Laboratory Performance Evaluation of Hot Mix Asphalt Mixtures With Incorporations of Different Recycled Plastic Additives Using the Dry Method

Asphalt pavements are susceptible to distresses such as cracking, rutting, and moisture damage, which reduce service life and increase maintenance costs. This study evaluated the use of recycled materials from HDPE and LDPE plastics (shredded and pelletized) and PET fibers of two lengths as asphalt mixture additives to provide a sustainable approach to improve performance. The materials were incorporated into two control mixtures designed with the Balanced Mix Design (BMD) method. Laboratory testing assessed cracking and rutting resistance, moisture susceptibility, abrasion resistance, and dynamic modulus across a range of conditions. Results showed that PET fibers improved cracking resistance due to a reinforcement effect during crack formation. In contrast, plastics, particularly LDPE, significantly increased stiffness and rutting resistance but reduced cracking resistance. The addition of either plastics or fiber also improved abrasion and moisture resistance. Dynamic modulus tests confirmed that plastics increased the stiffness of the mixture, while fibers provided a more flexible response. Combinations of the additives exhibited that the stiffening due to plastics affected the mixture performance, limiting the benefits of fibers and reducing the feasibility of using HDPE and LDPE to improve the overall asphalt concrete behavior. In addition, fiber-reinforced mixtures at lower binder contents still met performance thresholds, showing potential for cost savings. Overall, recycled plastics enhance rutting resistance, while PET fibers offer a promising solution to improve cracking resistance in asphalt mixtures.