Bishal Karki

Date of Award

January 2017

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Civil Engineering

First Advisor

Daba Gedafa

Abstract

Nanotechnology has been increasingly used in asphalt modification for its remarkable effect in improving the binder and mix performance. Rheological properties of binder play major roles in rutting, fatigue cracking and low-temperature cracking resistance of Hot Mix Asphalt (HMA) pavement. This study was conducted to investigate the effect of Nanomaterials (NMs) on the rheological characteristics of asphalt binders and rutting and cracking resistance of HMA mixes. NMs, Nanoclay and Nanoalumina, were mixed separately into Performance Grade (PG) 58-28 and 64-28 asphalt binder at control (0% NM), 1, 5 and 7% by binder weight. Rolling Thin Film Oven (RTFO) and Pressure Aging Vessel (PAV) were used for simulating short-term and long-term aging, respectively. Asphalt specimens (un-aged, RTFO-aged, and PAV-aged from each binder) were tested using Dynamic Shear Rheometer (DSR) to determine and compare the viscoelastic behavior of the asphalt binders at different temperatures. Hot Mix Asphalt Specimens (150mm diameter and 75mm high) were compacted with 71% air voids using Superpave Gyratory Compactor. Asphalt Pavement Analyzer (APA), Semi-Circular Bending (SCB) and Disc-Shaped Compact Tension (DCT) were used to determine the rutting, fatigue cracking and low-temperature cracking resistance of the mixes, respectively. Cracking of mixes was measured in terms of fracture energy. The results showed that Nanomaterials increased the rutting resistance of the mixes by increasing the stiffness of the mixes, but the mixes could be more susceptible to cracking.

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