Evaluation of commercial consolidating agents on very porous biocalcarenite

Nowadays, the conservation of heritage buildings is an essential and important event. Different kinds of materials are available for restoring both natural and artificial stone substrates, and new commercial products have been proposed in recent years. In the present research work we investigated the effectiveness of an alkylalkoxysilane-based commercial consolidant (named VP5035) with respect to the well known tetraethoxysilane (TEOS, commercially labeled as DN). The two products were evaluated when applied on laboratory specimens of a very porous bio-calcarenite, i.e. Lecce stone (PL). Different experimental techniques were used to investigate the performances of both commercial products. At first, chromatic variation, static contact angle, water capillary absorption, permeability to water vapor were measured in order to evaluate the effects induced by treatments on the stone surface. The properties of treated stone were also investigated by Fourier-Transform InfraRed (FTIR-ATR) and scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM-EDS). Measurements concerning surface cohesion and resistance to weathering effect induced by salt crystallization were performed in order to evaluate the consolidation performances of the two consolidants. These results suggest that the commercial product VP5035, when applied on Lecce stone displays a promising dual consolidating-protective behaviour.