In Africa, the cotton industry is one of the most important agricultural sectors. In Benin, a record 730,000 tonnes will be produced in 2020-2021, making the country the leading producer of the white gold in Africa. Although essential to the economy, fourteen types of residue from cotton processing remain unexploited. This waste is generally burnt by producers, which contributes to environmental pollution through the emission of greenhouse gases. To overcome this problem, we focused our work on recycling cotton fiber waste into a cotton fiber-starch composite material for use as false ceiling panels in the building industry, in place of the plywood generally used. To achieve this, we manufactured sheets from our composite material to determine mechanical properties such as modulus of elasticity and flexural modulus of rupture in accordance with NF EN 310. Three-point bending loading-unloading cycles were performed. The plates manufactured have dimensions of 300x300x100mm3. The plates are manufactured with «starch/water» and «starch/cotton fiber» mass ratios respectfully equal to 0.25 and 1. We obtained a modulus of elasticity equal to 2830 MPa and a modulus of rupture equal to 11.53 MPa.

The present work is taken into account for the study of the possibility of substituting steel reinforcements by reinforcements of Borassus Aethiopum Mart. Specifically, the purpose of our study was the use of Borassus in the field of prestressing. Several tests have been carried out for this purpose. The characterization tests of the materials carried out at the beginning of this study on the constituents of the concrete made it possible to adopt a concrete formulation by the DREUX-GORISSE method. This allowed us to make six test pieces; Three with steel reinforcements and three others in frame of Borassus. After their preservation for 28 days, they were subjected to flexion tests four points. Thus the loads and the arrows induced were recorded for the different types of concretes. In addition, we performed the direct traction test. This test allowed us to define the elastic zone of our framework of Borassus. A simulation of the flexion test four points on the Borassus reinforced concrete subjected to prestressing by pre-tensioning was then made. This taking into account the elastic zone of our framework and the physical and mechanical characteristics of the reinforced concrete of Borassus. The overall flexural behavior of four points of prestressed beams by numerical simulation and those of reinforced concrete of steel reinforcements were analyzed. The results obtained allow us to conclude that the elastic stress of Borassus reinforced concrete subjected to prestressing is superior to that of reinforced steel.