Effect of fiber reinforcement on the isotropic compression behavior of a sand

High-pressure isotropic compression tests were carried out on samples of a uniform fine sand at different initial specific volumes, reinforced with randomly distributed polypropylene fibers (0.5% by weight, 24 mm in length and 0.023 mm thick), as well as on a nonreinforced sand specimen. Analysis of the results identified changes in the isotropic compression behavior due to the random inclusion of fibers into the sand. Two distinct and parallel normal compression lines were observed for the fiber-reinforced and nonreinforced sand. The fibers were exhumed after testing and it was found that fibers had both extended and broken, indicating that the fibers tend to suffer large plastic tensile deformations before breaking and that the fibers act under tension even in isotropic compression.