Comparative effectiveness of fibers in enhancing engineering properties of Earth as a building Material: A review

• Suitability of fibers in improving the engineering properties of earth is reviewed. • The physical, chemical, and mechanical properties of fibers are reviewed. • The comparative effectiveness of various fibers is analyzed. • The results are compared with some existing relevant standards. • Future directions are provided based on current research gaps in this field. Earth is becoming increasingly popular as a building material to promote sustainability, considering environmental impacts and economic aspects. Recent studies have focused on enhancing the engineering properties of earth and earthen construction using different types of fibers, which is considered one of the suitable options for soil reinforcement. A comprehensive review considering the effectiveness of different fibers, their dosages, and their relationship with various engineering properties of stabilized earth is missing in the literature. Therefore, this study aims at providing a state-of-the-art review of research on the effectiveness of fiber reinforcement techniques in overcoming the limitations of the earth and enhancing the engineering characteristics of the reinforced earth. Based on 96 existing studies, the properties and types of fiber and soil, sample-making processes, and engineering properties of fiber reinforced earth, including physical, thermal, mechanical, and durability properties, are reviewed and presented in recapitulative tables. The review demonstrates that there is no specific fiber that showed the best performance considering all the properties; rather, different fibers proved to be best at improving different properties. The present study should aid in the selection of superior fibers and their suitable contents depending on the required engineering properties of earth for being used in construction. Furthermore, this study provided directions for future studies, which should focus on soil mineralogy, the effectiveness of combinations of different fibers, microstructural analysis, and the development of a widely accepted code to promote earthen construction.