Author(s)

Luis Gaitan

Date Approved

11-22-2012

Document Type

Thesis

Degree Name

M.S. Engineering

Department

Civil and Environmental Engineering

College

Henry M. Rowan College of Engineering

First Advisor

Mehta, Yusuf

Subject(s)

Pavements, Asphalt;Roads--Design and construction

Disciplines

Civil and Environmental Engineering

Abstract

The paving industry in recent years has seen the emergence of a plethora of warm mix asphalt (WMA) technologies and application. With most states incorporating a recycled asphalt pavement (RAP) limit, it is necessary for WMA to not only serve as a greener technology but to work in conjunction with current RAP practices. Presently, most agencies assume a full blending condition in their mixtures which may lead to under asphalted mixtures. The purpose of this study is to develop a methodology for quantifying the degree of blending that occurs in WMA RAP mixtures at higher percentages of RAP. In addition to the methodology, the degree of blending will be determined for WMA and HMA production temperatures as well as other varying pre-paving conditions like mixing time, mixing temperatures, conditioning time, and WMA type. A comparison between fine and coarse extracted samples immediately showed that the binder from virgin and RAP aggregate is not similar and is not fully blended. Degree of blending proved to be sensitive to WMA modification and mixing time while not displaying any significant differences when comparing conditioning time and mixing temperature. Most WMA RAP trials in this study produced degree of blending values ranging from 70% to 90% while HMA RAP trials were 50% to 70%. The study showed that WMA RAP mixtures activate more RAP binder than conventional HMA RAP mixtures and thus field application would not require adverse plant modification. Polymer degradation of WMA was also studied to determine whether lower production temperatures could decrease polymer degradation. Gel permeation chromatography was used to measure molecular weight of polymer and binder particles at original, RTFO 133°C, and RTFO 163°C conditions. Evotherm® was the most sensitive binder at increasing conditioning temperatures and experienced the most polymer degradation while Sasobit® showed the least amount of degradation. Proceeding a statistical analysis it was determined that no significant differences occurred when comparing original binders and RTFO 133°C which would indicate a better preservation of the original state of the binder and better long term performance.

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