Non-Destructive Techniques Applied to Monumental Stone Conservation

Abstract

Non-destructive techniques have always been used in the study of built cultural heritage because of the high cultural value of the concerned objects and the need to preserve them as intact as possible. In this chapter, different non-destructive techniques applied to the conservation of historical building are presented. The selected techniques concern the measurement of some physical properties of the building materials measured at the surface: water absorption, permeability, water content, cohesion, hardness and so on; the actual conditions of the building: stress state, deformation, crack growth and so on; and in-depth physical properties: mechanical properties, inner structure of walls, damp location and salt content. Some of these techniques are used for inspection of the building at a given time, whereas others can be applied for long periods of time to investigate the evolution of the building or of one of its parts (e.g., crack propagation) with time. After presenting the physical background of each method, the main objective of this review is to focus on the applications, especially to discuss which information can be supplied and to present published results in each case. Some techniques are very simple and require very inexpensive equipment but others, which are mainly adaptations of field geophysical techniques, use more sophisticated technology and require post-acquisition treatments based on more complex physical principles. Finally, some examples of combinations of different techniques are presented because a unique method cannot provide all the information needed to understand the weathering processes taking place in a building. The final goal of the studies is to contribute to the preservation of the cultural heritage. The choice of the conservation strategies and methods should be based on a deep knowledge of the building, and nondestructive testing is usually the only way to get it.

A laboratory study of Equotip surface hardness measurements on a range of sandstones: What influences the values and what do they mean?

“…The Equotip hardness tester is a versatile, field-portable piece of equipment originally designed for testing metal hardness which has also become popular for non-destructive, rapid assessments of the surface hardness of rocks and building materials (Verwaal and Mulder, 1993;Aoki and Matsukura, 2007;Viles et al, 2011;Menéndez, 2016). Surface hardness measurements are often made as part of geomorphological studies into the degree and rate of rock weathering and stone deterioration (André et al, 2014;Wilhelm et al, 2016a) and assessments of the performance of conservation materials such as consolidants (Perez Ema and Bustamente Montoro, 2013;Zornoza-Indart and Lopez-Arce, 2016).…”

Study of the Behavior of Structural Materials Treated with Bioconsolidant

“…The lime mortar specimens, as well as the various Bateig stone specimens, were subjected to the ultrasonic test [ 40 ]. The ultrasonic tester (Steinkamp BP-5 model) was used to measure the transit time, i.e., the time taken by the ultrasonic pulse to travel the distance from the emitting probe to the receiving probe, passing through the specimen under study.…”

A Geological Perspective on Climate Change and Building Stone Deterioration in London: Implications for Urban Stone-Built Heritage Research and Management

“…In situ, high resolution (up to 600× magnification) and contrasted images can be obtained using a fibre optic microscope. This requires no surface preparation but can be used to assess any preliminary decay based on the information on the surface texture and morphology, as well as evaluation of cleaning and consolidation interventions [94].…”