The growing use of trucks for freight transportation is causing significant damage to motorway pavements, making pavement rehabilitation crucial for extending their lifespan. To address this issue, this study proposes the use of reclaimed asphalt pavement (RAP) material, fly ash, and cement in varying proportions in sub-base as a sustainable approach. The study evaluates the strength characteristics of the pavement during rehabilitation and estimates the percentage of recycled material used. A laboratory investigation was conducted, and the results show a significant improvement in the strength of the pavement. The optimal percentage of RAP as replacement in HBG aggregate was found to be 30%, in combination with 25% fly ash and 5% cement. Thus, the study presents an alternative combination of sub-base materials, emphasizing sustainability. This approach can potentially reduce costs and effort while mitigating the damage caused by freight vehicles to motorway pavements.