Sustainable stabilization of low-plasticity clay soils using sawdust treated with citric acid: experimental and microstructural study

Quispe Campos A.D.; Garcia Chumacero J.M. · Innovative Infrastructure Solutions (2026) · DOI: 10.1007/s41062-026-02831-7

Resumen

Low-plasticity clay soils constitute a recurrent geotechnical challenge for unpaved road infrastructure in rapidly urbanizing areas of northern Peru due to their low load-bearing capacity, high moisture sensitivity, and progressive stiffness degradation under cyclic traffic loading. This study evaluates the sustainable stabilization of such soils through the partial substitution of natural clay with sawdust treated with citric acid (STCA), a lignocellulosic residue modified to enhance soil–fiber interaction. The treated sawdust exhibited a natural moisture content of 43.36% and a specific gravity of 1.93. The material was chemically treated by immersion of 25 kg of sieved sawdust in a 5% (w/v) citric acid solution for 24 h to promote surface esterification between hydroxyl groups of cellulose fibers and carboxyl groups of citric acid, followed by oven drying at 60 °C until constant mass. The experimental program comprised physicochemical characterization of STCA, preparation of soil–STCA mixtures at 1, 3, 5, and 7% substitution levels, mechanical evaluation using Modified Proctor compaction and California Bearing Ratio (CBR) tests, and microstructural analysis through SEM–EDS. The optimum mixture (95US:5STCA) resulted in a 12.31% reduction in maximum dry density, a 19.67% increase in optimum moisture content, and a 139.82% improvement in CBR compared with untreated soil. SEM–EDS observations indicate that STCA fibers encapsulate clay aggregates and promote physicochemical bonding, forming more stable granular structures. These findings demonstrate that STCA provides a technically viable and environmentally sustainable alternative for subgrade stabilization in low-volume road construction under tropical and semi-arid conditions. © Springer Nature Switzerland AG 2026.

Instituciones: Universidad Señor de Sipán