ED Sciences Physiques et de l'Ingénieur
Sedimentary chronicles. Fabric of an alluvial earth construction sector of the Arcachon Bay and its watersheds
by Quentin PROST (I2M - Institut de Mécanique et d'Ingénierie de Bordeaux)
The defense will take place at 14h00 - Salle 04 École Nationale Supérieure d'Architecture et de Paysage de Bordeaux (ENSAP Bordeaux) 740 cours de la Libération 33400 Talence
in front of the jury composed of
- Géraldine CASAUX-GINESTET - Professeure - ENSAP Bordeaux - Directeur de these
- Erwan HAMARD - Chargé de recherche - Université Gustave Eiffel - Rapporteur
- Nathalie TORNAY - Maîtresse de conférences - ENSA Toulouse - Rapporteur
- Denis BRUNEAU - Professeur - ENSAP Bordeaux - Examinateur
- Matthieu DUPERREX - Maître de conférences - ENSA Marseille - Examinateur
- François FLEURY - Professeur - ENSA Normandie - Examinateur
- Xavier GUILLOT - Professeur - ENSA Marseille - Examinateur
- Cyrille MARLIN - Maître de conférences - ENSAP Bordeaux - Examinateur
Can we build in raw earth with the dredged sediments of the Arcachon Bay, otherwise known in this research as "alluvial earth"? What would be the nature of a raw earth construction sector emerging from these sediments if it integrated the liveliness and complexity of the environments of the lagoon and its watersheds? These are the two essential questions posed in this thesis. In the Arcachon Bay, the accumulation of sediments in ports and channels prevents navigation over time, both for pleasure boaters and for maritime professionals. To remedy this phenomenon, dredging operations are organized. The dredged materials are deposited on land in storage basins and are then used in various "recovery sectors" (growing medium, road techniques, etc.). This dynamic places the subject of the "dredged sediment recovery sector in raw earth construction", otherwise known here as the sediment-earth sector, as an issue considered by local authorities and by the actors of an emerging raw earth sector in Gironde. To study sediments as potential earth to build and to question what the environments of the lagoon and its watersheds can do to the notion of the construction sector, an inquiry unfolds to understand sedimentary movements and to become familiar with the diversity of human and non-human relationships at play, around and with the sediments, transcribed through sedimentary chronicles. This research in an architectural experimentation situation studies some historical and contemporary resource developments of identified local environments, their factory and habitats, to imagine possible ecological assemblages and complementarities with the transformation of sediments into earth materials. In addition, the inquiry looks at some observations of forms of collaboration and hybridization of knowledge and professions in a raw earth construction sector currently being established in Gironde, France and the surrounding area, and from which to imagine correspondences with a sediment-earth sector. Also, in parallel with the physicochemical characterization of sediments, experiments are undertaken, notably through the manufacture of molded and extruded raw earth bricks. These experiments question two heritages, oyster farming and brickmaking: first, through the construction of an Experimental Pavilion with students from ENSAP Bordeaux as part of a school-construction-site re-examining oyster farming construction cultures based on a “harvesting architecture” based on sediments and oyster shells, then through the development with a local brickyard of materials whose mechanical behavior and durability are characterized. This leads to sketching the hypothesis of oyster-brickwork practices, that is to say, comparing two worlds of work with matter and the living, with the mineral and the animal, as a support for mapping the assembly of a set of human and non-human "worker" agents involved in a potential open sediment-earth sector (eelgrass, oysters, oyster farmers, rivers, sediments, bricklayers, etc.), that is to say, based on an expansion of the members of a sector attentive to the interspecific relationships that are woven around and with the sediments. To go beyond the anthropocentric approach to the sector and some of its attributes (resource, work, value) and to allow production situations to emerge in these troubled times which favour the conditions for the ecosocial reproduction of life, it is proposed to create a "milieu" to "create a sector" with research whose results suggest the possibility of building with the alluvial earth of the Arcachon Bay.