Browsing by Author "Kaplan, G"

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    A STUDY OF SOME DURABILITY PROPERTIES OF MORTARS WITH WHITE CEMENT AND PORTLAND CEMENT
    Öztürk, AU; 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.
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    The Optimization of Calcareous Fly Ash-Added Cement Containing Grinding Aids and Strength-Improving Additives
    Kaplan, G; Yildizel, SA; Memis, S; Öztürk, AU
    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.
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    Cost Optimization of Mortars Containing Different Pigments and Their Freeze-Thaw Resistance Properties
    Yildizel, SA; Kaplan, G; Öztürk, AU
    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.
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    MAJOR CONSTRUCTIONAL DISPUTE CAUSES IN TURKEY
    Yildizel, SA; Dogan, E; Kaplan, G; Ergut, A
    The possibility of construction disputes can be reduced, but they cannot be avoided due to the uncertain and risky nature of the building industry. Conflicts between construction parties often have very unfavourable effects, such as cost increases, poor construction quality and time extension in the schedule. Lots of studies have been carried out in order to try and avoid these disagreements. However, there are no common resolution tools or techniques due to the improving conditions and scope of contracted works. Advanced methods and dispute reasons should be fully monitored and updated for the applicable solutions. This paper discusses the current major constructional dispute reasons in Turkey. The questionnaire method was applied within the scope of this study. The questionnaire documents were randomly distributed to 80 contractors to analyse major dispute reasons in Turkey. Analysis of the questionnaire results indicates that the major current dispute causes are poor quality of performed works, delays in progress payments, inefficient site management, poorly written contracts and design mistakes.
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    Prediction of Skid Resistance Value of Glass Fiber-Reinforced Tiling Materials
    Yildizel, SA; Tuskan, Y; Kaplan, G
    This research focuses on the use of adaptive artificial neural network system for evaluating the skid resistance value (British Pendulum Number; BPN) of the glass fiber-reinforced tiling materials. During the creation of the neural model, four main factors were considered: fiber, calcium carbonate content, sand blasting, and polishing properties of the specimens. The model was trained, tested, and compared with the on-site test results. As per the comparison of the outcomes of the study, the analysis and on-site test results showed that there is a great potential for the prediction of BPN of glass fiber-reinforced tiling materials by using developed neural system.