Date of Award

2019

Document Type

Campus Access Dissertation

Degree Name

Doctor of Philosophy in Civil Engineering (PhD)

Administrative Home Department

Department of Civil and Environmental Engineering

Advisor 1

Zhanping You

Committee Member 1

Jacob Hiller

Committee Member 2

Qingli Dai

Committee Member 3

Song-Lin Yang

Abstract

Water in the asphalt pavement is highly concerning, as it often causes the debonding between asphalt film and aggregate surface or early rutting/fatigue cracking because of reduced mix strength. Moisture transport is the processes that occurs when moisture in liquid or vapor state infiltrates the asphalt binder, through the interface of binder-aggregate, and the asphalt mixture.

This dissertation investigated the water permeability of asphalt mixtures in vertical direction, and effect of moisture conditioning on asphalt mixtures. Additionally, relationships between coefficient of permeability, porosity, and air void content of fine-graded hot-mix asphalt were studied. The coefficient of permeability increases as the air void and porosity values increase. After the second moisture conditioning, it was observed that specimens have a reduced porosity and coefficient of permeability.

In addition, this dissertation predicted the coefficient of permeability of asphalt mixtures using the Lattice Boltzmann Method (LBM). The numerical method was verified by simulating fluid flow in Poiseuille flow, parallel tubes, and sandstone samples. The experimental results and simulation results were very similar. The LBM can be a powerful tool to understand the fluid flow in asphalt mixtures.

Coefficients of permeability in three different directions (longitudinal, transverse and vertical direction) were also studied. The studied asphalt mixtures were isotropic in two horizontal directions (x- and y- directions) and anisotropic comparing horizontal and vertical directions. The coefficients of permeability in horizontal directions were about two times than that in vertical direction.

Image analysis techniques were used to analyze X-ray CT images of asphalt mixtures and obtain their effective percent air voids, average void diameter, Euler number, degree of anisotropy, specific surface area, and tortuosity. Pearson’s correlation coefficients were used to evaluate the correlation between the selected parameters. The air void content, connected air void, and average void diameter were highly correlated with the coefficients of permeability, which were valuable to understand the fluid flow properties in asphalt mixtures.

Available for download on Wednesday, November 25, 2020

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