Design and Evaluation of Asphalt Concrete Incorporating Plastic Aggregates Fabricated Using 3D Printing Technology.

Environmental protection and sustainability have been a serious challenge due to the excess amount of waste plastic, and the inefficient methods of its disposal. This study aims at exploring the feasibility of using plastic material in asphalt concrete followed by the design and evaluation of modified asphalt mix. Four different types of asphalt mixtures were made by mixing mineral aggregates with plastic aggregates of different shapes and sizes. The conventional dense-graded asphalt concrete incorporating mineral aggregates was selected as control material, whereas the other three types of asphalt mixtures were produced by substituting 3D-printed plastic aggregates for mineral aggregates. Marshall characteristics were utilized to evaluate the volumetric and mechanical properties of the asphalt mixtures. Test results show that the asphalt mixture containing solid plastic aggregate appears to have a 14.3% reduction in bulk density, thereby potentially reducing the haul costs. Due to the angular shape of the aggregate, the stability for the asphalt mixture containing the 3D-printed aggregate is 1.95 times higher than that for the asphalt mixture incorporating all mineral aggregates. The addition of the plastic printed aggregate enhances the strain capacity to achieve failure of the asphalt mixture. However, caution should be taken when incorporating the hollow or fine printed aggregates into the asphalt mixture due to their variation of volumetric properties.