Résumé
French Guiana needs affordable local building materials to cope with high population growth and the high cost of imported cement. Earthen construction could represent a local, cost-effective, and ecologically friendly alternative. However, earth materials are highly vulnerable to water, which represents a significant concern in humid tropical climates. Although hydraulic binders effectively stabilize earthen construction, they increase economic and environmental costs. Biopolymers could offer a sustainable alternative, but their effectiveness varies depending on the nature of the soil. French Guiana has highly weathered soils with a high iron and aluminum oxide content, and it remains unknown if biopolymers could be used to stabilize this type of soils. This study had three objectives. First, assess some soil diversity by examining the chemical and min-eralogical composition of 17 soils. Second, identify locally available biopolymers that can be extracted from waste or agricultural by-products. Finally, examine the interactions between two different soils and tannin, a well characterized biopol-ymer used ancestrally to stabilize the lateritic construction. Results revealed that the soils were predominantly composed of SiO2, Al2O3 and Fe2O3 in different proportions and infrared spectroscopy allowed the identification of three different minerals: kaolinite (clay), gibbsite (aluminum oxide) and goethite (iron oxide). Five local by-products were identified for the extraction of biopolymers for earth stabilization: tannin, starch, mucilage, cow dung and chi-tosan. Additionally, a complex reaction between tannin and iron oxide was observed in the iron-rich soil, highlighting the importance of selecting a soil adapted to the biopolymer. Altogether, this study gives a first insight into the potential of bio-stabilized earth construction in French Guiana, highlighting the need for further research to determine how the five locally identified biopolymers improve the water-resistance of earthen construction.