2026-09-05T21:27:23Zhttps://gredos.usal.es/oai/request

oai:gredos.usal.es:10366/1554442025-04-30T20:22:59Zcom_10366_4450com_10366_4395com_10366_3946com_10366_3823col_10366_4451

García Talegón, Jacinta Iñigo, Adolfo Carlos Sepúlveda Correa, Rosa Amanda Azofra Agustín, Eduardo 2024-02-07T08:20:48Z 2024-02-07T08:20:48Z 2022 García-Talegón, J.; Iñigo, A.C.; Sepúlveda, R.; Azofra, E. Effect of Artificial Freeze/Thaw and Thermal Shock Ageing, Combined or Not with Salt Crystallisation on the Colour of Zamora Building Stones (Spain). ChemEngineering 2022, 6, 61. https://doi.org/10.3390/chemengineering6040061 http://hdl.handle.net/10366/155444 10.3390/chemengineering6040061 2305-7084 [En] After subjecting Zamora building stones to accelerated ageing tests, colour changes were studied, namely: (a) freezing/thawing and thermal shock (gelifraction and thermoclasty), and (b) combination of freezing/thawing plus thermal shock and salt crystallisation (sulphates or phosphates) (gelifraction, thermoclasty and haloclasty). Zamora building stones are silicified conglomerates (silcretes) from the Cretaceous that show marked colour changes due to the remobilisation of iron oxyhydroxides. In this work, four varieties were: white stone; ochreous stone; white and red stone; and purple stone Their micromorphological characterization (skeleton, weathering plasma and porosity/cutan) is formed of grains and fragments of quartz and quartzite as well as by accesory minerals muscovite and feldspar (more or less altered), and some opaque. Quartz, feldspar and illite/mica were part of the skeleton; kaolinite, iron oxyhydroxides, and CT opal were part of the weathering plasma or cutans; their porosity were 11.7–8.7%. Their chromatic data have been statistically analysed (MANOVA-Biplot). They showed higher variations in DE*, DL*, Da* and Db*on combined freezing/thawing plus thermal shock and sulphates crystallisation leading to rapid alteration of the building stones. Chromatic differences between the other two artificial ageing tests were less evident and were not detected in all samples. The global effect of ageing on the Zamora building stones darkened them and reduced their yellowing. The ochreous stone suffered the least variation and the purple stone the most. This study of the colour by statistical analyse may be of interest for the evaluation and monitoring of stone decay, which is an inexpensive, simple, easy and non-destructive technique. application/pdf spa MDPI Attribution-NonCommercial-NoDerivatives 4.0 Internacional http://creativecommons.org/licenses/by-nc-nd/4.0/ info:eu-repo/semantics/openAccess Piedras (edificaciones) Conglomerados silicified conglomerates artificial ageing test building stones 3310.04 Ingeniería de Mantenimiento 6203.05 Estética de las Bellas Artes Effect of Artificial Freeze/Thaw and Thermal Shock Ageing, Combined or Not with Salt Crystallisation on the Colour of Zamora Building Stones (Spain) info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion https://www.mdpi.com/2305-7084/6/4/61 ChemEngineering 6 4 61