Evaluación del tratamiento de consolidación de dolomías mediante nanopartículas de hidróxido de calcio en condiciones de alta humedad relativa

Abstract

En este artículo se presentan los resultados del tratamiento aplicado a muestras de piedra dolomía mediante una solución coloidal isopropílica basada en nanopartículas de hidróxido de calcio en una concentración de 2,0g/l. El proceso de consolidación de la piedra ha sido monitoreado antes y después de su aplicación a los 28 días de estar expuesta a una atmósfera del 75% de humedad relativa. Se ha realizado un estudio morfológico y estructural del consolidante confirmándose el proceso de carbonatación. Los resultados de difracción de rayos X, microscopía electrónica (TEM y ESEM) y difracción de electrones realizados al producto consolidante han confirmado la transformación de la fase portlandita a los polimorfos de carbonato de calcio de tipo calcita, aragonito y vaterita. Los ensayos petrofísicos realizados a la piedra antes y después de su aplicación, han demostrado que se produce una mejora de las propiedades físicas e hídricas indicado por el aumento tanto en la velocidad de propagación de ultrasonidos como en la densidad del material y una disminución de su coeficiente capilar, así como de la porosidad abierta sin producirse modificaciones significativas en el color y el brillo. La aplicación del tratamiento de consolidación propuesto, con este tipo de soluciones coloidales de nanopartículas, es un método natural y compatible con las características petrológicas del sustrato, sin generar daños secundarios sobre la piedra, resultando un método eficaz para la mejora de la durabilidad de rocas carbonáticas. Palabras clave: Consolidación, piedra, polimorfos de carbonato de calcio, nanopartículas de hidróxido cálcico, humedad relativa. Evaluation of a consolidation treatment in dolostones by mean of calcium hydroxide nanoparticles in high relative humidity conditionsIn this article, the results of a treatment applied to dolomitic stones using an isopropyl colloidal solution based on calcium hydroxide nanoparticles with a concentration of 2.0g/l are presented. The consolidation process in the stone has been checked before and after 28 days of exposure to 75% relative humidity. Morphologic and structural studies of the consolidating product confirmed the carbonation process. X ray diffraction, electron microscopy (TEM and ESEM), and electron diffraction carried out on the consolidating product have confirmed the transformation of portlandite phase to calcium carbonate polymorphs, calcite, aragonite and vaterite. Petrophysical tests performed on the stone before and after the application of the product have shown the improvement in the physical and hydrical properties due to the increase in the ultrasound velocity and density of the material, and a decrease in the capillarity coefficient and open porosity without significant changes in colour and brightness. The application of the consolidating product in the proposed experimental conditions is a natural method, compatible with the petrological characteristics of the substrate, without secondary damages on the stone, being an effective method to improve the durabili...

Nanolimes doped with quantum dots for stone consolidation assessment

“…The Ca(OH) 2 nanoparticles of Nanorestore are hexagonal portlandite platelets with an average size of less than 100 nm, as determined by TEM [37,38]. Additionally, the ZnO QDs are spherical particles with an average size estimated at 7.7±1.4 nm by electron microscopy, which is consistent with the size of 8 nm described by Patra et al [25].…”

Nucleation of CaCO3 polymorphs from a colloidal alcoholic solution of Ca(OH)2 nanocrystals exposed to low humidity conditions

“…The use of Ca(OH) 2 nanoparticles has become an alternative to improve the consolidation of cultural heritage carbonate rocks [14], [15], [16], [17]. However, considering that the microstructural characteristics of nanoparticles and their stability may differ depending on the synthesis conditions, even from a same colloidal method, giving rise to differences in the nucleation rate, it is necessary to conduct a complete study of crystalline nanoparticles under external agents such as relative humidity and time of exposure, including their phase transformations and morphological changes.…”

Nanoparticles Applied to Stone Buildings

“…Despite their use in numerous tests on masonries (Gomez-Vilalba et al 2011;Baglioni et al 2014) and the good results achieved as pre-consolidating material (Rodriguez-Navarro, Suzuki, and Ruiz-Agudo 2013; G. Borsoi et al 2015), their effectiveness is reduced when in-depth consolidation is required (Giovanni Borsoi et al 2017). This is due to the migration of the nanoparticles back to the surface of the treated material during the solvent evaporation process (G. Borsoi et al 2015;Giovanni Borsoi et al 2016;Costa and Rodrigues 2013;Taglieri et al 2018), which can sometimes cause the appearance of whitish veils on the surface (van Hees, Veiga, and Slížková 2017; Jang and Matero 2018).…”