Civil Engineering ETDs

Publication Date

2-14-2014

Abstract

Depending on the region, in a single year, the pavement undergoes many cycles of freezing and thawing. Freeze-thaw, as well as traffic loading, are important parameters in the study of damage in asphalt pavement. In areas of wide ranging temperatures, pavements are susceptible due to thermal cracking. This study investigates the effect of freeze-thaw on fatigue life and material characteristics of Hot Mix Asphalt (HMA) and binder. Since, temperature is variable throughout the year, a constant temperature should not be assumed when finding the fatigue life and material characteristics of HMA. To evaluate the damage, flexure test is conducted to determine the effect of freeze-thaw on the modulus and the fatigue life. In concurrence with the flexure test, indirect tensile (IDT) strength test is performed on the same mix with similar freeze-thaw conditioning to determine the reduction in the strength of HMA. Furthermore, Bending Beam Rheometer (BBR) test is performed on the binder that is used for the HMA. Similarly, the binder is also subjected to freeze-thaw conditioning to determine the stiffness with respect to increasing freeze-thaw. The findings from this study show that freeze-thaw has a negative effect on HMA. The freeze-thaw conditioning decreases the stiffness by 5.3%, 5.9%, 9.0%, 16.8% and the fatigue life of the pavement by 35.8%, 36.1%, 53.6%, 37.4% for 5, 10, 15, and 20 freeze-thaw cycles, respectively. As the failure criteria for the four-point bending test is 50% of its initial stiffness, the reduction in initial stiffness due to freeze-thaw negatively affects the life of the pavement. The findings from the IDT strength test show a decrease in indirect tensile strength of AC by 0.8%, 2.0%, 2.2%, and 2.6% for 5, 10, 15, and 20 cycles of freeze-thaw. Although, a decrease in trend in seen, performing ANOVA analysis, the decrease in mean is statistically insignificant. The findings from the BBR test show that freeze-thaw causes damage to the binder, which can be seen in the reduction of stiffness with increasing freeze-thaw. The reduction in stiffness for 5, 10, 15, and 20 freeze-thaw cycles are 7.1%, 31.5%, 38.9%, and 41.1%, respectively.

Keywords

freeze-thaw, beam fatigue, IDT, BBR

Document Type

Thesis

Language

English

Degree Name

Civil Engineering

Level of Degree

Masters

Department Name

Civil Engineering

First Committee Member (Chair)

Maji, Arup

Second Committee Member

Taha, Mahmoud

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