A Systematic Approach to Artificial Preageing of Molasse for Studying Consolidation Efficacy

In the field of historical building materials, experimental studies are necessary to optimise the selection and application of consolidation treatments. This is particularly important since the performance of both newly engineered and reference treatments heavily depends on the substrate and is therefore also difficult to predict. This calls for using pre-aged substrates that mimic the characteristics of the material to be treated on site. However, there are currently no standardised procedures for such pre-ageing, nor is there a clear consensus on the best method for reproducing degradation under laboratory conditions. By systematically experimenting with different aging protocols and analysing results from both macro- and microscopic perspectives, this paper establishes a material science basis for such artificial aging stone. In particular, it focuses on three ageing methods for clay-bearing sandstone, how these method affected the properties of the stones and their relevance for studying consolidants. Acid treatment effectively increases decohesion and porosity, simulating decay that typically requires consolidation. However, changes in mechanical properties suggest that the swelling pressure remains unchanged, offering insights into the effectiveness of ethyl silicates on molasse sandstones, whether pre-aged or not.