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e 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. is 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. is 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.

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The compaction of asphalt mixtures has a significant influence on their performance. Insufficient compaction leads to several distresses, such as premature permanent deformation, excessive aging, and moisture damage, even if all desirable mixture design characteristics are met. Currently, no acceptable method relates asphalt pavement density to the compaction pattern. The compaction pattern required to achieve the desired density is established on the basis of experience and trial and error, a process that is time-consuming and expensive. This study involved comprehensive experimental evaluation of several test sections that were constructed with different asphalt mixtures by various compaction methods. Results of these experiments were used to determine the effects of compaction temperature, compaction method, mixture design, and base type on the compactability of asphalt mixtures. In addition, the paper presents a systematic method to determine the compaction pattern required to achieve the desired density of asphalt pavements. This method lends itself to integration in an automated system that can be used by roller operators to estimate density during construction.

Pavement friction is one of the primary factors that affect highway safety. Pavements with adequate surface friction reduce the number of wet skidding crashes. The objective of this study was to develop a predictive model for friction loss on pavement surfaces. The model incorporates parameters that describe aggregate shape characteristics, aggregate resistance to abrasion and polishing, aggregate gradation, and polishing cycles. This model was developed on the basis of the results of a comprehensive experimental program. Square-shaped slabs of different asphalt mixtures were prepared in the laboratory by using a linear kneading compactor and polished with a wheel-polishing device. The frictional characteristics of the surface of the test slabs were measured after different intervals of polishing, and statistical analysis was performed to relate friction to mixture and aggregate characteristics.