BUILDING THE CITY WITH EARTH : pisé (Rammed earth), an essential material for the urban expansion of Lyon (15th-19th centuries) ; CONSTRUIRE LA VILLE EN TERRE : le pisé, matériau essentiel de l'extension urbaine de Lyon (XVe-XIXe siècles)

This architecture thesis advances the historical knowledge on the use of rammed earth (Pisé) in Lyon and offers an unprecedented reading. It highlights the importance of this material in the urban history of the city, from the Middle Ages to the early 1900s.While rammed earth was thought to have disappeared from the Lyon urban landscape, this research yields an unprecedented corpus of 750 buildings possessing rammed earth elements located on the Lyon Metropolis territory, with 365 within the city of Lyon, including in UNESCO area. The tools used for the analysis of these buildings are numerous and complementary: quantitative and qualitative analysis, data synthesis and spatial reading using GIS, cartographic reconstruction, morphological analysis, redrawing and photography.The assembled corpus includes buildings located in the old suburbs as well as in the vast districts urbanized in the 19th century. The cross-observations, enabled by the diversity of the analysis tools used, allow to firmly conclude that rammed earth played an essential role during the successive urban expansions of the city in spite of the various regulations implemented for its use.Contrary to preconceived ideas, the elements of this corpus are not limited to rural buildings which would today be included in the city or modest urban buildings which would have been partly self-constructed. The corpus also presents many major properties (castles, bourgeois houses, hospitals, etc.) as well as very high apartment buildings (up to six levels) which make Lyon one of the cities where rammed earth buildings are the tallest in the world.Finally, this corpus illustrates a remarkable mastership of this construction technique and reflects the fundamental role of this economic material in the urbanization of Lyon.This thesis therefore proposes a new perspective on the constructive and urban history of the city and its heritage implications. More broadly, in the current context of ecological crisis, it carries a prospective dimension on the potential of ...