Investigating the Blending Mechanism and Strength Development of 100% Hot In-place Recycled Asphalt Mixtures

The current tendency in the asphalt paving industry is to increase the utilization of recycled asphalt pavement (RAP). Hot in-place recycling (HIR) is a promising approach to consume 100% RAP from the existing pavement for pavement surface rehabilitation in the field. However, some concerns remained regarding the utilization of HIR techniques in pavement rehabilitation: 1. Whether it is cost-effective to apply the in-place recycling techniques to pavement rehabilitation compared to the conventional HMA surface milling & filling? 2. How to improve the performance of the asphalt mixtures with HIR technique? 3. How much RAP binder can be available for coating the aggregates during HIR? 4. What are the bonding mechanisms, the influence of effective asphalt content and properties on the performances of the HIR mix? 5. What are the contributions of the immobilized RAP binder?

To better understand the pavement performance and recycling efficiency during HIR procedure, the overall objective of the proposed doctoral study is to investigate the blending mechanism and strength development of asphalt mixtures during HIR technique. The research scopes are to (1) investigate the blending mechanism of HIR mixes relating to binder mobilization and mixture mechanical properties; (2) develop an approach to quantify the recycling efficiency of HIR mixes; (3) explore the mechanism of bonding, effects of the degree of blending, and properties of effective binder in HIR mixes; (4) investigate the effects of immobilized RAP binder on asphalt-aggregate interactions and the performance of 100% recycled asphalt mixtures. The results of this study provide a better understanding of the significance of mobilized and immobilized RAP binder on the recycling efficiency of 100% recycled asphalt mixtures.