From the laboratory to the monument.
The group of researchers AMBAR of the Polytechnic University of Cartagena (UPCT) has applied chemical synthesis procedures to preserve the cultural heritage in the doctoral thesis of Juan Antonio Madrid.
In this work, pure calcium hydroxide nanoparticles Ca (OH) 2 have been synthesized that have been applied to consolidate historical materials of the Roman Theater of the city and in the restoration of a modernist building.
"The nanoparticles are previously dispersed in an alcohol that evaporates in just seconds without leaving any residue after being sprayed on the monument.
The size of the nanoparticles is between 10,000-100,000 times smaller than the pores of the stone, which ensures its good penetration at the surface level.
Later, in contact with the environmental CO2, they are transformed into calcium carbonate, introducing a kind of natural cement very similar and compatible with soft sandstones such as Tabaire, used in Cartagena since Roman times, "explains the director of the thesis Marcos Lanzon.
"The objective is to consolidate the historical material without leaving potentially dangerous by-products for the historical substratum treated, being able to apply also to the sculptural or pictorial heritage", adds the person in charge of the research group.
"The most complex was to achieve chemically pure nanoparticles for the first time, because those who only market them do not guarantee their purity", details the new doctor for the Polytechnic of Cartagena.
The laboratory work, in the facilities that the group has in the ELDI and in the Service of Support to Technological Research of the UPCT, have confirmed the consolidation capacity of the particles in stone, adobe and stucco.
Calcium hydroxide nanoparticles were successfully used in the rehabilitation of a modernist building on Calle Santa Florentina in Cartagena and were tested in a fortnight of sandstone ashlars of the Roman Theater of Cartagena to curb the normal aging of this type of materials affecting their durability.
In this case, Ana Martínez Arredondo, an extraordinary prize of her promotion, student of the Master of Architectural Heritage of the UPCT and collaborator of the group AMBAR, has diagnosed and completed the study carried out in the Roman Theater using suspensions of nanoparticles synthesized by the Doctorate Juan Antonio Madrid.
"The Romans, aware of the weaknesses of the sandstone extracted in Canteras, covered the stone with lime stucco," says Lanzón, who also directed the Master's Final Project in Science and Technology of Building in Architecture of Soledad Monaco, also extraordinary prize , during which a technique similar to the stucco was applied to the former Marina Hospital, now home to the School of Industrial Engineering of the UPCT.
Researchers are now exploring the possibility of obtaining both consolidating and superhydrophobic nanoparticles to repel water without impeding the cementing action of the treatment.
The researchers also explore the possibility of obtaining nanoparticles consolidating and superhydrophobic at the same time, to repel water without impeding the cementing action of the treatment.
Source: UPCT