Rejuvenation of maritime signalisation structures with UHPFRC

The extremely low permeability of UHPFRC, associated to their outstanding mechanical properties makes them especially suitable to rejuvenate maritime signalization turrets or lighthouses at sea. Those structures have a very severe environment and very limited access due to tide and weather conditions. They require extremely efficient intervention methods. Similarly to what is done on existing bridge decks or building slabs, UHPFRC provide in this case a unique and robust solution with a vision to simplify and shorten the rehabilitation process with long term durability. In this context, an existing turret, off the south Brittany coast nearby Lorient (France), was reinforced with a 60 mm UHPFRC layer. The UHPFRC was cast in place by a helicopter in a formwork around the existing masonry structure. The UHPFRC mix was specifically tailored to this application with a tensile strain hardening response, limited shrinkage, and an optimized rheology (self-leveling) for a fast filling of the formwork to minimize the use of helicopter time.