Impact of Environmental Exposure on Historical Building Materials in the Archaeological Cellar of Our Lady’s Basilica in Tongeren (B)

Abstract 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.