Abstract
In-plant hot mix recycling technology has been widely used in maintenance and reconstruction due to its good recycling performance. However, the utilization rate of recycled asphalt pavement (RAP) is still only 10–25%, resulting in excessive accumulation and landfilling of RAP materials, which fails to promote the sustainable value of RAP in recycling. Therefore, this paper comprehensively explores the pavement performance of AC-20 ordinary asphalt recycled mixture and AC-13 modified asphalt recycled mixture with different proportions of RAP. The pavement performance test includes the dynamic modulus, rutting, dynamic creep, semicircular bending, and freeze-thaw splitting tests. The results show that, with the increase of RAP content, the mechanical properties and high-temperature properties of the two types of recycled asphalt mixtures are improved, the low temperature properties and moisture susceptibility properties are enhanced first and then weakened, and the best performance is reached when RAP content is 20 and 40%, respectively. According to the entire pavement performance test results, the influence of RAP content on AC-13 recycled modified asphalt mixtures is relatively smaller than that of AC-20 normal recycled asphalt mixtures. The addition of rejuvenator can improve the low-temperature performance and moisture susceptibility of recycled asphalt mixtures to a certain extent, especially for AC-20 ordinary recycled asphalt mixture. Consequently, it is suggested to use AC-13 recycled modified asphalt mixture in the upper layer of road; the RAP content can reach 20%, and rejuvenator can be used to improve its moisture susceptibility and low-temperature performance. AC-20 ordinary recycled asphalt mixture can be used in the middle surface layer, and the RAP content can reach 40%, or using AC-13 recycled modified asphalt mixture, the RAP content can reach 50%.
Highlights
In the United States in 1975, the recycling of asphalt pavement reached 50,000 tons; in 1978, it reached more than 5 million tons, and through the end of the 1980s, the use of recycled asphalt mixes in the United States occupied 50% of the national production of asphalt mixes and furthered related research, such as the development of regenerative agents and the mechanism of asphalt aging.Recycled Asphalt Mixture the requirements of the major U.S states (Thakur, 2010) on the proportion of old material blending are different, the blending rate is roughly 10–50%, and the survey found that most of the asphalt pavement maintained by plant mix hot regeneration technology has a better road performance to meet the requirements of use
The results show that the recycled asphalt pavement (RAP) content ratio can be appropriately increased in AC-13 modified recycled asphalt mix and AC-20 normal recycled asphalt mix to meet the requirements of the road, and the targeted addition of recyclers further improves its low-temperature performance and moisture susceptibility properties
Under low-frequency conditions, the RAP content had a greater effect on the mechanical properties of AC-20 ordinary asphalt recycled mixes, but the mechanical properties of AC-13 modified asphalt recycled mixture has less effect
Summary
In the United States in 1975, the recycling of asphalt pavement reached 50,000 tons; in 1978, it reached more than 5 million tons, and through the end of the 1980s, the use of recycled asphalt mixes in the United States occupied 50% of the national production of asphalt mixes and furthered related research, such as the development of regenerative agents and the mechanism of asphalt aging. Luis (Loria et al, 2011) conducted a study on the road performance of hot mix asphalt pavements with up to 50% RAP in a region of Canada, and the results showed that the water damage resistance and low temperature crack resistance of high-RAP recycled materials could meet the requirements. Whereas increasing the proportion of RAP ensures its road performance meets the actual use requirements, the appropriate amount of regenerant can be introduced to improve the recycled asphalt mixture. The results show that the RAP content ratio can be appropriately increased in AC-13 modified recycled asphalt mix and AC-20 normal recycled asphalt mix to meet the requirements of the road, and the targeted addition of recyclers further improves its low-temperature performance and moisture susceptibility properties. The research results can provide an effective scientific basis and theoretical foundation for the efficient resource utilization of RAP admixture in practical projects
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