Satheesh, A.Sridhar, S.2026-02-032025International Journal of Geosynthetics and Ground Engineering, 2025, 11, 2, pp. -21999260https://doi.org/10.1007/s40891-025-00626-xhttps://idr.nitk.ac.in/handle/123456789/20366Lithomargic soil, extensively found along the coastal regions of Karnataka, India, is inherently weak with a low California Bearing Ratio (CBR) value and hence, unsuitable as a subgrade or sub-base material in a pavement. To utilize the lithomargic soil as a subgrade or sub-base material, the present study focuses on its stabilization using Iron Ore Tailing (IOT) and cement. IOT, collected from Kudremukh region, Karnataka, India, was assessed for its suitability in pavement stabilization, with proportions ranging from 10 to 50%. Lithomargic soil stabilized with optimum proportion of IOT was subsequently treated with cement, with proportions ranging from 2 to 12% and in increments of 2%. Compaction test, CBR test, Unconfined compression test and durability tests were carried out on lithomargic soil stabilized by IOT alone and both IOT and Cement. Furthermore, X-ray Diffraction, Field Emission Scanning Electron Microscope and Fourier Transform Infrared Spectroscopy analyses were carried out to understand the stabilization mechanisms. Optimal results were obtained for lithomargic soil treated with 20% IOT. The unconfined compression test revealed that the soil-IOT mix satisfied the strength requirements for a subbase material with 6% cement, whereas lithomargic soil alone required 8% cement content to meet the strength requirements. Incorporating 2% cement into the soil-IOT mix enhanced the CBR to 31%, up from 2% for lithomargic soil, satisfying subgrade requirement. All stabilized mix containing more than 2% cement met the durability requirements for 12 cycles of wet-dry and freeze-thaw. The microstructural analyses showed cementitious compounds within the soil structure, indicating the formation of hydration products along with additional hydroxyl compounds. The pavement design and analysis for high-volume roads was carried out as per IRC: 37-2018 and IITPAVE software and results indicate 28% reduction in design pavement thickness and a reduced maximum deflection value after stabilization. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2025.CompactionDesign for testabilityDynamic responseIron ore reductionIron ore treatmentOre tailingsSoil cementSoil structure interactionsSoil testingBase materialCalifornia bearing ratioComprehensive evaluationEngineering behaviorFlexible pavementsIron ore tailingsKarnatakaLithomargic soilSub-basesUnconfined compression testsCompression testing