Strength and Deformation Characteristics of Dune Sand Earth Blocks Reinforced with Natural and Polymeric Fibers

In this paper, we present a strength and deformation evaluation of earth blocks reinforced with different types of fiber. A natural palm tree fiber and two other types of synthetic polyolefin fibers were used to improve earth blocks’ strength and stiffness. The soil used to cast the earth blocks was composed of dune sand, which is extensively available in the United Arab Emirates and most Gulf Cooperation Council (GCC) deserts, and clayey silt soil acquired from Al-Ain city, UAE. Sixteen different mixes were prepared for this study. Two identical earth blocks were cast in a wooden mold from each mix to form a total of 32 blocks. After compaction, the blocks were consolidated under pre-specified pressure, air dried, and tested to failure in the compression machine. The main parameters investigated in this study were clay content, fiber types and percentages, and cement content. The results indicate that the addition of natural or polymeric fiber to cast earth blocks significantly improved their compressive strength. The maximum compressive strength of improved blocks showed an increase of more than 30% above the maximum compressive strength recorded for identical soil blocks without fiber. In addition, the post-peak and pre-peak strength behaviors of the earth blocks are different with different fiber contents. Finally, the addition of 0.5% cement to the fiber-reinforced blocks showed a negligible effect on the peak compressive strength. However, cement content improved the early stage (small strain) stiffness of earth blocks.