## 3 Materials Used for Restoration and Conservation of Masonry Elements
### Restoration/Conservation of Masorry Materials against Abiotic Factors
#### 3.3.3 Consolidation and Protection Agents
Using commercially available silica nanoparticles dispersed in commercial alkoxy silanes and organic fluoropolymer emulsion obtained superhydrophobic and superoleophobic coatings, successfully applied for the protection of masonry (marble, sandstone) and other materials (concrete, paper, silk), proving a good versatility of the method. The use of hydrophobic components (such as calcium stearate or silane/stearate) was also proposed [PERSON] et al. [130] as a viable alternative in order to develop restoration mortars with hydrophobic properties (thus, protection action). The authors introduced the water-repellent admixtures into pozzolana lime-mortar (0.5%-1.5%), obtaining materials with reduced water vapor permeability, without significantly affecting the mechanical properties of the mortar. When developing functional coatings for masonry materials, particular attention should be payed to the possible formation of a coating surface which could seal in potential degradation agents and interfere with normal wet/dry cycle [70; 131]. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Procedure (Effect)** & **Material** & **Characteristics and Application** & **Stone Type** & **Ref.** \\ \hline \multirow{8}{*}{Cleaning} & \(\text{TO}_{2}\) nanoparticles & 18 nm, aqueous solution, applied by spraying & Traverting & [132] \\ \cline{2-5}  & \(\text{TO}_{2}\) nanoparticles & 10-20 nm obtained by sol-gel and hydrothermal method, & & Traverting & [94] \\  & applied by spray coating & & & \\ \cline{2-5}  & \(\text{TiO}_{2}\)/poly(carbonate urethane) & 31 nm, commercially available, aqueous dispersion; with & - & [133] \\  & nanocomposite & associated protective role & & \\ \cline{2-5}  & \(\text{TiO}_{2}\) nanoparticles & Commercially available nanoparticles (25 nm), incorporated in & & Marble, calcarenite & [93] \\  & & different commercial coatings & & \\ \cline{2-5}  & \(\text{TiO}_{2}\) nanoparticles & 5-6 nm, dispersed in water and ethylene glycol, applied by & & Marble, calcarenite & [134] \\  & & brush & & \\ \cline{2-5}  & \(\text{TiO}_{2}\) nanoparticles & Commercially available nanoparticles (30 nm), incorporated in & & \\  & different mortars & & & \\ \cline{2-5}  & \(\text{TiO}_{2}\)—tetrahexosilane- & 25 nm, commercially available, applied by brush & & \\  & polydimethylsiloxane & & & \\ \cline{2-5}  & \(\text{TiO}_{2}\) nanoparticles & 10-40 nm, commercially available, aqueous solution, applied by & & Sandstone, concrete slabs & [137] \\  & & spraying & & \\ \cline{2-5}  & \(\text{TiO}_{2}\) nanoparticles & External layer in a multi-purpose solution, with oxal acid in & & biomicritic limestone, travevette, calcite & [108] \\  & & the interface with environment; surface application, by brush & sandstone, ceramic materials, mortars & [108] \\ \hline \multirow{8}{*}{Consolidation} & \multirow{2}{*}{Different inorganic additives} & Earth of Milos, brick powder, crushed brick, used as pozzolanic & & Mortar & [116] \\  & & additives for line mortars & & \\ \cline{2-5}  & Inorganic additives & Palyorska and metakolain, used as pozzolanic additives for & & Mortar & [117] \\ \cline{2-5}  & \multirow{2}{*}{Organic additive} & Commercial product (consisting of n-heptadecane core and & & \\  & & polymethyl-methacrylate shell, PCM DS 5001 Micronal®), & & Mortar & [118] \\ \cline{2-5}  & & incorporated in line mortar & & \\ \cline{2-5}  & \multirow{2}{*}{Basalt fibers} & Incorporation in different composition for development of & & \\ \cline{2-5}  & & restoration mortars & & \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Materials for the treatment of stones used in the vernacular constructions (references presented in chronological order). \begin{table}
\begin{tabular}{c c c c c} \hline
**Procedure (Effect)** & **Material** & **Characteristics and Application** & **Stone Type** & **Ref.