Bold multi-use skyscrapers
Inclined at 5 °, which is more than the famous Pisan tower, the two “sisters” built on a narrow plot located between the outer boulevards, the ring road and along the railway tracks of the Austerlitz station, will soon house Natixis offices. / Groupe BPCE as well as other activities. Duo 1 will house 69.000 m² of offices, an auditorium, a company restaurant and shops, while Duo 2 will have 19.000 m² of offices, a company restaurant, shops, but also a hotel with 139 rooms, a restaurant and a panoramic bar. The towers are based on an infrastructure of 9 basement levels (parking, archives and technical rooms) with a total surface area of 140.000 m². Duo 1, the tallest tower, deviates from the 29th floor and various setbacks at Duo 2 level contribute to the two buildings, as a whole, forming a “V”.
Ultra-local specific concretes
Between 2017 and 2020, from its production units in Paris-Tolbiac and Ivry-sur-Seine located near the site, for Duo 2, CEMEX will have supplied Bateg, a subsidiary of VINCI Construction France with nearly 40.000 m³ of ready-to-use concrete. use: 10.000 m³ of concrete foundations for diaphragm walls, more than 29.500 m³ of civil engineering and architectural concrete for elevations, as well as high performance concretes intended for pouring a mega-beam including an integrated cooling system and supporting all the towers, the latter having been designed and delivered by the Paris Port-Victor production unit. All the concretes have been designed with formulations that lighten the building's carbon footprint, in particular for the foundations. In 2021, 150 m³ of black decorative horizontal concretes were delivered for the realization of the terraces of the two towers while the deliveries of accelerated anhydrite screed continue for nearly 2.000 m² of heated floors on the ground floor and on the upper floors. . Most of these concretes have been pumped. In addition, during these three years, thanks to its robust multimodal logistics system, CEMEX will have evacuated almost all the spoil, ie nearly 42.000 tonnes.
Technicality and communication
The specifications for the diaphragm walls of the two towers turned out to be particularly demanding: for example, it was necessary to guarantee the fluidity of the concrete for more than six hours. The demand was also very high in terms of the quality of the facings. The strong commitment of CEMEX's technical teams nevertheless led to the success of the operation. In addition, the scope of the work resulted in a very large number of contacts, and the quality of communication between the various CEMEX departments (commercial, technical, production) and the works teams also played an essential role in the fluidity of concrete deliveries. The pourings which regularly took place in very wide working hours and sometimes at weekends only reinforced the involvement of the CEMEX teams, as well as the pride of participating in such a demanding project and renowned throughout the world.