Análise do comportamento mêcanico de um solo estabilizado com cimento e reforçado com fibra de coco para fins de pavimentação

Abstract

Soils available in local borrow pits do not always present geotechnical characteristics compatible with the structural requirements of pavement layers, making it necessary to adopt stabilization and reinforcement techniques. Cement stabilization is widely used in this context; however, it may result in materials with brittle behavior and high susceptibility to cracking. As an alternative, the incorporation of natural fibers plays the role of structural reinforcement in these mixtures, while also promoting the reuse of residues. In this context, this study evaluated the mechanical behavior of soil mixtures stabilized with cement contents of 5%, 7%, and 9%, combined with the incorporation of coconut fiber at contents of 0.25%, 0.75%, and 1%, with a fixed length of 25 mm. For comparative purposes, natural soil, soil–cement, and soil–fiber mixtures were also analyzed. The experimental program comprised geotechnical characterization of the soil, compaction tests, and mechanical evaluation through Unconfined Compressive Strength (UCS), Indirect Tensile Strength (ITS), California Bearing Ratio (CBR), and Resilient Modulus (RM) tests. Based on the experimental data, mechanistic–empirical pavement design was performed using the MeDiNa software. The results showed that soil– cement mixtures without reinforcement did not reach the minimum UCS value of 2.1 MPa required by standards for application as base layers, whereas the incorporation of coconut fiber promoted strength gains sufficient to meet this requirement, in addition to modifying the failure mode, resulting in a more ductile structural behavior. Among the compositions evaluated, the mixture containing 5% cement and 1% fiber presented the best balance between mechanical performance and material consumption. The mechanistic–empirical design results indicated that soil–cement–fiber mixtures meet the performance criteria for different traffic levels, including higher traffic scenarios, provided that structural layer thicknesses compatible with design requirements are adopted. The potential of this composite material for application in pavement base layers was evidenced, while soil–fiber mixtures proved suitable for subbase layers, highlighting the technical feasibility of the solutions, reduced binder consumption, and environmentally appropriate destination of the residue