The EXPERIMENTAL STUDY OF AGGREGATE GRADITION VARIATIONS ON MARSHALL CHARACTERISTICS OF PP PLASTIC MODIFIED AC-WC ASPHALT MIXTURE

Abstract

This study evaluated the effect of aggregate gradation variations on the volumetric and Marshall characteristics of AC-WC asphalt mixtures with the addition of polypropylene (PP) plastic waste. Two types of aggregate gradations were used, namely fine gradation and coarse gradation, with variations in PP plastic content of 0%, 1%, 2%, 3%, and 4% of the total weight of the mixture. Tests were conducted to determine volumetric parameters including Void in Mix (VIM), Void in Mineral Aggregate (VMA), and Void Filled with Bitumen (VFB), as well as Marshall parameters such as stability, flow, and Marshall Quotient (MQ). The results showed that the addition of PP plastic can increase the stability and MQ of the mixture up to an optimum level of around 3%, after which it tends to be stable or slightly decrease. Fine gradation provides better performance than coarse gradation, indicated by lower VIM values, higher VFB, and smaller flow so that the mixture is denser and more resistant to deformation. The VMA value at fine gradation remains within the recommended range of Bina Marga specifications, supporting optimal asphalt density and distribution. A fine-graded AC-WC mixture with a PP plastic content of 2–3% is recommended because it meets the volumetric and Marshall criteria according to Bina Marga standards for heavy traffic. This study recommends further testing, including long-term durability tests and economic and environmental analyses to support the implementation of the use of PP plastic waste in sustainable road pavement construction.