Physical, thermal and mechanical properties of adobes stabilized with fonio (Digitaria exilis) straw

Abstract : This study deals with the influence of fonio straw on the physical, thermal and mechanical properties of adobes. The raw materials (soil and fonio straw from Burkina Faso) were characterized from the chemical (ICP-AES), mineralogical (XRD, DSC-TGA, IR), geotechnical (particle size distribution, Atterberg limits, methylene blue value) and microstructural (SEM-EDS) points of view. The physical (thermal conductivity, capillarity water absorption, porosity, erodibility) and mechanical (compressive and flexural strength) properties of the adobes were studied with specific attention paid to their damage and fracture behavior. Because of the biochemical composition of fonio straw (presence of quasi-crystalline cellulose and hemicelluloses, which are hydrophilic compounds), its association with the clay matrix increased water absorption and was accompanied by a significant porosity due to the air trapped during mixing. The insulating character of the cellulose and the low density resulting from the high porosity contributed to an appreciable reduction of the thermal conductivity of these adobes. The use of small amounts of fonio straw improved the mechanical properties of the adobes and made them less brittle. This improvement was linked to the good adhesion between fonio straw and the clay matrix, greatly reduced propagation of fissures in the composites and the high tensile strength of fonio straw because of its cellulose content. Thus, fonio-straw-reinforced adobes have interesting properties for use as cheap construction materials in the Sahelian zones and could contribute significantly to the thermal comfort of the inhabitants in this hot climate.
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https://hal.insa-toulouse.fr/hal-02082219
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Submitted on : Thursday, March 28, 2019 - 10:20:50 AM
Last modification on : Friday, October 25, 2019 - 6:16:35 PM

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Moussa Ouedraogo, Kalifala Dao, Younoussa Millogo, Jean-Emmanuel Aubert, Adamah Messan, et al.. Physical, thermal and mechanical properties of adobes stabilized with fonio (Digitaria exilis) straw. Journal of Building Engineering, Elsevier, 2019, 23, pp.250-258. ⟨10.1016/j.jobe.2019.02.005⟩. ⟨hal-02082219⟩

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