eng Science and Education Publishing American Journal of Civil Engineering and Architecture 2328-3998 2025-10-19 13 5 115 122 10.12691/ajcea-13-5-1 AJCEA20251351 article Mbairangone Samson 1 Togdjim Jonas 2 Sara Gall¨¦boui 2 Kinet Ouinra 2 Civi Engineering Department, National School of Public Works (ENSTP), N¡¯Djamena, Chad Mechanical Engineering Department, Higher National Institute of Sciences and Techniques of Ab¨¦ch¨¦ (INSTA), Ab¨¦ch¨¦, Chad The study focuses on the physical, chemical, geotechnical, and mineralogical characterization of two clay soils from N'Djamena (NDJA) and Moundou (MOD) in Chad with a view to their use in eco-construction. This characterization is essential when selecting soils for use in the manufacture of raw earth bricks. After the soil samples were taken, the work was carried out experimentally in laboratories. The results of the physicochemical study reveal a moderate natural water content (12.5%) for the N'DJA soil, compared to a very high natural water content (30.6%) for the MOD soil. The NDJA soil has a relatively low organic matter content (2.27%) compared to the MOD soil (5.11%). However, both have a loss on ignition rate (6.03% and 6.57%, respectively) and specific density (2.35 g/cm3 and 2.34 g/cm3, respectively). The NDJA and MOD soils consist of 25.2% clay, 29.4% silt, and 45.4% sand, and 21.3% clay, 43.6% silt, and 35.1% sand, respectively. The results of the chemical analysis show that the abundant oxides are SiO?, Al?O?, and Fe?O?, whereas K?O, CaO, BaO, MgO, Na?O, TiO?, and P?O? are present in low quantities in the NDJA and MOD soils. The results of mineralogical analysis by X-ray diffraction (XRD) reveal that the clay in N'Djamena (NDJA) consists mainly of quartz (Q), kaolinite (ka), K-feldspar (K-f), smectite (sm), and hematite (Ha), while the clay in Moundou (MOD) also contains illite (Il) in addition to these minerals. The study showed that both soils have properties that make them suitable for use in eco-construction. https://pubs.sciepub.com/ajcea/13/5/1/ajcea-13-5-1.pdf characterization clay soils Chad density oxides eco-construction