Factors influencing salt-induced weathering of building sandstone.

Pombo Fernandez, Susana

Abstract

The role of chemical cleaning in causing salt-induced weathering of building sandstone was investigated by looking at the changes in a series of weathering indicators selected. These were mainly, porosity and pore size distribution changes, chemical composition and colour changes. Laboratory studies involved the use of artificial weathering studies. Samples of Locharbriggs and Crossland Hill sandstones were first studied after partial immersion in salt-contaminated solutions. No temperature variation or humidity cycling was promoted. Samples were then exposed to cycles of humidity and temperature that simulate wet/dry cycles based on field data from a representative Scottish environment. Additional studies involved exposure of samples to SO2 gas and water spray at acid pH. These studies aimed at understanding the effects of environmental factors (relative humidity, temperature, SO2 and pH) which can promote salt- induced weathering of building stone. Weathering studies carried out on chemical cleaned samples have not been reported previously, and therefore represented a novel use of temperature and humidity controlled chambers. The possibility of environmental/climatic influence on the action of salts in sandstone by means of different intensity on dry/wet cycles, salt crystallisation and salt migration was also studied by exposing the samples to four different locations in Scotland (Banff, rural-coastal; Dunkeld, rural-inland; Aberdeen, urban-coastal and Glasgow, urban-inland) after being chemically cleaned. The analysis of the field exposure data involved statistical analysis and especially multivariate methods of the damage salts against the environmental data. In general, the indicators selected showed the following trends independently of having a control (not cleaned) or a chemical cleaned sample: porosity decreased, and most ions presented a similar distribution pattern after field exposure.

Citation

POMBO FERNANDEZ, S. 1999. Factors influencing salt-induced weathering of building sandstone. Robert Gordon University [online], PhD thesis. Available from: https://openair.rgu.ac.uk

• Thesis Type: Thesis
• Deposit Date: Nov 4, 2020
• Publicly Available Date: Nov 4, 2020
• Keywords: Sandstone; Salt weathering; Stonecleaning; Environment; Porosity; Chemical analysis; Colour changes; Building conservation
• Public URL: https://rgu-repository.worktribe.com/output/981845