On the use of confocal microscopy for calculating the surface microroughness and the respective hydrophobic properties of marble specimens

Abstract

A building material's surface properties play an important role on its corrosion, mainly due to its interaction with water. Water adheres to a surface and, thus, damages it, to an extent depending on the nature of the material, as well as its surface roughness and porosity. In this study, we focus on marble (a widely used material both in cultural heritage and in modern structures) samples with different surface roughness. The surface roughness at the microscale was calculated using confocal microscopy, and the water contact angle was measured before and after the application of a protective film, in order to study the way inherent roughness affects or even defines hydrophobicity or water-repellency. There seems to be an effect of the inherent marble surface roughness on the quality of waterproofing achieved, which has been qualitatively as well as quantitatively modeled through a simple relation. Such a model can possibly provide means for choosing the most effective coating for the marble surface at hand, thus leading to a more effective corrosion protection.