Effects of pore structure on oxidative aging and related mechanical properties of asphalt concrete

Abstract

Aging in asphalt concrete (AC) is an important issue that has been well studied by researchers for decades. Although some works have been conducted to evaluate the effect of total pore on aging, there is lack of study on how different type of pores or pore structure affects the aging process and related mechanical properties. This study attempted to evaluate the effects of pore structure on oxidative aging and related mechanical properties of AC. Slab samples were prepared in the laboratory using a linear kneading compactor. Air voids of the samples range from 7% to 20% to cover dense graded to highly open graded pavements. Samples were kept inside the laboratory for three years to age by action of air only. Pore structure was evaluated using tracer test. Aging was quantified using Fourier Transform Infrared Spectroscopy (FTIR). Mechanical properties were determined by binder fatigue test using a Dynamic Shear Rheometer (DSR) and by nanoindentation. It was observed that aging increases with the increase of total pore, effective pore, or permeable pore. Moduli from both nanoindentation and DSR increase with the increase of all type of pores. Fatigue life decreases linearly with the increase of all type of pores. It was also observed that the use of permeable or effective pores doesn’t improve the accuracy of the pore versus aging study.