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Ozguven A.,General Directorate of Mineral Research and Exploration | Ozcelik Y.,Hacettepe University
Engineering Geology | Year: 2014

It is known that fire and high temperatures cause degradation of natural building stones. There are many studies focused on the effect of high temperature on physico-mechanical properties of sandstone and granites while there are a few insufficient studies on limestones and marble. Almost all of the studies performed on limestone and marble are established at temperatures lower than 1000. °C and just focused on investigating some of the physico-mechanical properties of natural building stones and therefore some of the physical and mechanical properties of limestones and marbles exposed up to this temperature are not studied in detail. That condition cannot explain how the properties of marble and limestone change with high temperatures, which are widely used in many areas of our lives as building materials. The aim of this study is to investigate the changing of physico-mechanical properties of natural building materials including limestone and marbles exposed to different temperatures ranging from room temperature up to 1000. °C in the oven. For this purpose, samples were exposed to the heat separately starting from 200. °C, gradually 400, 600, 800 and 1000. °C and then some physico-mechanical properties of them and reference sample at room temperature were determined. The results obtained from the tests were analyzed in detail in terms of criticality of temperature degree, positive or negative effect of temperature rise, reusability of the building stone exposed to heat.As a conclusion of the study, important results are given in many aspects such as, usage areas of fire exposed natural stones, safety precautions at usage areas in addition to gained properties of natural stones due to temperature. © 2014 Elsevier B.V. Source


Ozguven A.,General Directorate of Mineral Research and Exploration | Gunduz L.,Suleyman Demirel University of Turkey
Cement and Concrete Composites | Year: 2012

It is important to know which parameters are effective for the manufacture of expanded clay aggregate and to determine how effective these parameters are on expansion. In this study, expansion tests were conducted by using samples from three separate fields to determine how different parameters influence manufacturing. Clay grain size, pellet size, temperature in the furnace and firing time were selected in the expansion tests as parameters. Their effect on production was evidenced separately. It was found that decreasing the clay size has a positive effect on expansion while a decrease in pellet size has a negative effect on it. Also, temperature in the furnace and the time period during which the clay remains in the furnace are critical values for the resultant aggregate quality. The conditions for optimum manufacturing were explained in detail. © 2012 Elsevier Ltd. All rights reserved. Source


Ozguven A.,General Directorate of Mineral Research and Exploration | Ozcelik Y.,Hacettepe University
Construction and Building Materials | Year: 2013

Under the influence of fire and other high heat sources, a number of changes occur in natural stones. These changes vary according to the values of the temperature exposure. Therefore, this study aims to understand the effect of heat in a fire and high temperatures on some properties of limestone and marble, as they are widely used natural building stones. For this purpose, eight natural stones (four limestone and four marble) of different origins and textural characteristics were exposed to 200, 400, 600, 800 and 1000 °C temperature in the oven. After each exposure, the rock properties were determined and compared with the properties at room temperature. Discoloration and whiteness, polish reception, daily physical change, variation of pH and temperature of the cooling solution were taken into account in the comparison. As a result of this study, the positive and negative aspects of the property changes that occur in natural stones which are exposed to different temperatures are discussed. © 2012 Elsevier Ltd. All rights reserved. Source


Gurboga S.,General Directorate of Mineral Research and Exploration
International Geology Review | Year: 2016

The present-day tectonic framework of Turkey comprises mainly two strike-slip fault systems, namely dextral North Anatolian and sinistral East Anatolian faults. They are considered as the main cause of deformation patterns in Anatolia. These two mega shear systems meet at Kargapazarı village of Karlıova county. The area to the east of the junction has a transpressional tectonic regime between the Eurasian and Arabian plates and is characterized, based on field observation, by a network of faults defining a typical horsetail splay structure. The horsetail splay is interpreted as marking the termination of the North Anatolian Fault System (NAFS), which continues eastward into the Varto Fault Zone (VFZ) and then dies out. The present study reveals that the VFZ is made up of two main parts, namely the principal displacement zone (PDZ) and the transpressional splay zone (TPSZ), both characterized by the right-lateral strike-slip with reverse motion. However, the area to the east of Varto is characterized dominantly by reverse-thrust faults and E–W-trending faults as shown by focal mechanism solutions. The generation of the VFZ as a transpressional termination to the NAFS can be related directly to the block movements of the Eurasian, Anatolian, and Arabian plates. © 2016 Informa UK Limited, trading as Taylor & Francis Group. Source


Karakul H.,General Directorate of Mineral Research and Exploration | Ulusay R.,Hacettepe University | Isik N.S.,Gazi University
International Journal of Rock Mechanics and Mining Sciences | Year: 2010

This study aims to investigate the strength anisotropy associated with discontinuity orientation by performing block punch index (BPI) tests and uniaxial compressive strength (UCS) tests, and to develop some empirical relationships for estimating the BPI and UCS in the strongest direction, and the UCS from the BPI determined at any angle between the loading direction and weakness plane. The experimental results obtained from six rock types show that these rocks fall into the moderate-to-low strength anisotropy classes. The comparison between the observed and predicted UCS values indicated that the prediction performances of the equations developed are quite good. Numerical simulations revealed that numerically estimated BPI values are very close to experimentally determined values for each angle between the loading direction and the weakness planes involved by the BPI specimens. As the angle between the weakness planes and loading increases, plastic zones become wider and unsymmetrical. The results of this study are also applicable to anisotropic rocks outside the strength ranges of the rocks studied by the authors, but their degree of anisotropy should be in the range of low-to-moderate. © 2010 Elsevier Ltd. Source

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