The 'Maagdentoren' of Zichem (Belgium) : damage assessment of ferruginous sandstone by X-ray tomography

The ferruginous sandstone of the gothic “Maagdentoren” is suffering from a specific biological deterioration process triggered by perforating activities of mason bees. The damage due to these perforations causes extensive loss of material, so that a durable conservation of such degraded stone blocs becomes questionable. In order to evaluate the conservation possibilities of stone blocs damaged by perforating mason bees, an investigation of the internal structure by means of X-ray tomography was carried out. This investigation revealed that the cumulative effect of the digging work by multiple generations of mason bees may result in networks of perforations. Bioturbated sandstones were found to be most suitable for attack by mason bees because of morphological and geometrical compatibility between the original layered burrowings by marine organisms and those by the mason bees. As a conclusion the conservation is not recommended of sandstone blocs for which the load bearing capacity is endangered by the branched and layered perforations

The confinement of mortar in masonry under compression: experimental data and micro-mechanical analysis

The present paper deals with the behavior of several types of mortar in masonry under compression. The quantification of the response of mortar to triaxial confinement afforded by the masonry units in the composite subjected to compressive stresses is paramount in the determination of the peak stress of wallettes and pillars under compression. This behavior is greatly affected by the behavior of the mortar micro-structure and is manifested by the constrained lateral expansion of the mortar in the joint. A series of experimental results is presented, carried out on different assemblages of masonry composites (couplets and wallettes) with different types of masonry units and mortar, ranging in type from pure lime to cement based mortars. These experiments are subsequently simulated numerically using micro-mechanical techniques accounting for the shifting behavior of the Poisson's ratio of the mortar for varying levels of applied compression. Masonry is treated in a micro-mechanical framework as a composite material composed of two macroscopically distinct material phases: units and mortar. The experiments and their simulation provide insight into the complexities of masonry under compression that need to be accounted for in numerical analysis, including a discussion on the progression of damage in each material phase. The results and their analysis are further enriched through a comparative parametric study. A clear difference emerges between the assigned and the apparent Poisson's ratio for the material components.Funding for this work was procured through the GEPATAR project (“GEotechnical and Patrimonial Archives Toolbox for ARchitectural conservation in Belgium” BR/132/A6/GEPATAR), which is financially supported by BRAIN-be, BELSPO (Belgian Research Action through Interdisciplinary Networks, Federal Public Planning Service Science Policy Belgium).Peer ReviewedPostprint (author's final draft

Damage assessment of ferruginous sandstone by X-ray tomography : the 'Virgin Tower' of Zichem (Belgium)

The ferruginous sandstone of the Gothic “Virgin Tower” is suffering from a specific biological deterioration process triggered by perforating activities of mason bees. The damage due to these perforations causes extensive loss of material, so that a durable conservation of such degraded stone blocks becomes questionable. In order to evaluate the conservation possibilities of stone blocks damaged by perforating mason bees, an investigation of the internal structure by means of X-ray tomography was carried out. This investigation revealed that the cumulative effect of the digging work by multiple generations of mason bees may result in networks of perforations. Bioturbated sandstones were found to be most suitable for attack by mason bees because of morphological and geometrical compatibility between the original layered burrowings by marine organisms and those by the mason bees. As a conclusion, the conservation is not recommended of sandstone blocks for which the load bearing capacity is endangered by the branched and layered perforations

14C dating of the lime burial of Cova de Na Dent (Mallorca, Spain): optimization of the sample preparation and limitations of the method

Lime burials are a characteristic phenomenon of the protohistoric funerary tradition on the Balearic Islands. At Cova de Na Dent, six samples, representing the entire stratigraphy of the lime burial, were taken for analysis. The radiocarbon dates suggested that the lowest levels of the burial were Late Bronze Age. This is in contradiction with the general belief that the lime burials are a late Iron Age phenomenon. Therefore, a new analysis strategy is put forward, focusing on the so-called 1st fraction, the first CO2 released during the acid lime reaction, which is supposed to be free of fossil carbon. The analysis demonstrates the impossibility to eliminate the fossil carbon fraction completely. This is probably due to the different geological formation of the local limestone deposits (ancient reef barriers) compared to the previous lime burials of Mallorca all coming from mountain areas. C-14 analysis from a cremation layer without lime at the onset of the lime burial reveals an Iron Age origin of the Cova de Na Dent lime burial

