The footbridge is based on 142 reinforced concrete beams of gigantic proportions: 1,20m of diameter and a depth of about thirty meters! To manufacture the 5 000m3 of the concrete required to their construction, the CEM III/A 52,5 L PM-ES LafargeHolcim cement, manufactured at Le Havre plant, was used.
This slow setting cement is indeed particularly well adapted to the aggressive environment of the Mont Saint-Michel bay (sea water, salt, tides) and allows the manufacturing of a high resistance concrete after 28 days. All these assets perfectly meet the requirements of this exceptional project!
Furthermore, thanks to its low clinker content, this cement contains a reduced CO2 rate: it has also allowed reducing the environmental impact of concrete by 47 % compared to those using traditional cements (CEM I). An important point on a site where the environmental aspect (such as noise pollution, quality of water...) is closely monitored!
With the solid foundations of its footbridge, the Mont Saint-Michel will become an island again during the big tides and it will recover its natural aspect for the greater delight of the 2 to 3 Million visitors every year!