Date of Award

January 2015

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Civil Engineering

First Advisor

Nabil Suleiman

Abstract

With the concept of sustainable pavement materials and construction gaining acceptance in recent years, Warm Mix Asphalt (WMA) technology has been seen as a valid tool in realizing such sustainability. The low energy requirements and low emissions of WMA production and placement compared to Hot Mix Asphalts (HMA), synthesizes the sustainability appeal. As WMA pavements afford compaction at temperatures several dozen degrees lower than HMA, the rate of cooling drops dramatically allowing paving to continue into colder weather. North Dakota Department of Transportation (NDDOT) has used WMA technology in pavement construction in recent years hoping to extend the relatively short construction season.

Due to the lower mixing and compaction temperatures, the binders in warm mixes tend to exhibit less aging (stiffening) than the binders in hot mixes. In a previous study by a graduate student in civil engineering three years ago, the rut resistance of newly constructed WMA overlay near Valley City, WMA was found to be less rut resistant than their HMA specimen counterparts. For this study, field samples from the Valley City project were collected after being in service (aged) for three years. The research aims at comparing aged WMA rutting resistance to that when the specimens were newly constructed. The Asphalt Pavement Analyzer (APA) is used to compare the rutting resistances of WMA and the control HMA. Addressing the issue of binder aging and its effects on the overall rut performance of pavements gives further insight into the utility of WMA overlays in North Dakota.

The results show that there was a significant improvement in rutting resistance for aged WMA over un-aged WMA mixes. Even-though, the aged WMA specimens were less rut resistant than the aged HMA control sections, the rut resistance of WMA mixes under wet conditions show promising potential for durable WMA mixes.

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