Abstract
Consolidation and hydrophobic treatments of historical carvings and
architectural monuments made of stone is a challenging intervention that, in many
cases, is considered irreversible due to the chemical bonds that are created between the
reinforcing material and the substrate. However, these interventions are often
unavoidable, especially when stone structures are at risk of destruction, failure, and
collapse due to aging and weathering. Examination of historical monuments and their
consolidation and hydrophobicity operations needs to be monitored continuously;
otherwise, a deep erosion of layers and loss of cohesion is a risk of complete collapse.
Historical monuments, sculptures, and stone inscriptions are fragile and vulnerable due
to centuries of exposure to harsh weather and open space. Reinforcement of historical
stones requires attention to surface treatments to reduce moisture, prevent biological
damage, and increase mechanical properties. In this research, various challenges related
to historical and cultural monument protection interventions have been addressed.
Several nanoparticles and polymeric materials have been introduced for this purpose.
Organic and inorganic materials such as acrylics, silanes, and nanocomposites play an
essential role in preparing hydrophobic and reinforcing coatings for use in historical
stone artworks. Reinforcement and hydrophobicity operations with silane/siloxane
compounds have been proposed as potential polymeric materials for protective coatings
and limestone layers' stabilizers. Combined silane and siloxane coatings can improve
historical monuments' physical, biological, and mechanical properties against weather
conditions. The results showed that the samples coated with silane/siloxane resins have
appropriate hydrophobic properties. The reason may be that organic groups of
polysiloxanes as hydrophobic agents increase the surface's hydrophobic nature.
Besides, Si-OH silane bonding and the integration effect can be caused by covalent
bonding by mineral surfaces and filling narrow stone surface gaps. Among other
important factors that affect the properties of hydrophobic operations, the presence of
fluorinated functional groups on the composition of the coating and the effect of
hydrophobic properties of additives on stability and weather resistance in harsh
conditions have been discussed. Besides, the use of mineral nanoparticles in the coating
composition is a valuable way to improve the combined properties, self-cleaning, and
anti-microorganism in conservation and protection treatments. Recent scientific
developments also emphasize the need for water-based resins with environmentalfriendly
characteristics.
Keywords: Coating, Consolidation, Hydrophobic, Nanoparticle, Polymer, Stone.