The escalating environmental challenge posed by plastic waste accumulation necessitates innovative and sustainable solutions within civil engineering. This study investigates the feasibility of utilizing a novel, custom-engineered waste plastic aggregate, derived from post-consumer waste, as a partial replacement for conventional coarse aggregate in an asphalt mixture. The primary objective is to determine the viability of this approach and quantify the impact of the plastic aggregate on the fundamental mechanical and volumetric properties of the asphalt. The methodology involves systematically incorporating the waste plastic aggregate at varying percentages and employing the Marshall mix design method to assess key performance indicators. Critical parameters such as Marshall stability, flow, Marshall quotient, and volumetric properties are determined. The full experimental results comparing the performance of the waste-plastic-aggregate-modified mixtures against the conventional control mix are currently being finalized. Key findings on Marshall stability, flow, Marshall quotient, and volumetric properties will be quantified and presented in detail at the conference, highlighting the performance trade-offs and benefits at different replacement percentages. This study will establish the feasibility of using custom-engineered waste plastic aggregates in asphalt mixtures. It is anticipated that the findings will offer crucial data for developing lighter, more resource-efficient, and environmentally friendly pavement materials. This work aims to advance circular economy principles by providing a viable, large-scale application for non-biodegradable plastic waste in sustainable construction.