Semester

Fall

Date of Graduation

2020

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Civil and Environmental Engineering

Committee Chair

John Zaniewski

Committee Member

Fei Dai

Committee Member

YooJung Yoon

Abstract

Asphalt concrete is one of the main ingredients used in the paving of roadways across the globe. These roadways have been deteriorating from overuse, under design, and a lack of understanding of the engineering properties. In the asphalt community, it is agreed upon that polymer modifiers and aggregate size have comparable impacts on the performance of a pavement, such as, low creep at high temperatures, high ductility at low temperatures, high toughness, resistance to moisture and temperature, high cohesive and adhesive strength. With all of these advantages, it has been often assumed that polymer modifiers extend/improve the expected life of pavements. Currently, test methods to accurately predict performance of a pavement based on binder type and aggregate size have not been widely accepted in the pavement design community. This research aimed to evaluate the effect of polymer modifiers and aggregate size on the performance of a pavement, specifically the modulus and fatigue properties.

Six different hot-mix asphalt mixtures were evaluated in this research that were combinations of three (3) binder types; a PG 70-22, PG 70-22 Polymer Modified (PM), and PG 76-22 PM and two (2) different nominal maximum aggregate sizes (NMAS); 9.5 mm and 12.5 mm. Prior to testing the samples for their performance properties. three methods of measuring bulk specific gravity were used to evaluate air distribution within the samples: Saturated Surface-Dry, CoreLok, and Dimensional (volumetric mass density).

Finally, to evaluate samples for performance properties the Asphalt Mixture Performance Tester (AMPT) was utilized. The AMPT is a relatively new method to measure the performance of a mixture by measuring fatigue, dynamic modulus, and flow number. Only fatigue and dynamic modulus were measured in this research. To evaluate the data collected from the AMPT, both the Mastersolver Version 2.2 developed by Bonaquist and Asphalt Pavement Hierarchical Analysis Toolbox – Fatigue Program (Alpha-FatigueTM software) developed by Kim were used.

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