The present investigation determines the influence of abaca (Musa textilis) fiber inclusion on the simple compressive strength of reconstituted sandy silt specimens. For this purpose, fibers of different lengths (5, 10 and 15 mm) and quantities (0.5, 1.0, 1.5 and 2.0% of soil dry weight) are added to produce the reconstituted specimens. Subsequently, the physical and mechanical behavior of soil–fiber mixtures were evaluated through compaction and unconfined compression tests. The experimental results showed that increases in fiber content or length, or both, led to a 1235.1% increase in maximum compression stress (compared to the fiber-free soil). Compression failure occurred at a greater axial strain when 10 and 15 mm fibers were added at 1% dosage or in percentages equal to or greater than 1.5% regardless of fiber length. A series of linear mixed models identified statistically significant effects of fiber length and percentage on the level of effort and on the unitary deformation.