The effects of freeze–thaw (F–T) cycles on the Gödene travertine used in historical structures in Konya (Turkey)

Abstract

Travertine, a building material used around the globe for its decorative and easy-to-be-worked features from past to present, is naturally exposed to the freeze–thaw (F–T) process in cold regions in winters. As a result of this process, building stones deteriorate partially or completely. The greatest factor during the F–T process is the existence of water. The water contained in the body (in discontinuities and pores) of a building stone freezes along with the fall of temperature below 0°C. Following freezing, the volume of water contained in discontinuities and pores increases. New fractures develop on the surfaces of pores as a result of outward pressure due to this increase in volume. As the temperature drops below 0°C, the volume of water increases again, due to freezing. This process repeats itself with the decrease and increase in temperature and causes undesired deteriorations in the bodies of stones.This issue is quite important from the point of view of preservation and restoration of historical buildings, and foreseeing the effects of the F–T process on new buildings to be designed.In this study, the effects of the F–T process on Gödene travertine were investigated. Gödene travertine is a stone that has been widely used in historical buildings in Konya, a city that also covers Çatal Höyük, which is known as one of the oldest human settlements in Anatolia. The stone is still being used in buildings constructed in the region. Fresh travertine stones obtained from the quarry were exposed to freeze and thaw cycles in different numbers. Values of porosity (n), uniaxial compressive strength (σu), point load strength (Is(50)), Brazilian tensile strength (σt), Böhme abrasion loss (BA) and P wave velocity (Vp) were statistically evaluated and thus, the effects of the number of cycles on basic physical and mechanical characteristics of the Gödene stone were investigated. Furthermore, deteriorations that took place in historical structures in the region were case-studied.