Soil is still the main material used to build homes in the Bouenza department. The geotechnical characteristics of Nkayi's soil have shown that it is fine and clayey. It is ideal for the production of mud bricks, with an optimal water content of around 15%. Infrared and XRD analyses showed that the soil consists mainly of kaolinite and geothite. SEM analysis showed a microstructure of separate aggregates and an open texture. Physical nitrogen adsorption showed that it has a BET specific surface area of 32.8433 m2/g and the presence of three-dimensional mesopore porosity centered at 5.2 nm, 7 nm and 12.5 nm. Similarly, this soil has promotional potential in the earth construction sector.