Date of Graduation

5-2024

Document Type

Thesis

Degree Name

Master of Science in Civil Engineering (MSCE)

Degree Level

Graduate

Department

Civil Engineering

Advisor/Mentor

Braham, Andrew F.

Committee Member

Hall, Kevin D.

Second Committee Member

Sasidharan, Lekshmi

Keywords

Asphalt; Balanced Mix Design; Cracking; Rutting; Statistical Analysis

Abstract

Many state agencies recognize that their current asphalt mixtures are susceptible to cracking and poor durability. Some agencies are adjusting their mix design procedures to increase the asphalt binder content, while others are moving toward a balanced mix design (BMD) to try and address both cracking and rutting. However, there is uncertainty on what asphalt mixture properties can impact cracking and rutting. This research explores the IDEAL-CT and APA data from two years of mix designs collected by ARDOT. To understand which asphalt mixture properties impact cracking and rutting in the field, Pearson correlation (PCM), Spearman rank correlation (SCM) and Kendall’s Tau (KCM) analysis methods were used. After running these analysis methods, CTIndex had the highest correlation with film thickness, while the rut depth had the highest correlation with the upper asphalt binder grade across all three. Interestingly, the second highest correlation was volumetric, with VFA or air voids for CTIndex and VMA or air voids for rut depth. As a part of this analysis, a preliminary recommendation for a minimum 9 microns asphalt film thickness has been made to ensure mixture durability. Finally, a procedure is provided for other owners to examine how their asphalt mixture properties impact their performance tests. Based on this research it is not recommended to use KCM, as it had the lowest correlation values. Both the PCM and SCM methods are recommended for use.

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