Diagnosing decay: the value of medical analogy in understanding the weathering of building stones

Abstract

This paper represents the first element of the introduction to this volume, and as such investigates its principal underlying rationale; namely the importance of accurate diagnosis of stone decay in the formulation of effective conservation strategies. It does this by exploring ways in which perceived similarities between stone decay and human disease have influenced attitudes towards conservation, and how refinements within medical diagnostic strategies can inform future condition assessments of building stones. In doing so, it identifies the importance of looking beyond obvious symptoms to the isolation of the fundamental causes of decay and the factors that control them. These controls are strongly conditioned by accumulated stresses within the stonework. In many buildings these are the product of a complex history involving exposure to a variety of environmental conditions and successive human intervention. Only by understanding these memory effects is it possible to explain current decay phenomena, attempt any prediction of future behaviour or recommend appropriate intervention. The concept of appropriateness is further developed through an examination of the TNM (Tumours, Nodes and Metastases) Staging System for cancer diagnosis. This holistic scheme embodies a progressive approach to diagnosis that begins with a clinical assessment based on how the patient presents, and leads on to more detailed pathological investigations involving sampling, testing and analysis. The scheme also requires an assessment of the certainty of the diagnosis and proposed treatments must be viewed in terms of a cost benefit analysis. A modified version of this staging system has already been developed for use in the physical assessment of buildings. It is suggested that the next stage in its development, and that of any other condition assessment procedure that deals solely with the fabric of a building, is the inclusion of a value-based appraisal of its cultural significance.The decay of building stones is often compared to the effects of an illness -most commonly a cancer -undermining the health of a building and eventually leading to its demise. This analogy has the value of all anthropomorphic comparisons, in that it allows the lay observer to place complex issues within a conceptual framework that relates to their own experience. It also carries with it an assumption that stone ages and has a lifespan that can be drastically shortened by illness. Obviously, there are dangers in pursuing this strategy too far and many risks in imbuing inanimate objects with the capability and desire to shape their own future. However, there remain potentially rewarding avenues along which the medical analogy can be followed that stop short of an invocation of human motivations behind the operation of stone decay systems. Most important is the opportunity it provides for exploring and exploiting underlying strategies developed for the characterization, classification and treatment of disease. The most obvious route is through the ad...

Pravčice Rock Arch (Bohemian Switzerland National Park, Czech Republic) deterioration due to natural and anthropogenic weathering

“…A correct interpretation of the causes of weathering/decay thus makes up the first step toward effective protection of natural and/or historical monuments (Buzek and Šrámek 1985;Smith et al 1992;Winkler 1997;Klemm and Siedel 2002;Török 2003Török , 2008Přikryl et al 2004;Török and Rozgonyi 2004;Smith and Přikryl 2007;Přikryl 2007).…”

Geomaterials in construction and their sustainability: understanding their role in modern society

“…Mitigation of decay includes understanding the mechanisms of decay/weathering (Fig. 6), prevention of the causes of decay, the search for efficient materials to be used in conservation and finding the correct approaches to restoration (Přikryl 2007;Smith & Přikryl 2007).…”

“…Worldwide interest in traditional construction materials has significantly increased during past decades, as reflected by numerous recent textbooks, specialized volumes and conferences focusing on specific materials and/or processes affecting heritage structures (Prentice 1990;Winkler 1994;McNally 1998;Přikryl & Viles 2002;Siegesmund et al 2002;Lorenz & Gwosdz 2003;Přikryl & Siegl 2004;Přikryl & Smith 2007;Boştenaru Dan et al 2010;Přikryl & Török 2010;Smith et al 2010;Török & Přikryl 2010;Cassar et al 2014;Pereira et al 2015).…”

Exploitation of inherited weakness in fire-damaged building sandstone: the ‘fatiguing’ of ‘shocked’ stone

“…Fire damage is also a concern in the preservation of rock art (Tratebas et al, 2004), where irreplaceable works of ancient art are destroyed by fire each year. With this threat to cultural heritage ever present, practical research is needed to better understand the complex problem of fire damage to stone, and, in the important context of complex stress histories (McCabe, 2007;Smith and Prikryl, 2007), how the stress legacy inherited from fire can be exploited by subsequent background environmental weathering processes. This paper explores the supposition that stone response to stress is invariable cumulative, and the immediate impact of a fire event will depend upon previous stress history, and will in turn determine response to any subsequent stresses.…”