Retrofitting of Historic Watchtower in Abu Dhabi, UAE

The historic fort of Qasr Al Hosn is a landmark at the heart of the modern city of Abu Dhabi, UAE. It includes the city’s oldest permanent structure, a coral and sea stone watchtower built to protect the settlement of Abu Dhabi first established on the island in the 1760s. The tower forms the only surviving part of a square fort, constructed around 1800 CE as the stronghold and seat of government of the ruling Āl Nahayyān family. Qasr Al Hosn was enlarged by Shaikh Shakhbūt Bin Sultān Āl Nahayyān in the 1940s and extensively restored in the 1980s. In light of its historic importance, Qasr Al Hosn underwent an extensive conservation and retrofitting campaign, starting in 2013, which concluded with the reopening to the public in December 2018. This paper deals with the development of the conservation strategy for the Old Watchtower: the intervention aimed both to remedy damage and to improve the structural performance of the tower without further affecting the original materials. The inner r.c. lining that had been built in the 1980s and that was deemed the main culprit for the damage to the historic stonework was removed in stages; careful repair and strengthening of the masonry fabric was carried out, using traditional materials and techniques. Additionally, basalt fibres were bonded in the outer plaster layers so as to enhance the seismic response of the structure and comply with current code prescriptions regarding structural safety. The paper details the survey, design process and implementation of the strengthening measures as well as a recent maintenance intervention, which targeted the detachment of the plaster and fibre strips. This latest intervention prompts a number of considerations on improvements and changes that should be considered in future interventions.