Methods employed for surveying buildings for condition have traditionally been reliant upon visual assessment and manual recording. Survey of traditional masonry also ostensibly conforms to this approach but, due to the sheer volume of masonry units composing walls, it is often prohibitively time consuming, exceptionally complex and ultimately costly. Notable features of such survey work for ashlar stone types require each stone to be labelled and overlaid with information relative to condition. Further hindering these already costly operations, it has been shown that the accuracy of reporting, including labelling the manifestation of defects and defect diagnosis, is subjective, depending upon the expertise and experience of those evaluating the fabric. Moving beyond these preliminary survey and reporting stages, this situation gives rise to variable repair and maintenance strategies that can have significant cost implications and can debase fundamental conservation activities. The development of digital technologies, such as terrestrial laser scanning, and advancements in novel computer vision statistical techniques can help produce accurate representation of buildings that can be subsequently rapidly processed, achieving many tangible survey functions with greater inherent objectivity. In this paper, an innovative strategy for automatic detection and classification of defects in digitised ashlar masonry walling is presented. The classification method is based on the use of supervised machine learning algorithms, assisted by surveyors' strategies and expertise to identify defective individual masonry units, through to broader global patterns for groups of stones. The proposed approach has been tested on the main façade of the Chapel Royal in Stirling Castle (Scotland), demonstrating its potential for ashlar masonry forms of wall construction. It is important to recognise that the findings are not limited to this culturally significant building and will be of high value to almost innumerable ashlar-built structures worldwide. The research ultimately attempts to reduce the degree of subjectivity in classifying defects, on a scale and rapidity hitherto beyond traditional project cost constraints. Importantly, it is recognised that through automation more effective utilisation of resources that would have been traditionally spent on survey can be redeployed to support fabric intervention or routine maintenance operations.

Lede stone is an important historical stone in Belgium, with many ceased and disappeared historical quarries. Owing to its geological nature, this stone exhibits considerable variation in petrophysical properties. Three macroscopical different facies from the solely remaining quarry area in Balegem (Belgium) were profoundly characterized for their pore network properties and petrophysical properties. The pore network was exhaustively studied combining water imbibition under vacuum, mercury intrusion porosimetry and X-ray computed microtomography. The three facies not only have a strong difference in total porosity, but also differ in terms of pore connectivity and pore size distribution, linked to the variability in microfacies. This has profound implications on the water transfer properties such as atmospheric water absorption, capillary water absorption, omnidirectional drying and water vapor resistance. The petrophysical behavior is illustrated with a salt ageing test. The results can be used for restoration and conservation of Lede stone in the built cultural heritage.

The Pays re´mois in the eastern Paris Basin is an administrative area of 1394 km2; in the surroundings of Reims (France). Two main geological substrata are separated by the Iˆle-de-France cuesta: the Tertiary substratum in the western part is composed of various types of geomaterials (clay, sandstone, limestone, burrstone), whereas the substratum in the eastern part is composed only of Cretaceous Chalk. A field survey in each commune of the Pays re´moisidentified 26 building materials documented in a Geographic Information System database (GIS-database) that includes information about them (lithology, petrographical and petrophysical data, weathering) and the corresponding buildings (e.g. town, georeferenced data, building type, position on the fac¸ade). The spatial analysis of the building materials’ distribution (Standard Deviational Ellipse) with GIS identifies their uses and the criteria established for the selection of the materials: availability, efficiency, workability and durability. Some lithologies were preferred for particular buildings or selected for their efficiency in specific positions. The study also defines the relation between the stones’ origin (local and non-local stones) and their application. This database is useful to establish stone replacement strategies in the Pays re´mois

Reims Cathedral is a major monument in the NE of France originally built with local Lutetian limestone. The recent closure of the last quarries has made restoration using the same stone more complicated. The restoration stones used currently are Lutetian limestones from the centre of the Paris Basin (Saint-Pierre-Aigle and Saint-Maximin stones). Mapping of the Cathedral's façades confirmed the data from ancient manuscripts: Courville stone was the original building stone, but several other local stones from various quarries and beds were also used. As a follow-up to this mapping, Lutetian limestones from five disused quarries were sampled for petrophysical characterization tests: thin section analyses, porosimetry, capillary and drying kinetics. The petrophysical properties of the limestones showed differences between the two main local stone types (Ditrupa limestone and miliolids limestone) and also between the quarries. This study addresses the difficulty of selecting new stone for restoration. Should ancient quarries be re-opened? If so, which ones?

Les carrières souterraines sont de remarquables sites d'observation de la karstification des massifs calcaires. Les plateaux lutétiens semblent très peu karstifiés comparés aux autres formations calcaires du bassin de Paris. Cependant, dans les carrières souterraines (creutes) du Valois, du Noyonnais, du Laonnois et du Soissonnais (Picardie), plusieurs formes de paléokarst et de fantômisation (racines, tuyaux d'orgues, joints, noyaux) calées sur la fracturation de détente mécanique des vallées (extension latérale et cambrure de versant) sont observées. Des mesures de colorimétrie et de calcimétrie sur des échantillons prélevés à travers un fantôme de roche permettent de différencier nettement l'encaissant calcaire, la frange d'altération et l'altérite. Une analyse statistique des fissures et de l'organisation spatiale des carrières affectées, montre que la porosité, l'épaisseur de l'encaissant calcaire et l'homogénéité des faciès contrôlent la fantômisation. Ces observations témoignent d'une karstification polyphasée des calcaires lutétiens en bordure des vallées et en sub-surface. Deux hypothèses morphogénétiques sont alors proposées.