基于RCA指标与响应曲面法的再生沥青混合料设计及性能研究

Design and Performance Study of Recycled Asphalt Mixture Based on RCA Indicator and Response Surface Methodology

摘要:

为实现无废公路建设目标并提升再生沥青混合料（RAP，reclaimed asphalt pavement）的利用率，针对传统掺量指标未能区分RAP粗、细组分性能影响差异的问题，提出了RAP粗骨料替代率（R_CA）指标。研究以R_CA为核心变量，采用响应曲面法优化后AC-20型配比的沥青混合料，系统测试其高温、低温及水稳定性能，并进行了相应的工程示范应用。结果表明：随着R_CA的增加，混合料高温稳定性显著提升，但低温抗裂性及水稳定性下降，当R_CA超过50%时，混合料的最大弯拉应变接近《公路沥青路面再生技术规范》（JTG/T 5521—2019）限值，达到70%时，混合料的浸水残留稳定度和冻融劈裂强度比已不满足规范要求；R_CA为30%的热再生混合料施工性能良好。相较于传统RAP掺量指标，R_CA指标能更精准地表征RAP对混合料路用性能的影响机制，可为后续提升再生混合料设计水平提供参考价值。

Abstract:

To achieve the goal of "No-Waste Highway" construction and improve the utilization rate of Reclaimed Asphalt Pavement (RAP), this study proposes the RAP Coarse aggregate replacement ratio (R_CA) indicator, addressing the limitation of traditional RAP content metrics in differentiating the performance impacts of coarse and fine RAP components. Using R_CA as the core variable, the mix proportion of AC-20 mixture was optimized via response surface methodology. Its high-temperature, low-temperature, and moisture stability performance were systematically tested, followed by a corresponding engineering demonstration. The results indicate that: (1) As R_CA increases, the high-temperature stability of the mixture improves significantly, while its low-temperature crack resistance and moisture stability decline. When R_CA exceeds 50%, the maximum flexural tensile strain approaches the specification limit, and at 70%R_CA, the retained Marshall stability and freeze-thaw splitting strength ratio fail to meet the specification requirements; (2) The engineering application confirms that the hot recycled mixture with an R_CA of 30% exhibits good construction performance. Compared to the traditional RAP content indicator, the R_CA indicator can more precisely characterize the influence mechanism of RAP on the pavement performance of the mixture, providing valuable reference for enhancing the design level of recycled mixtures in the future.