为解决沥青路面热再生技术中RAP掺量受限,提高沥青混合料再生利用效益,对热再生沥青混合料的RAP掺量开展了研究.首先,从试验材料的性能测试着手,严格控制试验材料的质量,对 7 种不同RAP掺量下再生沥青混合料进行详细的配合比设计;然后通过高温车辙试验、浸水马歇尔试验、冻融劈裂试验、小梁低温弯曲试验和间接拉伸疲劳试验,综合测试不同RAP掺量下AC-20 型再生沥青混合料的高温稳定性、水稳定性、低温抗裂性和疲劳耐久性等 4 类路用性能;最后,采用灰色关联度分析方法,确定了RAP掺量与路用性能评价指标之间的关联程度.结果表明:(1)随着RAP掺量的增加,再生沥青混合料的高温性能逐渐提高,水稳、低温和疲劳性能逐渐下降,并且其高温、低温和水稳性能的评价指标均在 30%~40%的RAP掺量范围内加速变化,而疲劳性能的评价指标在 40%~50%RAP掺量范围内加速变化;(2)灰色关联度分析显示RAP掺量与再生沥青混合料的动稳定度联系最为紧密,因此其高温性能对RAP掺量变化最为敏感;(3)根据再生沥青混合料路用性能评价指标与RAP掺量的灰色关联度分析结果,并结合路用性能随RAP掺量增加的变化规律以及沥青路面结构层功能,综合确定本批AC-20 型再生沥青混合料中RAP合理掺量范围为 35%~40%.
In order to solve the limitation of recycled asphalt mixture(RAP)content in asphalt pavement thermal regeneration technology and improve the recycling efficiency of asphalt mixture,the RAP content of hot recycled asphalt mixture is studied.Firstly,starting from the performance test of the test material,the quality of the test material is controlled strictly,and the mix ratio of recycled asphalt mixture with 7 different RAP contents is designed in detail.Then,through a high-temperature rutting test,water immersion Marshall test,freeze-thaw splitting test,low-temperature trabecular bending test and indirect tensile fatigue test,the performance of AC-20 reclaimed asphalt mixture with different content of RAP is evaluated.Finally,the correlation degree between RAP content and road performance evaluation indicator is determined by grey correlation degree analysis.The result shows that(1)With the increase of RAP content,the high-temperature performance of recycled asphalt mixture gradually is improved,and the water stability,low temperature and fatigue performance decrease progressively.In addition,the evaluation indicators of high temperature,low temperature and water stability are all intensified within the range of 30%to 40%RAP content,while the evaluation indicators of fatigue performance increase within the range of 40%to 50%RAP content;(2)Grey correlation analysis shows that RAP content is most closely related to the dynamic stability of recycled asphalt mixture,so its high-temperature performance is most sensitive to the change of RAP content;(3)According to the gray correlation analysis result of the road performance evaluation index of the recycled asphalt mixture and the RAP content,and combined with the change rule of road performance with the increase of RAP content and the function of asphalt pavement structure layer.It is comprehensively determined that the reasonable content of RAP in AC-20 recycled asphalt mixture ranges from 35%to 40%.