Reclaimed asphalt pavement (RAP) is being recognized as a valuable waste material, offering a solution to address the challenges of pavement recycling and enhance environmental sustainability in transportation infrastructure. The purpose of this research is to assess the performance of hot mix asphalt obtained from disintegrated existing asphalt pavement. This paper deals with the evaluation of the mechanical properties of bitumen mixtures incorporating RAP and expanded polystyrene (EPS) as sustainable alternatives. Marshall testing was conducted to evaluate the flow values and stability of the mixtures on twelve bitumen samples with varying RAP percentages (30%, 50%, and 70%) and individual bitumen percentages (3.5%, 4%, 4.5%, and 5%). Results show that a 70% RAP mixture with 4% bitumen exhibits superior stability, achieving a Marshall stability of 14.76 kN. Additionally, the inclusion of EPS in different proportions (3%, 4%, and 5%) improved mechanical properties and optimum stability of 15092.06 KN-specific EPS percentages at 5%. This study emphasizes the advantages of incorporating RAP and EPS into bituminous mixtures, thereby fostering sustainable pavement construction by recycling waste materials and reducing costs.