Controls on permeability: implications for stone weathering
Published:January 01, 2007
In the light of a well-researched relationship between rock properties and susceptibility of stone to weathering, the role of permeability in weathering is examined. A review of weathering studies indicates the varied use and nature of porosity data, but the paucity of permeability studies in weathering trials. Key factors that control porosity and permeability, depositional characteristics and diagenetic processes are discussed and investigated, with a view to discussing the implications for stone weathering. Results from experimental studies on a range of rock types comprising sandstone, limestone and granite are presented. The relevance of permeability measurement is explored in terms of spatial mapping and quantitative assessment of the deterioration of natural building stone. Increased knowledge and appreciation of the inherited characteristics of a rock is demonstrated to provide valuable insight and a greater understanding of how natural stone heterogeneity is accentuated and exploited by weathering and continued exposure to moisture and salts. Mapping the spatial distribution of permeability provides greater insight into the extent of variability in stone deterioration and presents the possibility of monitoring and predicting the hydraulic properties of stone and how these are modified by weathering processes.
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Building Stone Decay: From Diagnosis to Conservation
Stone buildings and monuments from the cultural centres of many of the world's urban areas. Frequently these areas are prone to high levels of atmospheric pollution that promote a variety of aggressive stone decay processes. Because of this, stone decay is now widely recognized as a severe threat to much of our cultural heritage. If this threat is to be successfully addressed it is essential that the symptoms of decay are clearly identified, that appropriate stone properties are accurately characterized and that decay processes are precisely identified. It is undoubtedly the case that successful conservation has to be underpinned by a comprehensive understanding of the causes of decay and the factors that control them. The accomplishment of these demanding goals requires an interdisciplinary approach based on co-operation between geologists, environmental scientists, chemists, material scientists, civil engineers, restorers and architects. In pursuit of this collaboration, this volume aims to strengthen the knowledge base dealing with the causes, consequences, prevention and solution of stone decay problems.