From French Earthen Heritage to Djiboutian Earthen Construction: Material Characterization and Potential for Bioclimatic Application

This study investigates the potential of raw earth as a sustainable construction material through a comparative material-scale analysis of soils from Châlons-en-Champagne (France) and Balbala (Djibouti), two contrasting geological and climatic contexts. A comprehensive multiphysical characterization was conducted, including particle-size distribution, SEM/EDX analyses, mechanical testing, thermal properties, water-vapor permeability, moisture-buffering capacity, and water-related durability. The Djibouti soil, richer in clay and more plastic, exhibits higher compressive strength and moisture-buffering capacity but greater sensitivity to erosion and rapid water saturation. The Châlons soil, richer in carbonates and more porous, shows higher specific and volumetric heat-storage capacities, whereas the Djibouti soil presents lower thermal conductivity and diffusivity. These complementary behaviors indicate distinct material-scale potentials and limitations rather than demonstrated building-scale performance. The results are therefore used to assess the potential adaptation of selected climate-responsive principles derived from French earthen heritage to the Djiboutian context, including solar protection, ventilation, moisture management, capillary breaks, and compatible protective renders. Wall- and building-scale hygrothermal performance remains to be validated using site-specific climatic data and dedicated experimental or numerical analyses.