Natural Stone Weathering and Conservation

Due to the close connections to the "Stone Department" of the Institute for Conservation and Restoration of Applied Arts, materials science work on the subject of stone weathering and conservation is a focal point of our research activities. Apart from accompanying the students during the semester, intermediate diploma and diploma theses, we have been able to demonstrate and expand our expertise in an international framework during the course of several EU-funded research projects spanning several years. We have always endeavored to primarily contribute to these projects through the application of our core competencies: the characterization of structural damage and the evaluation of the efficiency of measures to strengthen weathered natural stone and mortar using light and scanning electron microscopy. Additionally, we have been able to contribute through planning and execution of large laboratory test series such as the testing of thermal aging of stone samples for strengthening, the evaluation of individual petro-physical parameters in the laboratory and the elaboration and execution of scientifically founded methods for the artificial weathering of strengthened stone samples.

The diagnostic evaluation of structural damage caused by the weathering of stone in outdoor areas constitutes considerable challenges for the conservation sciences. Diagnostic methods that are non-destructive or low-destructive and can be applied directly to the object would naturally be preferable, but are limited according to the current state of the art. In most cases the aim is to detect micro-cracks, changes in the pore space, or secondary products that have formed in the uppermost millimeters of the weathered material in rapidly changing characteristics and intensities. This requires the use of tools with a high spatial or depth resolution. Although the taking of representative samples represents a more aggressive investigation, light and scanning electron microscopic analyses of these samples is currently an alternative method for studying the sequence of structural damage inside the stone, which in exchange allows for a diagnosis with micrometer precision. The same applies to the investigation of the active ingredients of strengthening agents in cracks and pores. This is where our studies come in, which, for more than a decade, have made important contributions to large-scale research projects. The analytics mentioned are not only a methodical goal in accordance with the demands of the conservation sciences, but are additionally a means to the end for the testing of both proven and innovative stone preservatives and processes, which can be tailored to the specific requirements of the respective historical material.

We owe a large part of our many years of project activities in this field, which has also led us into the world of nano-materials, to the commitment of our employee Elisabeth Mascha. Among the numerous external institutions we cooperate with closely the most notable are the Research Department of Engineering Geology at the Institute of Geotechnics of the Vienna University of Technology (A. Rohatsch, M. Ban), the Cathedral Construction Office St. Stephan, and the Faculty of Restoration Litomyšl of the University of Pardubice (CZ). Further cooperation partners can be found on the websites of the individual projects.

Project history:

• EU-RP7- NMP-2007-4.0-6 STONECORE – “Stone conservation for the Refurbishment of Buildings” (2008-11). Zur Project Website
• ETC Austria-Czech Republic 2007-2013 NANOLITH – “Historic Stone Monuments of “Leithakalk” (Limestone): Research on New, State-of-the-Art Methods for the Preservation of Art Objects (2013-14)
• EU-H2020-NMP-4.0-6 Nano-Cathedral – “Nanomaterials for Conservation of European Architectural Heritage Developed by Research on Characteristic Lithotypes” (20015-18). Project Website

Relevant Dissertations:

Mag.art. Elisabeth Mascha: Visualization of strengthening agents for porous building materials in restoration. (completion 2019)

Supervision:
ao. Univ.-Prof. Dr. phil. Johannes Weber
o.Univ.-Prof. Dr. Gabriela Krist

Mag.art Marija Milchin: Protection for natural stone in outdoor areas - preventive and invasive measures. Dissertation (initial stage)

Supervision:
ao. Univ.-Prof. Dr. phil. Johannes Weber
o.Univ.-Prof. Dr. Gabriela Krist