Four building phases
Jehay Castle in Amay in the province of Liège represents almost five centuries of history. The building was constructed in four phases. Around 1550, the sixteenth-century wing, the main building and the two round towers were built. The central wing followed between 1555 and 1585 and the imposing keep around 1640. Around 1860, architect Alphonse Balat added a gallery and a square tower to the keep. He partially reconstructed the south facade of the 16th-century wing and added a corner turret.
The castle was listed in 1974 and has belonged to the Province of Liège since 1978. Since 2013, the building has been listed as Wallonia's exceptional heritage.
Petrography of mortars and plasters
The castle has been undergoing restoration since 2017 thanks to funding from the Province of Liège and the Walloon Heritage Agency (AWaP). It is scheduled to reopen to the public in 2024. The preparatory works, which involved demolishing part of the castle, provided an ideal opportunity to gain more knowledge about the structure. For example, the Laboratory for Monuments and Monumental Decorations of the KIK carried out a petrographic study of the different mortars and plasters in the building. The experts examined a total of 85 grinding plates. Their aim? To characterise the composition of the mortars and plasters in the four construction and intervention phases. At the same time, the researchers carried out a thermal analysis. This is a technique that combines thermogravimetry and differential scanning calorimetry. This way, they not only determined the hydraulic character of the binder used in the materials, but they also came up with a reference corpus and were able to date certain parts of the castle that were previously unclear.
Study of annual rings
KIK also carried out dendrochronological studies on wooden constructions in the castle. By analysing the annual rings in wood, structures can be accurately dated. The first study was conducted in 2017 and focused on the roof structures of the various wings of the castle. The second study took place in 2018 and looked at wooden structures and elements from all the rooms on the ground floor and the first floor, such as floor beams, trusses, window slats, door frames and reused wood in the masonry. The aim was to identify some of the old circulation routes in the building, trace the reused wood and identify which construction or restoration phase they belonged to.
At the request of the Province of Liège, KIK compiled the results of both scientific studies into a single summary document. Such a comparative interpretation of two different analyses is relatively exceptional and opens the door to broader research projects in which experts also involve other disciplines and methods, such as radiocarbon dating. The result of this research was presented at the Journées d'Archéologie in Wallonia in 2019.