FRACTURE DYNAMICS AND THE DETERIORATION AND CONSERVATION OF SANDSTONE HERITAGE

Many of the world’s greatest built heritage sites, as well as numerous important geoheritage sites, are made of sandstone. Internationally renowned sites such as the rock-hewn temples at Petra in Jordan, as well as nationally important sites such as Kenilworth Castle in England, and North Grotto Temple, Qingyang in China are carved in, or constructed from sandstone, and experience many deterioration problems. Despite decades of research on the nature and causes of sandstone weathering many unanswered questions remain about how such heritage deteriorates. In particular, there is still lack of knowledge about what controls the observed patterns of weathering – with stress and moisture dynamics likely to be particularly important. As a result, there are still many uncertainties about how best to conserve valuable sandstone heritage in the face of changing environmental conditions. This paper will consider an under-studied factor in the deterioration of sandstone heritage, i.e. the nature and dynamics of fractures across multiple scales. Analysis will be based on a combination of review of previous research and observations from current projects in England, Jordan and China. The paper will conclude that improved understanding of fracture dynamics is a necessary element to successful treatment and management of sandstone deterioration and the conservation of nationally and internationally important heritage over centuries to come. It will also emphasise the need for enhanced consideration of the links between fracture dynamics, moisture dynamics and biological weathering.