**6. Conclusions**

This chapter focuses on the recycling of waste natural fibers in composite materials used for construction. Fiber's recycling eliminates agriculture waste and contributes to conserving natural resources used in building materials and sustainable development.

For fibers recycling, the study of their biochemical, physical, morphological, microstructural and mechanical characteristics is essential. In addition, durability analysis of fibers helps to determine the long-term evolution of these characteristics. This chapter reviews the characteristics of natural fibers suitable for building composites such as tensile strength, water absorption, modulus of elasticity and density.

Moreover, characteristics of tropical fibers are also discussed for their reuse in earth bricks.

Analysis of natural fibers characteristics used in building materials shows the great variability in their intrinsic properties. The development of composite materials such as reinforced cementitious mortars or fiber-reinforced raw earth must consider this variability.

Natural fibers addition in building composites improves the tensile strength of these materials. Moreover, natural fibers improve the thermal and acoustic performance of composite materials.

Case studies for the recycling of natural fibers in mortar and earth bricks are also discussed. Natural fibers addition reduces the density of earth bricks and mortar. The tensile strength of earth bricks increases significantly with the addition of natural fibers. Natural fibers act as reinforcement and transform the brittle behavior of mortar and earth bricks into ductile behavior.
