Feasibility Study of Utilizing Microplastic in 100 % Reclaimed Asphalt Pavement Mixture Using Warm Mix Asphalt Additive

ABSTRACT The increasing demand for sustainable construction materials has led to significant advancements in asphalt pavement technology. This study explores the incorporation of three types of microplastics—recycled polypropylene, recycled high-density polyethylene (HDPE), and repurposed low-density polyethylene (LDPE)—at dosages of 0.3 %, 0.6 %, and 0.8 % into 100 % reclaimed asphalt pavement (RAP) with the addition of the warm mix asphalt additive, Evotherm P25. A comprehensive evaluation was conducted through laboratory tests, including the indirect tensile cracking test (IDEAL-CT), ideal shear rutting test (IDEAL RT), Cantabro loss test, and moisture susceptibility test, to assess the mechanical and durability performance of the modified asphalt mixtures. The results demonstrated that microplastics enhanced the cracking tolerance index but reduced the workability, particularly in HDPE-modified mixtures. Similarly, LDPE showed improved volumetric properties due to its melting behavior during mixing but resulted in higher mass loss in the Cantabro loss test. Although HDPE improved rutting resistance, increasing plastic dosages adversely affected rutting performance. The moisture susceptibility test revealed tensile strength ratio values below the standard threshold of 80 % for all samples, indicating low resistance to stripping. These findings provided insight into modifying 100 % RAP with microplastic as a potential pothole-repairing material or other low-risk asphalt applications.