Mechanical and numerical evaluation of expansive soils for flexible road pavement stabilization using sugarcane bagasse ash and lime

The expansive, highly swelling clay soils, which have low bearing capacity, result in damage to flexible pavements. Utilizing locally available waste materials to develop low-cost, sustainable stabilizers improves the engineering properties of the subgrade. Laboratory-strength enhancement, establishing links between material-level stabilization and structural response via numerical modeling, has become a landmark. This study aims to assess the combination of sugarcane bagasse ash (SCBA) with lime as a remedial measure for expansive soil and its effect on flexible pavement performance. Out of six soil samples, for two critical samples (P1 and P4), the index property and soaked California Bearing Ratio (CBR) test were performed on both untreated and stabilized soils using different proportions of SCBA-lime, due to their more severe behavior compared to the other samples. The best mix was introduced to a 3D finite element model (FEM) to determine critical stresses and strains. The soaked CBR values of untreated soil samples P1 and P4 were 1.90% and 2.12%, respectively; however, these values increased to 14.50% and 13.40% after stabilization with 1% SCBA and 4% lime. Corresponding resilient modulus was improved from 20.77 MPa to 144.17 MPa. Results from FEM have shown a notable reduction of about 4.9% in the horizontal tensile strain (HTS) at the base of the asphalt layer and 5.9% in the vertical compressive strain (VCS) at the top of the subgrade. The study reveals that the strength and pavement performance of the SCBA–lime stabilized subgrades can be enhanced significantly, which is a sustainable practice for the mechanistic application of expansive soil subgrade.