Provenance study of the limestone used in the cremation rite: the case of Cova de sa Prior (Binigaus, Menorca)

[eng]Because hardly any charcoal is found in the lime burial of Cova de sa Prior as well as in many other lime burials on the Balearic islands, the question was raised if the cremation ritual was performed on site or not . Samples of the lime conglomerate and lime lumps were compared with limestone from the cave itself as well as from the area around the cave. Thin-section petrography of the lime conglomerate and lumps gave no relevant information about the provenance of the limestone used for the cremation rite, but preserved structures of the source rock found in an incompletely burned limestone fragment showed that most probably the limestone comes from the direct vicinity of the cave or even from within the cave itself.[cat]L’absència gairebé absoluta de carbons a l’enterrament en calç de la cova de sa Prior, així com a molts altres enterraments d’aquest tipus a les illes Balears, va fer plantejar si el ritual de cremació hauria tingut lloc a l’interior de la cova o no. Es varen comparar mostres del conglomerat i dels pilots de calç amb la roca calcària de la mateixa cova i dels seus voltants. La petrografia de la làmina prima del conglomerat i els pilots de calç no va proporcionar informació rellevant sobre la procedència de la calcària utilitzada al ritual de cremació, però les restes inalterades conservades a un fragment de roca calcària cremat de manera incompleta evidenciaren que, molt probablement, la matèria primera prové de l’entorn directe de la cova o, fins i tot, del seu interior

Soil settlement and uplift damage to architectural heritage structures in Belgium: country-scale results from an InSAR-based analysis

Soil movement may be induced by a wide variety of natural and anthropogenic causes, which are detectable in the local scale, but may influence the movement of the soil over vast geographical expanses. Space borne interferometric synthetic aperture radar (InSAR) measurements of ground movement provide a method for the remote sensing of soil settlement and uplift over wide geographic areas. Based on this settlement and uplift evaluation, the assessment of the potential damage to architectural heritage structures is possible. In this paper an interdisciplinary monitoring and analysis method is presented that processes satellite, cadastral, patrimonial and building geometry data, used for the calculation of settlement and uplift damage to architectural heritage structures in Belgium. It uses processed InSAR data for the determination of the soil movement profile around each case study, of which the typology is determined from patrimonial information databases and the geometry is calculated from digital elevation models. The impact on the historic structures is calculated from the determined soil movement profile based on various soil-structure interaction models for buildings. The Declercqresulting damage is presented in terms of a numerical index illustrating its severity according to different criteria. In this way the potential soil movement damage is quantified in a large number of buildings in an easily interpretable and user-friendly fashion. The processing of InSAR data collected over the previous 3 decades allows the determination of the progress of settlement- and uplift-induced damage in this time period. With the integration of newly acquired and more accurate data, the methodology will continue to produce results in the coming years, both for the evaluation of soil settlement and uplift in Belgium as for introducing related damage risk data for existing architectural heritage buildings. Results of the analysis chain are presented in terms of potential current damage for selected areas and buildings.The authors wish to acknowledge the funding received by BRAIN.be, BelSPO in support of the GEPATAR research project (“GEotechnical and Patrimonial Archives Toolbox for ARchitectural conservation in Belgium” BR/132/A6/Gepatar)Peer ReviewedPostprint (published version

Advanced processing of remotely sensed big data for cultural heritage conservation

Damage assessment, protection and preservation of built patrimony are a priority at national and local levels due to their importance to many cultural and economic aspects. This paper presents a methodology to estimate the potential damage caused by ground settlement for cultural heritage buildings using remotely sensed big data. Specifically, it presents a framework to assess the potential damage caused by ground settlement for masonry, infilled and bare frames structures using Persistent Scatterer Interferometric (PSI) measurements. The proposed solution advances the state-of-the-art by integrating big Earth observation (EO), environmental, architectural and historical data, for estimating the settlement induced damage to hundreds thousands of buildings. The fully automatic scheme was created within cloud computing environment for accelerating data transfer, processing and modeling and for improving the visualization of image-derived products.Peer ReviewedPostprint (author's final draft