Date of Award

January 2016

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Civil Engineering

First Advisor

Daba Gedafa

Abstract

In this study, the change in rheological properties of nanoclay modified asphalt binders was determined in the laboratory. The four performance grade asphalt binders used in this study, PG 58-34, PG 58-28, PG 64-34, and PG 64-28, were modified using Cloisite 20 nanoclay at 1 %, 3%, and 5 % by weight of the asphalt binder. The Dynamic Shear Rheometer (DSR) was used to measure the rheological properties of the unmodified and modified asphalt binders and determine the change in performance properties. The non-modified and modified asphalt binders were also used to create nanoclay modified asphalt specimens using the Superpave Gyratory Compactor (SGC). The rutting resistance of nanoclay modified hot mix asphalt (HMA) specimens were determined using an Asphalt Pavement Analyzer (APA).

The results of the DSR testing show that the nanoclay increases the stiffness of the asphalt. The failure temperature of the asphalt binder generally increased with an increase in nanoclay content. An average of 5.57°C, 1.39°C, 1.81°C, and 2.89°C increase in failure temperature for PG 58-28, PG 58-34, PG 64-28, and PG 64-34 was observed between the 3% and 5% nanoclay mixes. This was confirmed with the low-temperature rheological testing of the asphalt binder. The low-temperature results were interpreted using storage modulus master curves. These master curves showed that the storage modulus increased with an increase in nanoclay. The HMA specimens were tested for rutting resistance using the APA. The results showed that the rutting resistance of HMA specimens based on nanoclay modified asphalt binder was improved as nanoclay content increased. Furthermore there was a better linear correlation with the increase in nanoclay content than there was with the number of gyratory compactor compaction cycles during the preparation of the specimens.

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