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    Investigation of mechanical properties of high-performance hybrid fiber concretes adding nanomaterials using with coarse aggregate
    (Elsevier Science Inc, 2021) Oksuzer, Nurullah; Anil, Ozgur; Aldemir, Alper; Sahmaran, Mustafa
    High-performance hybrid fiber cement composites have more ductility and higher strength than traditional concrete. This is because crack development is limited due to multiple small cracks are formed instead of a single large crack as the fibers enter the matrix. It is customary to produce these concrete composites with fine aggregates. In this study, concrete composites with coarse aggregates were strived to be produced to gain some feasibility. To this end, different mixtures composed of different aggregate/binder ratios and different fly ash/ binder ratios were designed. In order to compare the effectiveness of the combination of different fibers were utilized in these mixtures. The volumetric ratios of fibers (excluding reference samples) were kept constant at a value of 2%. For each mixture, four-point bending and compressive tests were performed. The increase in the aggregate ratio was observed to cause a more ductile flexural behavior in mixtures composed of PVA and steel fibers. In contrast, the ductility was reduced in mixtures with Nylon-mono and steel fibers. In addition, the ductility values were enhanced with the increase in FA/PC ratio. In addition, the possibility to use the cheaper Nylon-mono fibers in hybrid fiber mixtures was proved with optimization of aggregate-binder (A/B) and FA/PC ratios, enabling more feasible high-performance concrete mixtures.
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    Investigation of Shear Span to Depth Ratios and Failure Modes on High Performance Hybrid Fibre Reinforced Concretes by Using Coarse Aggregate
    (Bayburt University, 2021) Öksüzer, Nurullah; Anıl, Ozgur; Aldemir, Alper; Şahmaran, Mustafa
    Small scale studies in the laboratories of high performance concretes with hybrid fiber additives are quite common. However, large-scale studies on these special concretes are very difficult to do research due to reasons such as cost and production difficulty. Studies on these concretes with different shear span/effective depth (a / d) ratios have not yet become widespread. In order for these concretes to be used structurally, the cost reduction should be considered as a priority. This study started with the use of coarse aggregate (Dmax 11.2mm) in order to reduce the cost of these special concretes. In addition, two different ratios of fly ash (0.20-0.70), two different ratios of aggregate (1.0-2.0) and 3 different fiber types (Steel, Nylon and PVA) with different lengths were also evaluated within the scope of the study. Two different nano materials were added to a series selected among the mixtures and participated in the performance evaluation. The reinforced concrete mixture, which is widely used in structural productions today, was produced within the scope of the study in order to make a comparison. Beams of 100x150x1000 mm were produced from the mixtures and four-point bending loadings were applied at four different a/d (0.67, 1.11, 2.22 and 2.96) ratios. At the end of 28 days, the load-displacement curves and fracture patterns of the beams obtained from the experiments were examined and evaluated.