Effect of the reuse of plastic and metallic fibers on the characteristics of a gravelly soil with clays stabilized with natural hydraulic lime

A series of tests were carried out to study the combined effect of plastic fiber, metal fiber, and the optimum percentage of natural hydraulic lime (NHL) in gravelly soils with clays. The methodology employed was to incorporate lime percentages of 2, 4, 6, 8, and 12% by weight into the natural soil, determining the optimum lime content by UCS test. Then, combinations of 0.5PF5MF8NHL, 1PF10MF8NHL, 2.5PF15MF8NHL, and 3.5PF20MF8NHL, respectively, were made to replace the natural soil. The PFs had a dimension of 40 mm long and 5 mm wide, and the MFs had a dimension of 100 mm long and 5 mm wide. The latter underwent chemical treatment before being included in the soil itself. Various tests such as Atterberg limits, compaction, California bearing capacity (CBR), and unconfined compressive strength (UCS) were performed to understand the impact of the additives on the soil. As novel results, the soil does not present plasticity when fibers are combined with NHL. In addition, both the optimum moisture content and maximum dry density show inversely proportional values of significant reduction and increase as a function of the combinations. On the other hand, the 1.5PF10MF8NHL combination showed an improvement in strength gain in the CBR of 152.11% and the UCS test of 759.80% at 28 days. However, the remaining combinations showed improvement, but not as significant as 1.5PF10MF8NHL. It is concluded that the combination of the three additives together has a significant positive impact on the mechanical properties of gravelly soil with clays, achieving successful stabilization.