Date of Award

8-2011

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Civil Engineering

Advisor

Putman, Bradley J.

Committee Member

Burati , James L.

Committee Member

Juang , C. Hsein

Committee Member

Rangaraju , Prasada Rao

Abstract

Asphalt pavements are composed of three components: aggregate, asphalt binder, and air. In the process of plant production and on-site construction, the construction quality can vary in the three component and the variability can further affect a pavement's future performance.. This research identifies aggregate gradation, binder content, and air voids content as the fundamental parameters. Understanding the fundamental parameters' influence on the HMA mixture's performance properties can provide valuable information on how to improve the current quality insurance practice. The objective of this study is to conduct well-controlled experiments to investigate how mix gradation, air voids and small range binder content deviation from design binder content can affect the performance properties of asphalt concrete.
In this study, three aggregate sources were utilized, and two gradations (fine-graded and coarse-graded) were tested from each aggregate source. Two levels of binder content and air voids content were used to represent the construction variability levels of binder content and density, respectively. The three aspects of mixture performance that were evaluated include rutting, tensile cracking and moisture susceptibility.
It is found that aggregate gradation is significant to rutting and IDT performance. In rutting, the gradation effect is aggregate specific. The effect of gradation on ITS can be reflected by the design binder content, which is closely related to the VMA value of the aggregate gradation. Therefore, the rutting performance seems more sensitive to gradation variation than the tensile strength of a mixture. Binder content variation in a permissible range can statistically affect the rutting and IDT strength performance. A 'binder content window' is determined from a fracture energy point of view; however, the rutting performance should not be compromised. On pavement density variation, the study showed that reducing air voids content can increase the mixtures' engineering properties, both rutting and ITS.
Several statistical regression models were developed using the fundamental parameters. The equations can effectively summarize the experimental data set, creating quantitative relationships that can be used to predict the response variables.

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