<title>Integration of qualitative and quantitative infrared surveys to study the plaster conditions of Valentino Castle</title>

Abstract

This paper presents the results of a project in which a correlation was made between the results of qualitative and quantitative analyses of the state of plaster on the facade of Valentino Castle in Turin, Italy. The aim of the project was to assess its condition in order to plan restoration work.Surveys (including JR thermographic scanning, knocking tests and surface color inspection) were undertaken over a three years period in different seasons and conditions (shade, direct sunlight, etc.), so that the effects of outside temperature, internal heating and solar radiation could be taken into account. The results were then superimposed so that real defects could be distinguished from apparent ones. An attempt was made to identify a typical thermal trend for each kind of defect.Good correspondence was generally obtained between thermal anomalies revealed by JR surveys and data from the knocking test. However, qualitative analysis was not always adequate to identify the type of damage. More detailed information was obtained from quantitative methods, but the time-consuming analysis involved made it necessary to integrate the two approaches: qualitative methods being used to identify problem areas, then detailed analysis being undertaken with quantitative methods.

Close-Range Sensing and Data Fusion for Built Heritage Inspection and Monitoring—A Review

“…New critical developments in thermal measuring device technology, combined with other advantages stemming from its nondestructive nature, have led to widespread application on structural surveys of monumental and historic architecture [135][136][137][138][139]. Moreover, the applications of passive IRT concerning the investigation of historic buildings include the localization of original and replacement materials [140][141][142], evaluation of the plaster conditions [143][144][145][146], assessment of cracks [137,147,148], characterization of material loss-induced features, and other alterations on architectural surfaces [139,[149][150][151], detection of moisture [152][153][154][155][156], localization of concealed defects and subsurface construction [157][158][159], in addition to evaluation of restoration and consolidation interventions [2,160]. Increased demand is also reported regarding the inspection of masonry arc bridges since their periodical inspection can be difficult due to access restrictions, which necessitates the application of remote sensing techniques [161][162][163].…”

3D Thermal Mapping of Architectural Heritage

“…Over the last years, the sensors used for the documentation and assessment of thermal phenomena have evolved and diversified. Therefore, IRT has been extensively applied regarding cultural heritage for the evaluation of the state-of-preservation of traditional and historical materials and structures [1], the behavior of replacement materials [2], the effectiveness of the cleaning of architectural surfaces, the efficacy of consolidation interventions, the compatibility of masonry restoration interventions by repair mortars [3,4], the extent of plaster detachment and integration [5], the moisture content [6], as well as for the uncovering of hidden features and subsurface construction [7,8]. Thermographic investigations of architectural heritage are often conducted independently from the acquisition of the structure's geometry and examine thermal phenomena on a local scale by acquiring two-dimensional (2D) thermograms.…”

IRT in the investigation of buildings and historic structures

“…There have been many works of conservation interventions or restorations where the use of incompatible materials or treatments accelerated the damage to the authentic historic structure 1,2 . For this reason, the development and use of evaluation techniques for the appropriateness of a conservation treatment is essential.…”

“…In other words, the energy required to raise the temperature of a moist area would be much greater than an area that is unaffected by water. This can be understood from the following equation: (2) where: Q is the absorbed energy (Joules), m is the mass (Kg), Cp is the specific heat capacity (Jkg -1 K -1 ) and ∆T is the change in temperature (K).…”