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Title:Non-destructive quantitative assessment of oxidation in aged and rejuvenated asphalt concrete pavements using a non-collinear wave mixing approach
Author(s):McGovern, Megan E
Director of Research:Reis, Henrique
Doctoral Committee Chair(s):Reis, Henrique
Doctoral Committee Member(s):Buttlar, William G.; O'Brien, William D.; Sreenivas, Ramavarapu S.; Thompson, Marshall R.
Department / Program:Industrial&Enterprise Sys Eng
Discipline:Systems & Entrepreneurial Engr
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Non-collinear wave mixing
Nonlinear acoustics
Asphalt pavements
Oxidative aging
Non-destructive testing
Damage characterization
Quantitative assessment
Abstract:Oxidative aging in asphalt concrete pavements is one of the chief contributors to pavement degradation. Oxidation contributes to the formation of a diffuse micro-flaw population in the mastic. This damage is primarily concentrated at the top (surface) of the pavement, where exposure to oxygen is the greatest. These flaws serve as the nuclei to crack formation and propagation, and adversely affect the pavement's structural integrity. It is more cost effective to perform maintenance when the pavement contains relatively little damage, than it is to defer maintenance until more drastic measures must be taken. Currently, engineers lack the proper tools for non-destructive, quick, and reliable inspection. The work in this report addresses this need by employing non-collinear wave mixing, a nonlinear acoustic technique, to evaluate the level of oxidation of the pavement. To implement the nonlinear technique, the linear acoustic parameters, i.e., dilatational and shear velocities and attenuations, of asphalt concrete specimens with various levels of oxidative aging were characterized. In non-collinear wave mixing, two waves are propagated so that they cross paths. Under the right conditions, these two waves will interact to produce a third wave. Taking advantage of critically refracted longitudinal waves enabled the non-collinear wave mixing measurements to be taken from the pavement surface. Two nonlinear parameters were measured as a function of oxidative aging: the efficiency of interaction, β/β0 , and the frequency at which the interaction takes place, ƒ2/ƒ1. A nonlinear damage characterization curve was introduced, which is generated for a particular mixture under laboratory conditions, by plotting β/β0 versus ƒ2/ƒ1 for various levels of oxidative aging. Field pavement measurements of (β/β0, ƒ2/ƒ1) can then be referenced against the nonlinear damage characterization curve to evaluate the state of the pavement. The testing set-up was configured to be one-sided, hence truly non-destructive, via the use of these subsurface waves. Two data-collection approaches are presented, which can be used even if the linear acoustic properties are unknown a priori, for practical field implementation. The efficacy of an asphalt rejuvenation product was also studied using this technique. Pavement engineers can thus continuously monitor the pavement and make decisions (such as the application of rejuvenators) to prolong its service life.
Issue Date:2016-07-06
Rights Information:Copyright 2016 Megan E. McGovern
Date Available in IDEALS:2016-11-10
Date Deposited:2016-08

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