NaCl-related weathering of stone: the importance of kinetics and salt mixtures in environmental risk assessment

Heritage Science

Tim De Kock¹  Michael Steiger²  Veerle Cnudde³  Scott Allan Orr⁴  Hilde De Clercq⁵  Sebastiaan Godts⁶  Julie Desarnaud⁷  Katrin Wilhelm⁸ 

[1] Antwerp Cultural Heritage Sciences, ARCHES, University of Antwerp, Mutsaardstraat 31, 2000, Antwerp, Belgium;Department of Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146, Hamburg, Germany;Department of Geology, PProGRess, Ghent University, Campus Sterre, Building S8, Krijgslaan 281, 9000, Ghent, Belgium;Department of Earth Sciences, Utrecht University, Heidelberglaan 8, 3584 CS, Utrecht, The Netherlands;Institute for Sustainable Heritage, University College London, Central House, 14 Upper Woburn Pl, WC1H 0NN, London, UK;Monuments Lab, Royal Institute for Cultural Heritage (KIK-IRPA), Jubelpark 1, 1000, Brussels, Belgium;Monuments Lab, Royal Institute for Cultural Heritage (KIK-IRPA), Jubelpark 1, 1000, Brussels, Belgium;Antwerp Cultural Heritage Sciences, ARCHES, University of Antwerp, Mutsaardstraat 31, 2000, Antwerp, Belgium;Department of Geology, PProGRess, Ghent University, Campus Sterre, Building S8, Krijgslaan 281, 9000, Ghent, Belgium;Monuments Lab, Royal Institute for Cultural Heritage (KIK-IRPA), Jubelpark 1, 1000, Brussels, Belgium;Renovation & Heritage Lab, Belgian Building Research Institute, Lombardstraat 42, 1000, Brussels, Belgium;School of Geography and the Environment, University of Oxford, South Parks Road, OX1 3QY, Oxford, UK;

关键词: Sodium chloride;    Salt mixture;    Weathering;    Crystallization;    Porous materials;    Damage prediction;    Built heritage;   

DOI  :  10.1186/s40494-021-00514-3

来源: Springer

【 摘 要 】

Salt weathering is one of the most important causes of deterioration in the built environment. Two crucial aspects need further investigation to understand the processes and find suitable measures: the impact of different climatic environments and the properties of salt mixture crystallization. We demonstrate the importance of kinetics in quantifying crystallization and dissolution cycles by combining droplet and capillary laboratory experiments with climate data analysis. The results proved that dissolution times for pure NaCl are typically slower than crystallization, while thermodynamic modelling showed a lower RHeq of NaCl (65.5%) in a salt mixture (commonly found in the built heritage) compared to its RHeq as a single salt (75.5%). Following the results, a minimum time of 30 min is considered for dissolution and the two main RHeq thresholds could be applied to climate data analysis. The predicted number of dissolution/crystallization cycles was significantly dependent on the measurement frequency (or equivalent averaging period) of the climatic data. An analysis of corresponding rural and urban climate demonstrated the impact of spatial phenomena (such as the urban heat island) on the predicted frequency cycles. The findings are fundamental to improve appropriate timescale windows that can be applied to climate data and to illustrate a methodology to quantify salt crystallization cycles in realistic environments as a risk assessment procedure. The results are the basis for future work to improve the accuracy of salt risk assessment by including the kinetics of salt mixtures.

【 授权许可】

CC BY