Performance Evaluation of Marine Clay Subgrade Stabilized with Industrial Wastes and Reinforced Using Reclaimed Rubber Cell Mattress

India’s expanding transportation infrastructure requires construction of pavements over weak subgrade soils such as marine clay, which exhibit low strength, high compressibility, and significant moisture sensitivity. This study evaluates the feasibility of utilizing industrial waste materials—marble dust (MD), quarry dust (QD), fly ash (FA), bagasse ash (BA), and granulated blast furnace slag (GBFS)—for subgrade and sub-base stabilization in flexible pavement systems. Laboratory investigations including Atterberg limits, Standard Proctor compaction, California Bearing Ratio (CBR), Unconfined Compressive Strength (UCS), and triaxial shear tests were conducted in accordance with relevant IS and IRC specifications. The optimum subgrade stabilization mixes were identified as 20% MD + 4% lime and 25% QD + 6% lime, producing increases of 143% and 460% in soaked CBR, respectively. For sub-base applications, a mix of 60% FA + 40% GBFS exhibited superior strength, stiffness, and permeability characteristics comparable to conventional granular sub-base materials. Model pavement studies performed on unreinforced, geogrid-reinforced, and reclaimed rubber cell mattress (RRCM)-reinforced sections demonstrated enhanced load-deformation behavior and significant stress reduction at the subgrade–sub-base interface. The results confirm that integrating industrial waste materials and reinforcement layers improves the structural performance and durability of pavements while promoting sustainable and cost-effective highway construction.