Pore Structure and Water Transfer in <i>Pietra d’Aspra</i> Limestone: A Neutronographic Study

Neutron radiography (NR) was here applied to study the effects of two different commercially available consolidants on the water absorption properties in a particular type of limestone (biocalcarenite), known as <i>Pietra d’Aspra</i> stone, which is one of the most extensively used lithotypes in Sicilian Baroque buildings. Our attention was mainly focused on the evaluation, using a fast and nondestructive visualization of water motion through capillarity, of the effectiveness of such layers as consolidating agents in view of preserving and maintaining both old and modern structures. The biocalcarenite was treated with nanosilica (Nano Estel^®) and nanolime (CaLoSil^®) by brushing it until full saturation, and then artificially weathered by salt crystallization and temperature/relative humidity jumps. Liquid distribution and height of the water front were monitored as a function of time. Significant differences in the water suction behavior among all the investigated samples were highlighted, which allowed us to gain insight into the coating/substrate interaction mechanisms which regulate the fluid mobility inside the porous network of the limestone.