Gus Yazdani

Date of Award

January 2018

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Civil Engineering

First Advisor

Daba Gedaga

Abstract

There are some distresses in asphalt pavements such as high temperature permanent deformation (rutting), low-temperature (thermal) cracking, and load-associated fatigue cracking.

Rutting is caused by the accumulated plastic deformation (flow) in the asphalt mixture with repeated application of loads at upper pavement service temperatures. It is predominantly influenced by the aggregate and mix design. Modifiers can stiffen the binder and provide a more elastic material.

Thermal shrinkage cracking results from either a single thermal cycle where the temperature reaches a critical low temperature (Single Event Thermal Cracking) or from thermal cycling above the critical low temperature (Thermal Fatigue).

In this project, elastic polymer (SBS- styrene–butadiene–styrene) and nano TiO2 (Titanium dioxide) were used to modify the virgin PG 58-28 binders. TiO2 nanoparticles were used because they can accelerate the process of trapping and degrading organic and inorganic particles from the air while removing harmful air pollutants, such as NOx, sulfur oxides (SOx), and VOCs in the presence of UV light (sunlight).

Rolling Thin Film Oven (RTFO) and Pressure Aging Vessel (PAV) were used to simulate short-term and long-term aging of the binder, respectively. Dynamic shear rheometer (DSR) was used to determine rheological properties of unaged, short-term and long-term aged binders. Optimum TiO2 content in 12%SBS was determined based on binder test results. Hot mix asphalt (HMA) was designed with virgin binder (control) and binder modified with SBS and TiO2. Superpave gyratory compactor was used to compact mix specimens.

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Asphalt Pavement Analyzer (APA), Disk-shaped compact tension (DCT), and semi-circular bending (SCB) was used to determine rutting, low-temperature cracking, and fatigue cracking resistance, respectively. Based on the results, 1wt.% TiO2+12% SBS modified PG 58-28 binder and corresponding mix performed the best.

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