Browsing by Author "Öztürk A.U."
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Item Use of recycled concrete aggregates in Hot-Mix Asphalt(American Concrete Institute, 2006) Topal A.; Öztürk A.U.; Baradan B.The rubble from construction is generally used in landfill or thrown to natural areas at the end of their service life. Because continuously increasing production of concrete consumption, recycling of concrete waste materials will provide environmental protection and economical benefits. In this study, effects of fine and coarse recycled concrete aggregates on Hot-Mix Asphalt (HMA) performance were investigated. In performed experiments, Marshall Mixtures were prepared by using recycled concrete aggregates in the proportion of 10%, 20%, and 30% by mixture weight for the replacement of limestone in suitable gradation. Six different bitumen ratios were added to each mixture, respectively. Void %, flow and stability values were examined on 54 specimens. Furthermore, indirect tensile strength experiments were examined on the specimens having optimum 4.5% bitumen content and 30% recycled concrete aggregates. The results indicate that waste concrete can be used in HMA as aggregate to obtain the required Marshall stability and indirect tensile strength of the mixtures. However, the void percent of the mixture are not desirable due to the dense gradation of aggregate. Hence, gradation change is needed to Marshall Design criteria. © 2006 American Concrete Institute. All rights reserved.Item Determination of reducing coefficient values of semi-rigid frames using artificial neural network(Association for Scientific Research, 2011) Şeker S.; Öztürk A.U.; Kozanoǧlu C.Lateral rigidity is a great issue in the view of structural analysis in civil engineering applications such as production of buildings, bridges, dams and roads. Furthermore, the connection properties have a remarkable role on the lateral rigidity and the tendency of structures under service loads. In fact, there aren't any structures with perfectly rigid connections between beams and columns. Therefore, all connections performed by construction process can be defined as semi-rigid as, especially connections in steel structures. The effect of connection type on the lateral rigidity values of structures can be determined by reducing coefficients decreasing lateral rigidity with a certain extent. In the scope of this study, connection flexibility is modeled by linear elastic rotational springs for semi-rigid frames. The reducing coefficients are determined by using a computer program. Results are compared to the values predicted by artificial neural network (ANN) analyses. A strong relationship was established between calculated and predicted values. © Association for Scientific Research.Item Cost optimization of mortars containing different pigments and their freeze-thaw resistance properties(Hindawi Publishing Corporation, 2016) Yildizel S.A.; Kaplan G.; Öztürk A.U.Nowadays, it is common to use colored concrete or mortar in prefabricated concrete and reinforced concrete construction elements. Within the scope of this study, colored mortars were obtained with the addition of brown, yellow, black, and red pigments into the white cement. Those mixtures are examined for their compressive strength, unit weight, water absorption, and freeze-thaw resistance. Subsequent to comparison of these properties, a cost optimization has been conducted in order to compare pigment costs. The outcomes showed that the pore structure in architectural mortar applications plays an important role in terms of durability. And cost optimization results show that light colored minerals can be used instead of white cements. © 2016 Sadik Alper Yildizel et al.Item A study on the estimation of prefabricated glass fiber reinforced concrete panel strength values with an artificial neural network model(Tech Science Press, 2016) Yildizel S.A.; Öztürk A.U.In this study, artificial neural networks trained with swarm based artificial bee colony optimization algorithm was implemented for prediction of the modulus of rapture values of the fabricated glass fiber reinforced concrete panels. For the application of the ANN models, 143 different four-point bending test results of glass fiber reinforced concrete mixes with the varied parameters of temperature, fiber content and slump values were introduced the artificial bee colony optimization and conventional back propagation algorithms. Training and the testing results of the corresponding models showed that artificial neural networks trained with the artificial bee colony optimization algorithm have remarkable potential for the prediction of modulus of rupture values and this method can be used as a preliminary decision criterion for quality check of the fabricated products. © 2016 Tech Science Press.Item A study of some durability properties of mortars with white cement and Portland cement; [Studiul unor caracteristici de durabilitate ale mortarelor preparate cu ciment alb şi ciment Portland](Fundatia Serban Solacolu, 2017) Öztürk A.U.; Kaplan G.Workability, strength and durability are among the most important properties when working with concrete. Increased compressive strength of concrete has favorable impact on durability along with on its several other features. To ensure a high degree of durability, it is essential that clean, sound materials and the lowest possible water content are used in the concrete, together with thorough mixing. Good consolidation during placement of the concrete is important, as are proper curing and protection of the concrete during the early hardening period, which assure favorable conditions of temperature and moisture. Cure concrete properly for a minimum of three days in order to develop good durability. In this study mortars with white cement and Portland cement and different w/c ratios were produced and investigated. The mortars produced were then tested for the impacts of alkali silica reaction (ASR), high temperatures, abrasion and acid effect. Results show that less expansion was measured on the mortars using portland cement while the white cement gave the largest expansions (approximate 0.60%).However, there was no significant difference between cements in terms of their acid resistance. The impact of higher temperatures on mortars produced using white cement was less in comparison with normal Portland cement. Durability tests showed that w/c ratio plays an important role. © 2017, Fundatia Serban Solacolu. All rights reserved.Item The Optimization of Calcareous Fly Ash-Added Cement Containing Grinding Aids and Strength-Improving Additives(Hindawi Limited, 2018) Kaplan G.; Yildizel S.A.; Memiş S.; Öztürk A.U.This is an experimental study which explores the physical, mechanical, and economic factors involved in the production of type CEM II A-B/W cement. In this context, 4 cement additives were used in two different dosages (200 and 800 g/t). Class C fly ash was used for composite cement production at ratios of 5%, 20%, and 35%. It was shown that Blaine fineness increases with the increasing fly ash content. The use of fly ash at ratios of 5% and 20% was not found to have any unfavorable effects on the compressive strength at the early days. It is found that the use of additive for improving the early-age strength is preferable when fly ash is used. It is possible to produce Class 52.5 N cement using additives to improve early strength and 20% fly ash. Loss in strength was observed in cement mortars produced using glycol-based grinding aid. Increasing the dosage of chemical additive also led to loss in strength due to nonhomogeneous distribution of hydration products. As a result, grinding fly ash with clinker and the use of cement chemicals contribute to the cement sector in terms of sustainability. It is possible to produce cements with improved mechanical properties especially with the use of 20% fly ash. © 2018 Gökhan Kaplan et al.