Thermo-Physical Potential of Recycled Banana Fibers for Improving the Thermal and Mechanical Properties of Biosourced Gypsum-Based Materials

Abstract

The development of bio-sourced materials is essential to ensuring sustainable construction; it is considered a locomotive of the green economy. Furthermore, it is an abundant material in our country, to which very little attention is being given. This work aims to valorize the waste of the trunks of banana trees to be used in construction. Firstly, the physicochemical properties of the fiber, such as the percentage of crystallization and its morphology, have been determined by X-ray diffraction tests and scanning electron microscopy to confirm the potential and the impact of the mode of drying on the quality of the banana fibers, with the purpose to promote the use of this material in construction. Secondly, the results obtained with the gypsum matrix allowed us to note a preponderant improvement in the composite's thermal properties thanks to the variation of the banana fiber additive. Thirdly, the impact of the nature of the banana fiber distribution (either fiber mixed in matrix or fiber series model) on the flexural and compressive strengths of the composites was studied. The results obtained indicate that the insulation gain reaches up to 40%. It depends on the volume fraction and type of distribution of the banana fibers. However, the thermal inertia of the composites developed, represented by thermal diffusivity and thermal effusivity, was studied. Results indicate a gain of 40% and 25%, respectively, in terms of thermal diffusivity and thermal effusivity of the developed composites compared to plaster alone. Concerning the mechanical properties, the flexural strength depends on the percentage of the volume fraction of banana fibers used, and it can reach 20% more than the flexural strength of plaster; nevertheless, there is a significant loss in terms of the compressive strength of the studied composites. The results obtained are confirmed by the microstructure of the fiber banana. In fact, the morphology of the banana fibers was improved by the drying process. It reduces the amorphous area and improves the cellulosic crystalline surfaces, which assures good adhesion between the fiber and the matrix plaster. Finally, the dimensionless coefficient analysis was done to judge the optimal proportion of the banana fiber additive and to recommend its use even on false ceilings or walls.