Experimentally investigating performance & durability of open-graded high-drainage asphalt paving mixes prepared with 100% reclaimed asphalt pavement material by cold mixing

This study aims to investigate the performance characteristics of high-drainage asphalt paving mixes fully prepared by recycling Reclaimed Asphalt Pavement (RAP) materials with the cold mixing technique. Asphalt mixtures prepared with 100% RAP (RAPM) and traditional aggregates (TAM), with open-graded aggregates size distribution, were subjected to various experimental tests, such as air voids content, indirect tensile strength (ITS), and stiffness modulus tests under wet conditions. Findings show that the air void content of RAPM was 12–15%, which is more than TAM (7–8%). Also, the permeability of RAPM (6.4 × 10⁻⁴ m/s) is higher than TAM (4.6 × 10⁻⁴ m/s). Air voids and permeability indicate higher interconnection of pores and improved drainage capacity in RAPM than in TAM. However, TAM was shown to be less moisture sensitive and possess higher ITS. Moreover, RAPM had a particle loss of about 63–70%, which is significantly higher than TAM (12–17%) in the Cantabro test under wet conditions. The ITS values of TAM averaged around 1.3 MPa (dry) and 1.07 MPa (wet) were higher than the averaged values of RAPM (0.25 MPa (dry) and 0.16 MPa (wet)). The mean values of the ITS ratio for TAM and 100% RAPM were 81% and 61%, respectively. The average values of Indirect Tensile Stiffness Modulus (ITSM) at 5℃, 20℃, 35℃ for traditional and 100% RAP were 13,436, 4549, 1209 MPa, and 4295, 1791, 605 MPa, respectively. According to these results, RAPM would be a better alternative in urban areas affected by heavy rainfall due to better drainage capacity. Moreover, RAPM exhibits potential portfolio sustainability benefits. However, there is much to be done to increase RAPM performance and devise advanced formulation techniques to realize its potential.