The objective of this paper is to analyze the mechanical behavior of a clayey sand soil with added green coir fiber at 0.25%, 0.5%, 0.75%, and 1% by dry weight, through a series of laboratory tests that physically and mechanically characterize the samples in order to evaluate possible changes in the soil properties. Unconfined compression and indirect tensile tests were carried out. The addition of fibers to the soil resulted in a considerable increase in the strength of the composites. Unconfined compression strength for the soil and fiber mixtures was highest with 0.5% fiber content (50.8% higher than the soil without fibers), and the tensile strength was highest for 0.75% fiber content (85.4% increase). These results will hopefully encourage the use of vegetable fibers, specifically coir fiber, as an alternative material for use in civil engineering projects.