eng Science and Education Publishing American Journal of Civil Engineering and Architecture 2328-3998 2026-07-15 14 4 137 145 10.12691/ajcea-14-4-1 AJCEA20261441 article ZETOME Herv¨¦ hervzet85@gmail.com 1 TANKPINOU KIKI Yvette 1 BONOU Sourou A. Sidoine 2 GBAGUIDI S. Victor 3 Laboratoire des Proc¨¦d¨¦s et de l¡¯Innovation Technologique, Universit¨¦ Nationale des Sciences, Technologies, Ing¨¦nierie et Math¨¦matiques (UNSTIM/Abomey/Benin) X-ray Techniques Laboratory (X-TechLab/S¨¨m¨¨ City/Benin) Laboratoire d¡¯¨¦nerg¨¦tique et de M¨¦canique Appliqu¨¦es (LEMA/Abomey-Calavi/Benin) The issue of sustainable development combined with environmental protection deserves careful consideration in all sectors of human activity, particularly infrastructure, buildings, and transportation. Indeed, in the drive to preserve the environment, the introduction of natural fiber materials as substitutes for conventional materials in various areas of construction is essential due to their renewable and biodegradable nature. Several national and international studies have been conducted on the physical, mechanical, chemical, and biochemical characteristics of composite materials for possible use in construction. However, these studies have not been fully exploited due to a lack of research on the long-term behavior of these composite materials. The objective of this study is therefore to determine the optimal fiber content that will maximize the mechanical performance of the clay sand-fiber composite. Two geosourced materials, ¡°Zinvié clay sand rated S1¡± and ¡°Abomey-Calavi clay sand rated S2,¡± and one bio-sourced material, ¡°coconut fibers rated FNC,¡± were used. The methodology adopted consists of adding the fibers to the matrix in the form of random inclusions. The different fiber contents considered were as follows: 0.6%, 0.8%, 1%, 1.2%, and 1.4%. After formulation, 4×4×16 cm³ test specimens and cylindrical test specimens were prepared and stored at a temperature of 20°C until maturity to prevent cracks due to shrinkage. The test specimens were subjected to physical and mechanical tests, and the results obtained show that coconut fibers reduce the clay content and permeability of the materials and increase their flexural strength, compressive strength, bearing capacity, and shear strength. https://pubs.sciepub.com/ajcea/14/4/1/ajcea-14-4-1.pdf Coconut fibers clayey sand permeability bearing capacity compressive strength flexural strength