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    Durability assessment of the basalts used in the Diyarbakr City Walls, Turkey
    (Springer, 2019) Dursun, Felat; Topal, Tamer
    The Diyarbakr City Walls (DCW), which were recently added to UNESCO's World Heritage List, are among the largest and one of the most impressive monuments from ancient times. The history of the DCW stretches back more than 4000 years, therefore making the extant City Walls a combination and reflection of influences of the various civilizations that settled in the region. Basalts having such different textural properties as massive and vesicular were employed as the principal material in the construction of the DCW. Like many other historical structures, the DCW are suffering from stone deterioration. A large variety of weathering forms can be observed on the basalts used in different sections of the DCW. The behavior of the basalt under different cyclic environmental conditions is not known. In this study, deterioration mechanisms of the basalts were investigated with field and laboratory studies. It is found that iddingsite is a common weathering product developed through the crystal boundaries of olivine. Accelerated weathering tests show that salt crystallization is the most effective deterioration mechanism. The field and laboratory studies indicate that both massive and vesicular basalts are durable; however, the massive basalts are more durable than the vesicular ones. It is also observed that although chemical processes slightly trigger the deterioration mechanisms of the rocks, most of the weathering forms on the DCW are controlled by the physical factors affecting the parameters of the basalts such as porosity, water absorption and uniaxial compressive strength.
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    The impact of cyclic loads on physicomechanical properties of the massive and vesicular basalts
    (IOP Publishing Ltd, 2020) Dursun, Felat; Topal, Tamer
    Stone monuments are the most visible and essential structures of our cultural heritage; however, many of the historical structures around the world are now suffering from stone deterioration. Diyarbakır City Walls, which were acknowledged the status of World Heritage Site by UNESCO, are among the most extensive surviving structures from ancient times. The City Walls have also some deterioration related problems. Basalts having such different textural properties as massive and vesicular were employed as the principal material in the construction of the Diyarbakır City Walls. Weathering is strongly related to the climatic and environmental conditions of the site. In order to evaluate the physical deterioration, environmental conditions were artificially simulated in accelerated weathering tests such as wetting-drying, freezing-thawing, and salt crystallization. For this purpose, 180 massive and vesicular basalt samples were prepared. The effects of these tests were evaluated by visual examination, weight loss, effective porosity, dry and saturated unit weights, water absorptions under atmospheric and vacuum pressure, sonic velocity and uniaxial compressive strength. It is found that the salt crystallization is the most effective accelerated weathering test deteriorating the basalt samples most aggressively. © 2020 Institute of Physics Publishing. All rights reserved.