Civil and Environmental Engineering
First Advisor
Jamilla Emi Sudo Lutif Teixeira
Committee Members
Jiong Hu, Nirupam Aich
Date of this Version
7-2025
Document Type
Thesis
Citation
A thesis presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillment of requirements for the degree of Master of Science
Major: Civil Engineering
Under the supervision of Professor Jamilla Emi Sudo Lutif Teixeira
Lincoln, Nebraska, July 2025
Abstract
Incorporating waste plastic (WP) into hot mix asphalt (HMA) offers a promising approach to enhance recycling rates and improve asphalt concrete (AC) performance, particularly in moisture damage resistance. However, results vary widely due to differences in WP types, sizes, and mixing methods. The lack of standardized procedures, especially for the dry process, has led to inconsistent integration and unclear roles of WP in AC mixtures. Studies suggest that introducing WP to pre-heated aggregates at temperatures exceeding its melting point can enhance mixture resistance to rutting, cracking, and moisture damage. In this context, this study was conducted in two phases to evaluate the feasibility and implementation of WP-modified asphalt. Phase 1 focused on WP selection and characterization, development of a laboratory mixing protocol, performance testing, and evaluation of bonding characteristics at the binder-aggregate interface. Three mixtures were examined: a control mix, and two polypropylene-modified mixes (AC-PP-MM1 and AC-PP-MM2) with 1% WP and different pre-heating temperatures. The Hamburg Wheel Tracking Test (HWTT) and Indirect Tensile Asphalt Cracking Test (IDEAL-CT) were used to evaluate mechanical performance. Results showed that higher mixing temperatures improved polypropylene melting and aggregate coating, enhancing rutting and moisture damage resistance. The study also compared the effects of two WP types (LDPE and PP). Both improved moisture damage resistance, with LDPE showing superior performance. WP incorporation enhanced binder-aggregate bond strength, reduced water wettability, and increased compatibility. However, PP-modified mixes exhibited poor cracking resistance based on IDEAL-CT results. Phase 2 assessed the practical implementation of a Nebraska Superpave Recycled Mixture (SPR NDOT) with WP in South Sioux City, NE. Laboratory results indicated that combining Reclaimed Asphalt Pavement (RAP) and 1% LDPE improved moisture and rutting resistance. Lower RAP contents resulted in softer mixes with better cracking performance. A mix of 25% RAP and 1% LDPE was plant-produced and field-implemented for performance monitoring. Future works will compare laboratory and plant-produced mixes to validate whether the lab-developed procedure is scalable for full-scale asphalt production.
Advisor: Jamilla Emi Sudo Lutif Teixeira
Comments
Copyright 2025, Isabella Madeira Bueno. Used by permission