The Gedebage region faces a myriad of challenges, including road deformations, swelling of roads and bridges, and cracks in drainage foundations, buildings, and asphalt concrete. To address these issues, a comprehensive analysis of soil physical properties was conducted at the POLBAN soil mechanics laboratory, along with chemical tests at the POLMAN laboratory. The primary objective was to understand the physical properties and mineral composition of Gedebage soil and develop effective soil management strategies. Soil stabilization was employed as a method to enhance infrastructure resilience in Gedebage. Marble powder waste (MPW) was utilized in varying concentrations (2.5%, 4%, 5.5%, and 7%) along with 4% phosphoric acid (PA) to optimize the solution. MPW filled soil pores and improved cohesion, while PA reduced moisture content, enhanced particle bonding, increased load-bearing capacity, and minimized soil volume changes. Initial soil tests revealed a high plasticity index (PI) of 54.20%, indicating Gedebage, expansive clay soil nature with significant potential for expansion and plasticity. The AASHTO classified it as "A-7-6", and the USCS classified it as "CH." Stabilization experiments demonstrated that the most effective combination was the original soil + 7% MPW + 4% PA, resulting in a PI of 16.03% and an activity level (Ac) of 0.48. AASHTO classified this combination as "A-2-6," and the USCS as "CL." Furthermore, MPW oxygen, silica, and aluminum content exhibited potential for pozzolanic reactions, while PA reacted with soil mineral cations likes: Ca, Fe, Al dan Phosphor, forming a water-resistant layer. MPW and PA effectively improved the expansive clay soil's ability to withstand moisture-induced changes. This study serves as a foundation for further investigations into the mechanical properties of Gedebage soil, focusing on bearing capacity and stability, using MPW and PA in civil and infrastructure foundation applications.