In the quest for sustainable and durable road construction materials, researchers have made a significant stride by unraveling the intricate relationship between bonding characteristics and the performance of rubberized reclaimed asphalt pavement (RAP) mixtures. This breakthrough, led by Ling Xu from the College of Civil Engineering at Fuzhou University in China, could revolutionize how the construction industry approaches the use of recycled materials, offering both environmental and economic benefits.
The study, published in the journal *Infrastructures* (translated to English as “Infrastructures”), focuses on the adhesion and cohesion properties of asphalt mixtures that incorporate reclaimed asphalt pavement (RAP) and crumb rubber (CR) derived from waste tires. These materials are increasingly popular in road construction due to their sustainability and cost-effectiveness. However, their performance, particularly in terms of rutting resistance and moisture susceptibility, has not been fully understood until now.
Ling Xu and her team investigated how the bonding characteristics of these mixtures affect their overall performance. They evaluated two RAP sources with different aging levels and two CR particle sizes (250 μm and 380 μm). The results were compelling. Binder bond strength (BBS) tests revealed that smaller CR particles and more highly aged RAP led to increased pull-off strength, indicating better bonding. This was corroborated by rotational viscosity and penetration tests, which showed a corresponding increase in binder stiffness.
One of the most significant findings was the improved rutting resistance of the mixtures, as demonstrated by Hamburg wheel track (HWT) tests. “The high-temperature viscoplastic deformation analysis showed that our mixtures exhibited superior resistance to rutting, which is a critical factor in the longevity of road surfaces,” explained Ling Xu. This is a game-changer for the energy sector, as it means that roads can be built to last longer with fewer repairs, reducing maintenance costs and the environmental impact of frequent roadworks.
Moreover, the study found that boiling tests, supported by image analysis, revealed reductions in stripping ratios, indicating enhanced moisture resistance. This is particularly important in regions with high rainfall or fluctuating weather conditions, where moisture susceptibility can significantly shorten the lifespan of road surfaces.
The statistical analysis confirmed that the content of crumb rubber had a significant effect on bonding characteristics, while the aging of RAP and the size of CR particles jointly influenced rutting performance. Mixtures incorporating 10% CR and 25% RAP achieved the best balance between adhesion, cohesion, and durability.
This research provides a quantitative understanding of how interfacial bonding governs the mechanical performance and moisture resistance of rubberized RAP mixtures. It offers a roadmap for future developments in the field, guiding engineers and construction professionals in optimizing the use of recycled materials. As Ling Xu noted, “Our findings not only enhance the performance of road surfaces but also contribute to the circular economy by maximizing the use of waste materials.”
The implications for the energy sector are substantial. By improving the durability and performance of road surfaces, this research can lead to more efficient use of resources, reduced maintenance costs, and a lower environmental footprint. It’s a win-win scenario that aligns with the growing demand for sustainable and cost-effective construction solutions. As the construction industry continues to evolve, this study serves as a beacon, illuminating the path towards a more sustainable and resilient future.