Volume 22, Issue 4-6 -

Reed ( Phragmites australis (Cav.) Trin. ex Steud.) is a traditional building material in many parts of the world and provides service lives of more than 50 years when used for thatching. However, during the last decades a significant number of thatched roofs showed premature failure due to decay. Potential reasons for this are manifold but not clearly identified, yet. This monitoring project aimed therefore on investigating the moisture and temperature conditions within a thatched roof structure showing severe degradation after only seven years in service to obtain more information about the decay risk of reed and its potential causes. Highest moisture loads were found on the outermost layers of the North-faced roof, which also showed superficial growth of algae, lichens, and mosses. However, it stayed unclear if increased moisture content ( MC) was the reason for or the consequence of decay. An increased MC was also found where the roof pitch turned from steep to flat. The use of so-called substitute sensors made from preservative treated wood turned out as a useful method to determine equilibrium moisture contents as well as time of wetness in reed structures and might be applied also for further field testing and monitoring with reed, straw, or other organic fibrous materials.

Calcareous materials such as limestone and lime-based mortars, widely used in the Built Heritage, are often subjected to degradation processes that can lead to loss of cohesion and material loss. Consolidation of these materials with liquid products via the surface is a common practice; however, the most used consolidation products (e. g. TEOS-based) show a poor physical-chemical compatibility with calcareous substrates. For application on calcareous materials, the so-called nanolimes, i. e. dispersions of lime nanoparticles in alcohols, are an alternative to TEOS-based products, thanks to their chemical compatibility with lime-based substrates. Nanolimes can help to recover a superficial loss of cohesion. However, their in-depth consolidation effect is not always satisfactory. Previous work has shown that a better deposition of lime nanoparticles in depth can be achieved by adapting the properties of the nanolime dispersion (kinetic stability and evaporation rate) to the moisture transport properties of the substrate, through optimization of the solvent. In this paper, freshly synthetized nanolimes were dispersed in pure ethanol and/or in binary mixture of ethanol (95 %) and water (5 %). These nanolimes were applied on Maastricht limestone and on a lime-based mortar by capillary absorption (method commonly used for laboratory tests) and by nebulization (method widely used in situ ). The aim of this research is to fill the gap between laboratory tests and on site application, providing an application protocol for restorers and professionals in the field. The research shows that results obtained by application by capillary absorption do not always correspond to those obtained by nebulization. This fact should be considered when deciding on the use of a consolidation surface treatment in practice.

This paper is aimed at achieving a better understanding of the original state before the restoration project in 1931 and the current structural state of the great Mosque of Mohamed Ali in citadel Cairo, Egypt. A 3-D finite element model for the whole Mosque was constructed for these purposes. Elastic analysis under static and lateral earthquake loads was conducted to verify the efficiency of the main covering domes restoration project in 1931 and to specify the positions of the critical stresses. The accurate and detailed information that was collected during the restoration project in 1931 concerning the structure of the Mosque was used as database for identifying the geometrical and structural properties of the model. The results provide insight to the structural behavior of the Mosque and the current state of stresses. The study also verifies the main causes for the valuable restoration project in 1931, where the stone domes and semi-domes covering the Mosque were replaced by reinforced concrete one . Also, the places of the Mosque that need more sophisticated analysis could be identified.

An archaeological cellar has been excavated under the Basilica of Our Lady in Tongeren, as part of an extensive restoration and revitalization campaign that started in 1999, Figure 1. The cellar will enable to descend to the early Roman history of the site under and surrounding the basilica. The excavation and construction of the archaeological cellar were finished in 2007. After that the air-conditioning system and the accessibility of the cellar were installed In successive phases. At present, the integration of the archaeological cellar under the basilica with the archaeological field around the basilica is under construction. Building in the large cellar under the complete church without endangering the stability of the building was a complex construction work, as explained further in the paper. The project was realized in successive phases, to enable continuous use of the church for services as well as its accessibility as pilgrimage site. After the construction of the cellar, the focus shifted to the conservation of the archaeological remains in view of the future (touristic) exploitation of the cellar. In view of that, climate control in the cellar is crucial. The foundation footings and walls have been covered underground during centuries, and are now suddenly exposed to an inside environment with higher temperatures and lower humidity. The climate control measures during the construction works are presented, as well as the performance of the final permanent climate control installation. The specific consolidation and conservation works on the foundation masonries are profoundly discussed.