State of the Art Study on Aging of Asphalt Mixtures and Use of Antioxidant Additives

TLDR

Hardening of asphalt pavements, first noted in the 1900s, is defined as aging—a chemical-driven change in rheological properties that stiffens and embrittles the material, reducing durability and increasing cracking risk. This review surveys the state of the art on asphalt and mixture aging and evaluates antioxidant additives designed to retard that aging. The authors examine the complex molecular structure of asphalt, its atmospheric degradation, and laboratory aging protocols, with a focus on simulating mixture aging and the mechanisms by which antioxidants mitigate it. The study demonstrates that antioxidant additives effectively retard asphalt aging and improve pavement performance.

Abstract

The detrimental effects of hardening in asphalt pavements were first recognized by pioneering pavement engineers in the 1900s and have been studied extensively during the last 70 years. This hardening process, referred to as asphalt aging, is generally defined as change in the rheological properties of asphalt binders/mixtures due to changes in chemical composition during construction and its service life period. Aging causes the asphalt material to stiffen and embrittle, which affects the durability and leads to a high potential for cracking. This paper presents the state of the art on asphalt and asphalt mixture aging and use of antioxidant additives to retard the aging. A picture of complex molecular structure of asphalt and its changes due to atmospheric condition and various protocols used to simulate aging in laboratory environment are also discussed. Emphasis is given on recent studies on simulation of aging of asphalt mixtures as there has been limited research on mixtures compared to the asphalt binder. Finally, this paper presents the application of antiaging techniques and its mechanism, use of various types of antioxidant additives to retard aging of asphalt and, hence, improve the performance of asphalt pavements.