Date of Award

Spring 2026

Abstract

Asphalt makes up about 94% of the pavements in the United States which are required to withstand traffic demands and environmental conditions throughout their service life. These pavements are susceptible to aging which leads to increased stiffness and brittleness making them prone to low and intermediate temperature cracking. Currently, Balanced Mix Design (BMD) sets performance targets aiming to mitigate cracking and rutting distresses. It also allows for the use of innovative materials such as additives, which may be used to modify the asphalt binder behavior to meet specific performance targets. Although numerous studies have examined several types of additives, few provide a comparison of the long-term fracture properties. This thesis evaluates a total of 27 mixtures, containing nine types of additives which include PMA, fibers, rubber, plastic, and recycling agents (RA). Laboratory loose mixture aging was performed to simulate field aging conditions. The low temperature fracture properties were measured using the Disk-Shaped Compact Tension test (DCT) while the intermediate temperature fracture properties were measured using the Indirect Tensile Asphalt Cracking test (IDEAL-CT) and Illinois Flexibility Index Test (I-FIT). Statistical analyses were performed and included analysis of variance (ANOVA), Tukey Kramer HSD and aging indices to evaluate performance property trends across aging conditions and the influence of aging. Additive performance properties varied by test method and aging severity. Both dry plastic and dry rubber exhibited moderate low temperature fracture energy indicating low temperature flexibility Fiber modified mixtures generally showed strong intermediate temperature performance properties, indicating effective crack bridging behavior. Discrepancies between IDEAL-CT and I-FIT fracture properties may be attributed to differences in test setups and specimen geometry. RAs did not consistently improve long-term fracture properties. Overall, no single additive consistently had high performance properties across the fracture tests, showing that additive effectiveness is dependent on aging severity and the specific cracking mechanism considered. These results contribute to improved understanding of long-term additive performance properties and support informed material selection for durable asphalt pavement design.

Document Type

Master's Thesis

First Advisor

Jo E. Sias

Second Advisor

Jo E. Sias

Third Advisor

Eshan V. Dave

Degree Name

Master of Science

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