Tailoring alkoxysilanes with poly(ethylene glycol) as potential consolidants for carbonate stones

Despite many existing solutions and the research effort to produce tetraethyl-orthosilicate(TEOS)-based products with improved properties for the consolidation of carbonate stones in built heritage, there are still many open questions. Drawbacks such as the influence of the carbonate media and the tendency of the gel to crack during the drying-shrinking phase are well-known. This work addresses the development of new TEOS-based solutions modified with poly(ethylene glycol) (PEG) as organic modifier and the potential of their application for consolidation of limestone. The results demonstrate reduced cracking tendency in xerogels modified with PEG addition, ability to provide cohesion to calcite powder for a selection of formulations, and enhanced cohesion when applied to stone samples. Therefore, an initial set of products seems to present potential for consolidation of carbonate stones, displaying low degree of incompatibility risks that were initially assessed (e.g. negligible colour alteration, no formation of superficial ‘crust’, low alteration of stone porosity).