Evaluation of Recycled Plastics in Asphalt Mixtures
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Authors
Larios Rodriguez, Julissa Jasmin
Issue Date
2025
Type
Dissertation
Language
en_US
Keywords
Asphalt Mixtures , Fibers , Pavement , Reclaimed Asphalt Pavement , Recycled Plastics , Sustainability
Alternative Title
Abstract
This study investigates the feasibility of incorporating Modified Post-Consumer Plastic (MPCP) as a performance-enhancing additive in asphalt mixtures. Two phases of laboratory testing and analysis were conducted to evaluate the rheological, mechanical, and economic impacts of MPCP modification compared to traditional control and fiber-modified mixtures.In Phase I, asphalt binders were modified with 10% and 20% MPCP by weight of binder, and their effects on binder properties and mixture performance were evaluated. The 10% MPCP dosage showed improved high-temperature rutting resistance with limited elastic benefit, while the 20% dosage resulted in phase separation and poor low-temperature performance. Mixtures containing 20% and 40% Reclaimed Asphalt Pavement (RAP) were tested for cracking (CTindex), rutting (HWTT), dynamic modulus, and moisture susceptibility. The results revealed that MPCP increased mixture stiffness and improved rutting resistance, but often reduced cracking resistance, particularly in 20% RAP mixtures.
Phase II focused on optimizing MPCP performance by pairing it with a softer base binder (PG 58-28) at 10% dosage and evaluating mixtures containing 20% RAP. A comprehensive set of tests, including Ideal-CT, HWTT, dynamic modulus, flexural fatigue, flow number, and mechanistic-empirical (M-E) modeling, was used to assess cracking and rutting performance. The PG 58-28 MPCP (L) mixture demonstrated comparable cracking and rutting resistance to PG 64-22 Control, and significantly improved fatigue life in thin pavement structures (3-inch AC) under low and high-speed conditions. However, the benefits diminished in thicker pavements (6-inch AC), where the stiffer control mixture showed better resistance to rutting and lower life-cycle costs under braking loads. Additionally, the PG 64-22 Fiber mixture surpassed the other mixtures in rutting resistance but exhibited comparable fatigue resistance to the PG 64-22 Control.
Life-cycle cost analysis (LCCA) indicated that MPCP mixtures offer economic advantages in applications where fatigue performance is critical. These findings suggest MPCP is best suited for pavements with thin asphalt layers or where cracking is the primary mode of distress regardless of speed or braking conditions (10 mph with braking and 60 mph without braking) as simulated for the mechanistic-empirical analysis in this study.