Study of calcium alkoxides as new conservation product for consolidation of historical limestone

The combined action of several physical, chemical and biological factors cause the weathering of stone widely employed in the field of Cultural Heritage. These deterioration processes were well studied and the results have promoted the research and the development of novel types of consolidation treatments to overcome the limitations of traditional ones and to meet the requirements of the historic building substrates. During the collaborative project NANOMATCH [1], different consolidating agents for carbonate supports, as alkaline alkoxides, were synthesized and applied. In particular, calcium alkoxides are metallorganic compounds that, dissolved in an organic solvent, penetrate within the porous substrate and, reacting with moisture and carbon dioxide of the atmosphere, form a calcium carbonate coating on the pore walls [2]. In this study, calcium ethoxide with formula Ca(OEt)2, is characterized, tested and applied on carbonate stone with different porosity, properly selected among those widely employed in Italian Cultural Heritage. Its performance as stone consolidant product was investigated and compared with that of a commercial one, the nanolime Calosil E50. The kinetic of carbonation process of Ca(OEt)2 was evaluated with ?FT-IR and, to understand how the humidity can affect the final product, XRD was used. Preliminary results of the performance of this consolidating treatment applied on carbonate stones regarding the changing in mechanical characteristics- drilling resistance, ultrasonic velocity- and the observation of the coating- photocolorimetric measurements- are here reported and discussed.