Polyethylene Terephthalate (PET) is one of the most commonly available kinds of plastic present in the municipal solid waste and it is a non-biodegradable semi-crystalline thermoplastic polymer, studied as polyester material. This paper intends to assess impacts of using PET (regular and irradiated) as aggregate that would replace by volume of equal size (10.00-5.00mm) in asphalt blend on the engineering properties of dense graded asphaltic concrete. The volumetric and mechanical properties of the blends incorporating different percent of PET (0, 5, 10, 15 and 20) were determined. In all mixtures, 5.0 optimum bitumen content was utilized. The outcome revealed that aggregate substitution of 10 (equivalent to 2.4 by weight of total mix) with irradiated PET result in optimum Marshall Stability and flow value of 3.6mm. It also showed that mixes with irradiated PET at 100kGy radiation dose have Marshall Stability values higher than mixes with same contents of regular PET. The finding also shows that the addition of PET and utilization of gamma radiation has a critical constructive outcome on the properties of asphalt concrete mixes as the stability increases for mixes with irradiated PET when compared with mixes with regular PET (RPET). © 2020 IOP Publishing Ltd. All rights reserved.