新旧沥青融合程度对热再生沥青混合料性能影响

沥青混合料热再生过程中新旧沥青融合程度对其混合料的性能影响显著,目前我国热再生沥青混合料进行配合比设计时并未考虑新旧沥青的融合问题。为探究新旧沥青融合程度对热再生沥青混合料工作性能及配合比设计的影响,在质量分数为20%、30%、40%、50%废旧沥青路面回收材料(RAP)掺量下,对常规拌和方式及模拟新旧沥青100%融合拌和方式制备的热再生沥青混合料的高温抗车辙性能、低温抗裂性能、水稳定性以及抗反射开裂性能展开系统地对比研究,在建立两种拌制方式下路用性能差异与RAP掺量之间关系的基础上,确定了需要考虑融合程度的界限RAP掺量。结果表明:随着RAP掺量增大,混合料的高温性能增强,低温性能、水稳定性以及抗反射开裂性能降低;与常规拌和方式相比,新旧沥青100%融合条件下拌制混合料的低温性能、水稳定性以及抗反射开裂性能更优,高温性能较差;两种混合料之间高温性能差异、低温性能差异以及水稳定性差异随RAP掺量的增加逐渐增大,抗反射开裂性能差异无显著变化;以性能差异平均增长率所对应的RAP掺量为界限掺量,提出当RAP掺量大于30%时,热再生混合料设计中应考虑新旧沥青融合程度的影响。

Influence of Blending Degree Between Aged and Virgin Asphalt on Performance of Hot Recycled Asphalt Mixture

The blending degree between aged and virgin asphalt has a significant influence on performance of asphalt mixture in hot recycling procedure. At present, the blending degree is not considered in the mix design of hot recycled asphalt mixture in China. In order to explore the influence of the blending degree on technical performance and composition design of hot recycled asphalt mixtures, the high temperature performance, low temperature performance, water stability and anti-reflection cracking performance of the mixture prepared by conventional mixing method and artificially simulated 100% blending with mass fraction of 20%, 30%, 40%, 50% recycled materials for waste asphalt pavement (RAP) were studied. On the basis of establishing the relationship between road performance difference and RAP content under two mixing methods, the boundary RAP content which needs to consider the blending degree was determined. The results show that with the increase of RAP content, the high temperature performance of the mixture is enhanced, while the low temperature performance, water stability and anti-reflection cracking performance are reduced. Compared with the conventional mixing, the low temperature performance, water stability and anti-reflection cracking performance of the mixture mixed with 100% blending between aged and virgin asphalt are better, but the high temperature performance is poor. The difference of high temperature performance, low temperature performance and water stability increases gradually with the increase of RAP content, while the difference of anti-reflection cracking performance do not change significantly. Taking the content corresponding to the average growth rate of performance difference as the boundary content, it is recommended that when the RAP content is more than 30%, the influence of the blending degree between aged and virgin asphalt should be considered in the design of hot recycled asphalt mixture.