URBAN STONE DECAY: THE GREAT WEATHERING EXPERIMENT

There is an increasing catalogue of projects and publications in which earth scientists have sought to apply their knowledge of natural weathering to the explanation of building stone decay. Especially through the design and application of weathering simulation experiments. Interestingly, there are relatively few examples where this exchange of expertise has been reciprocated. Yet, students of natural weathering frequently complain that they have too few controls on the processes operating and know little of the stress history of the rocks they study. This, in turn, hinders definitive explanations of, for example, the spatial and temporal variability of weathering rates. This presentation therefore investigates the potential of using the relatively controlled conditions of stone placed in buildings to provide insights into how rocks behave in outcrop. The approach is exemplified through studies of feedback mechanisms that control episodic stone decay and the ‘memory effect’, whereby observed decay is influenced by a stone’s history of exposure and conservation intervention. These studies exploit ‘weathering experiments’ created by architects who, for example, simultaneously expose combinations of stone types to the same environmental conditions, or conveniently align structures of one stone type to allow evaluation of aspect effects.