The fluorescence emitted by tiny quantum zinc oxide particles can be used to observe how certain substances used in the restoration of historic buildings penetrate. Researchers at Pablo de Olavide University verified this with samples collected in an old quarry in Cadiz, the stone used to build the city hall and Seville Cathedral.
One of the main problems in protecting historical buildings is to lose the cohesion of their building materials.In order to give them greater resistance, the repairer has to use some substances Consolidator, Such as that Lime (calcium hydroxide)Because of its outstanding durability and high compatibility with stone substrates, it has been used since ancient times.
Now from Pablo de Olavide UniversityIn Seville, some patents have been developed and applied for Calcium hydroxide nanoparticles Doping Quantum dots In accordance with the recommendations for consolidating and restoring historical heritage, they can more effectively act as mergers and distinguish the restored materials from the original materials.The details are published in the magazine Construction and building materials.
“The tiny quantum dots smaller than 10 nanometers are made of Zinc oxide He explained that they are semiconductors and therefore give them very interesting properties (due to quantum mechanics, they are different from the properties of larger particles), such as fluorescence, which is what we use. Javier Becerra, One of the authors.
He added: “Because of the fluorescent effect of these quantum dots, we can evaluate the applicability of the therapy to specific monuments. We only need to irradiate a portion of the material with ultraviolet light to determine the depth of penetration of the consolidation agent.”
Calcium hydroxide nanoparticles doped with zinc oxide quantum dots (tiny white spherical). When processing limestone specimens with this material, ultraviolet rays can detect the possibility of the treatment agent (slightly yellow) penetrating the stone. On the right is Seville City Hall. /José María Martín/Javier Becerra
In addition, the product that the author immersed in Nano repair UVDue to the presence of lime nanoparticles, it itself acts as a consolidation agent. Consolidation is a process of increasing the cohesion of materials, strengthening and hardening parts that have suffered certain deterioration. This situation often occurs in buildings that have been hundreds of years old.
Historical quarry sample
Researchers have successfully applied their technology to samples collected from historic quarries in Puerto de Santa Maria and Espera (Cadiz). These iconic monuments can be constructed from these rocks. Seville Cathedral, The World Cultural Heritage since 1987 or the city council of the city.
Becerra said: “In the laboratory, we have obtained an approximate method of applying it to the monument’s treatment in a practical way.” Becerra and other members of the team are also currently working on the archaeological site from Italic ÿ Medina Azahara.
Javier Becerra, Pilar Ortiz, José María Martín, Ana Paula Zaderenko. “Construction and building materials“. Construction and building materials 199, 2019.´