New study on the Deterioration of volcanic tuﬀ rocks from Armenia: constraints on salt crystallizati
Photo: The first author of the study Mr Christopher Pötzl during a research trip to Armenia.
In the framework of the research an summer school project "Stones in Armenian Architecture", by the Georg-August university of Göttingen (Germany) and the National University of Construction and Architecture Yerevan (Armenia) the first study about the deterioration of volcanic tuff rocks from Armenia could be realized. The project is supported by the Volkswagen Foundation (AZ93919). After a first research trip in 2016 and research work by students and scientists the authors Christopher Pötzl, Siegfried Siegesmund, Jordy Michael Koning, (Georg-August ,University of Göttingen/Germany), Reiner Dormann (Federal Institute for Geosciences and Natural Resources - BGR) and Wanja Wedekind (Applied Conservation Science) now published the article. The study is published in Environmental Earth Sciences (2018) 77:660 https://doi.org/10.1007/s12665-018-7777-8 with the title Deterioration of volcanic tuﬀ rocks from Armenia: constraints on salt crystallization and hydric expansion. The abstract gives an overview:
Volcanic tuﬀs are widely used in the Armenian architecture and represent building stones of the country’s most precious cultural heritage sites. For the very ﬁrst time, extensive investigations regarding their chemical and mineralogical composition as well as the inﬂuence of petrophysical properties on their weathering behavior were realized. Diﬀerent groups of tuﬀ rocks could be identiﬁed, which diﬀer greatly in their chroma, texture, their chemical and mineralogical composition, as well as their weathering behavior. At 30% porosity and 25% micropores, the tuﬀ rocks show a sharp limit of changing water transport and retention behavior. Swellable clay minerals, the amount of micropores and the hygroscopic sorption value show a direct relation with the hydric expansion and proved to be reliable parameters for its estimation. Zeolite minerals proved to drastically increase the sorption values of the tuﬀ rocks and are discussed as a cause for potential disjoining pressure. Furthermore, the application of the salt bursting test by European standard on these glass-rich volcanic tuﬀ rocks is
questioned, due to considerable diﬀerent mineralogy and fabric in comparison to classic ash-rich tuﬀs.