LAUSR

Abstract Conservation methods on buildings and monuments made out of natural stone aim on preventing weathering processes, reducing their impact on site and consequently improving the long-term durability of building stones. For this purpose, nowadays particularly organosilicon compounds are used for the application on natural stones. In this study, single-sided NMR has been used to non-destructively detect the long-term efficiency of hydrophobing agents (silanes, siloxanes and silicone resins) applied on different porous natural stones (Baumberger and Obernkirchener Sandstone), which were naturally weathered for over 24 years on different sites in Germany. An evaluation system is presented, based on non-destructive NMR measurements, to assess the hydrophobic properties and the long-term stability of the treated stone surfaces. It could be shown, that the mineralogical composition as well as the type of hydrophobing agent and its active ingredient content have a significant influence on the long-term hydrophobic effect.