Resumen
We often use the plastics daily, containing of polyethylene plastic polymers which recently can be utilized as additional material for road pavements. Several studies have attempted to find the optimum proportion of an asphalt mixture using modified Asbuton which is local bitumen abundantly deposited in Buton Island Indonesia, added with plastic waste. The optimum proportion of the asphalt mixture is influenced by many factors, such as the interactions of the material component in the asphalt mixture. To obtain the optimum proportion based a single factor, many studies employ statistical methods. This study aims to determine the optimum proportion for the asphalt mixture of the modified Asbuton with PET plastic waste by using a Response Surface Methodology (RSM). The employed RSM is the Expert Version 12 design (Stat-Ease, Inc., Minneapolis, MN, USA, 2020), in which the statistical modeling based on Box Behnken Design (BBD) and three factorial levels. The results obtained in this study show that the RSM optimization could achieve the asphalt mixtures characteristics including the stability, Marshall Quotient (MQ), Void in MIX (VIM), Void Mineral Aggregate (VMA) and density, in the level of satisfying the specification requirements of Ministry of Public Works of Indonesia. The optimum stability is at 2002.72 kg, fulfilled the minimum density of 800 kg. For the MQ, the optimal point of MQ is 500.68 kg/mm, satisfied the minimum the MQ standard minimum of 250 kg/mm. In addition, the optimal VIM is at 3.40%, satisfying the VIM specifications in the range of 3?5%. The optimal VMA response is at 21.65%, which is also satisfied the VMA specification, 15%.