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The aim of thisscientificworkis to investigate the effect of moisture content on the behaviour of borassus in concrete. At the beginning of thisstudy, characterisation tests are carried out on the materials used. These materials include Nokoue lagoonsand, rolledgravelfrom the Mono, concrete and cut-to-length rônier. Afterformulating the concrete using the DREUX - GORISSE method, the Borassus plant reinforcementsweretreated with a hydraulicwaterproofing binder (cement glue, bitumen and Flintkote Be3) and nine (09) beamswere made, three (03) per category of waterproofingtreatment. In addition, three (03) control beams are used as comparison materials. The analysis of all the results of the four-point bending tests led us to the conclusion that Flintkote Be3 and bitumen are very effective waterproofingproducts for the treatment of the surfaces of rônier wood beforethey are introducedinto the concrete, because the smaller the variation in the moisture content of the beams (example of PARB beam: 2.36%), the greater the resistancetheydevelop to the appliedload (example of PARB beam: 19.36 ± 1.84 kN) and consequently the lower the deformability of the beams. It thenappearsthatbitumen and Flintkote Be3 canthereforeact as a productthateliminates the dimensional variations of borassus reinforcements in concrete and provides good resistance of borassus-reinforced structures.

The aim of the presentworkis to study the viscoelastic model of Borassus Aethiopum Mart whichis relevant for the characterisation of a Borassus Pre-stressedConcretebeam. Mechanical tests werecarried out mainly the creep test on typical Borassus Aethiopum Mart specimensfrom the Pahou-Ahozon forestgallery in southern Benin, Africa, subjected to a constant bending stress along the beam. The moisture content of the specimensis set at 12% and isobtained by kilndrying at ATC du Bois. The loadinglevel of the specimensis set at 20% of the failureload. A methodologystartingfrom the determination of the compressive and bending stresses of Borassus Aethiopum Mart for the identification of the optimal values of the dynamicelasticmodulus E and the dynamicviscosity constant η of Borassus Aethiopum Mart with the non-linear least squares methodapplied to the Kelvin Voigt rheological model. The instantaneousmodulus of elasticity E0 wasdeterminedfromHookeslaw. A series of validation tests wereperformed on the numerical model. Finally, a comparison of the numerical model with the rheologicalrepresentationconfirmed the previousresults.