Different Mediterranean Basin limestones, like Calcário Ançã (Portugal), Calcário Lioz (Portugal), Piedra San Cristobal (Spain), Piedra Escúzar (Spain) and Pietra di Lecce (Italy), have been widely used as building materials in the European architecture. The aim of this study was focused on biodeterioration, mainly on evaluation of the primary bioreceptivity of those materials. A set of samples was inoculated with a cultured photosynthetic biofilm under laboratory conditions. Several assessment tools were applied to monitor the colonization overtime of the different lithotypes. After 3 months of incubation the colonization occurred endolithically in some lithotypes, namely Piedra San Cristobal and Piedra Escúzar . Spectrophotometric determination of chlorophyll a was a useful analytical technique to achieve the total amount of photosynthetic biomass on rock substrates, demonstrating that Piedra Escúzar and Calcário Lioz were the highest and lowest bioreceptive lithotypes, respectively. Microscopic and image analyses were essential to understand the stone colonization process and its pattern of distribution. Physical stone parameters and exposure conditions were shown to play an important role in the establishment and development of photosynthetic colonization.

Calcarenite stone samples from a historic building (Bizerte, Tunisia) were collected and treated under different environmental conditions with several consolidating products: alkoxysilane (ethyl silicate), a surfactant-templated novel sol–gel, Ca(OH)₂, and SiO₂ nanoparticles. These were subjected to marine aerosol accelerated aging cycles and studied by several non-destructive tests and techniques to assess the stability of the products. Results show that weathering caused by salt crystallization is not inhibited but it is slowed down due to the enhancement of superficial mechanical properties (surface cohesion and micro-hardness) achieved after one month of treatments application. A high or low relative humidity of the consolidation environment significantly affects the final mechanical and aesthetical physical properties and therefore conditions the durability of the treated substrates, even producing higher damage than observed in the blank specimens, depending on the product.

Seven silicate rocks used as ornamental stones and having different surface finishing were submitted to salt fog atmospheres in order to compare different susceptibilities to alteration. Polished, honed, hammered and flamed finishing types were tested. Rocks come from Portugal, Brazil and Angola and are widely commercialized. Samples covered quartz rich rocks, silica saturated and undersaturated rocks, mono and plurimineralic rocks, coarse and fine grained rocks. Mineral composition, texture and open porosity showed to be important parameters which determine mass loss among samples, but the finishing type was very effective within samples. Mass loss and porosity increase are higher on hammered samples, contrasted with the lowest loss values on polished samples. The effect of surface hydrophobicity and roughness on the samples having polished finishing was also analysed by atomic force microscopy (AFM) and water contact angle (WCA), indicating that texture and mineral diversity influence the hydrophobic character of the rock surfaces.