“One day or another”, it would have fallen “under its own weight”… The experts explained Tuesday before the criminal court the construction defects which caused the collapse of a balcony in Angers in 2016, taking 18 students and killing four. denouncing “a form of DIY”, consulting engineer Pierre Lemaire, an expert approved by the Court of Cassation, describes the general environment of the construction site carried out in 1997-1998 on the Le Surcouf residence as “mediocre”. Here are the main elements identified as having led to the disaster.
1. “Wet” concrete
Concrete, to porosity “very high“, has been “wet” say the experts, that is to say that “there were additions of water at the time of molding to facilitate its implementation”. “All companies know very well that we do not have the right to do so”, underlined Pierre Lemaire. Bad quality, “not vibrated properly”this concrete also contained “many air bubbles”.
2. Incorrectly positioned steels
The steels, which have “a preponderant role in the stability of the slab”, were also “very badly positioned” car “far too low”also pointed out the consulting engineers.
3. Poor concreting between the building and the balcony
This resumption of concreting between the building and the balcony was poorly carried out. However, it “plays an essential role in this kind of accident”, noted Mr. Caussé-Giovancarli, who had encountered a similar situation after the fall from the balcony of the deputy-mayor of Issy-les-Moulineaux André Santini (UDF ), in January 2007. The balcony had at the time involved six others in its fall, without causing any casualties. In the case of Angers, the surface was “smooth at the level of gluing”, when it should have been beveled with rough edges to allow better grip. Over the years, a crack opened up, allowing water to seep in and the steels to oxidize. “The steels were more than rusty, they were degraded in their mass”, underlined Pierre Lemaire. Due to this «corrosion progressive», “the balcony would have fallen on its own, a few years later”he added.
4. Work carried out without respecting the plans of the concrete engineer
While the plans had been designed for prefabricated balconies, they were ultimately cast in place. If these plans had been followed, the balcony could have supported 35 people, almost twice the number of victims on the evening of the tragedy. Emphasizing that the original plans had been abandoned “almost at the start of construction”, Mr. Caussé-Giovancarli specified: “For months, the steels were in full view of everyone, it should have caught the eye” on this change of mode of construction. He points in particular to the responsibility of the architectural firm, which was to “aim in particular for the execution plans of the company”.
The trial is due to end on March 4.