (NPC) as binder, second made with NPC and GBFS together and, third made with NPC and FA together. The industrial wastes mentioned above were used as the replacement of cement on mass basis at the replacement ratio of 50%. The size of shredded PET granules used as aggregate for the preparation of mortar mixtures were between 0 and 4 mm. The waste lightweight PET aggregate (WPLA)–binder ratio (WPLA/b) was 0.60; the water–binder (w/b) ratios were determined as 0.45 and 0.50. The dry unit weight, compressive and flexural–tensile strengths, carbonation depths and drying shrinkage values were measured and presented. The results have shown that modifying GBFS had positive effects on the compressive strength and drying shrinkage values (after 90 days) of the WPLA mortars. However, FA substitution decreased compressive and flexural–tensile strengths and increased carbonation depths. Nevertheless a visible reduction occurred on the drying shrinkage values of FA modifying specimens more than cement specimens and GBFS modified specimens. The test results indicated that, GBFS has a potential of using as the replacement of cement on the WPLA mortars by taking into consideration the characteristics. But using FA as a binder at the replacement ratio of 50% did not improve the overall strength properties. Although it was thought that, using FA as binder at the replacement ratio of 50% for the aim of production WPLA concrete which has a specific strength, would provide advantages of economical and ecological aspects.
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 Duran; 0000-0003-3459-329X; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Atis, Cengiz Duran
In 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.