基于耗散能方法评价硬质沥青混合料抗疲劳性能

Evaluation of Anti fatigue Characteristic of Hard Asphalt Mixture Based on Dissipated Energy Method

关键词:  道路工程  硬质沥青混合料  疲劳性能  四点弯曲疲劳  累计耗散能

Key words:  road engineering  hard asphalt mixture  fatigue characteristic  four point bending fatigue  accumulative dissipated energy

摘要:

为了评价硬质沥青混合料的抗疲劳性能，结合实体工程对硬质沥青混合料SAC25 30#和改性沥青混合料SAC16 SBS进行了室内四点弯曲疲劳对比试验.选用应变和应力2种控制模式,在不同温度下综合测试了2种沥青混合料的抗疲劳性能，采用累计耗散能指标(Wf)分析了其在不同温度下的能量变化趋势，发现不同材料的黏弹特性和刚度差异对其耗散能均有影响，进而引入累计耗散能极限比指标（WfR），并对Wf进行了修正.结果表明：在应力控制模式下,硬质沥青混合料在20，5℃时均具有较好的抗疲劳性能，而在应变控制模式下，由于硬质沥青混合料延展性不足，其在不同温度下的抗疲劳性能均劣于改性沥青混合料；能量法可以统一不同控制模式，20℃时硬质沥青混合料的WfR随疲劳寿命增加的幅度明显小于改性沥青混合料，说明其抗疲劳性能更优，而在5℃时硬质沥青混合料的WfR曲线明显位于改性沥青混合料上方，说明随着温度的降低其疲劳性能有明显减弱趋势.WfR指标可为评价硬质沥青混合料抗疲劳性能提供一定的参考.

Abstract:

In order to evaluate the anti fatigue property of hard asphalt mixture, a series of four point bending fatigue tests were conducted to make a comparison between hard asphalt mixture SAC25 30# and polymer modified asphalt mixture SAC16 SBS. Both strain control mode and stress control mode were considered to make an overall evaluation of anti fatigue properties at different temperatures, and the accumulated dissipated energy Wf was used to analyze the energy variation trends of two mixtures. Besides, the effects of visco elastic parameters and stiffness difference on the dissipated energy were discovered and the ultimate strain and stress were introduced to correct the parameter of accumulated dissipated energy. The result indicates that hard asphalt mixture has a better anti fatigue performance under stress control mode at 20℃ and 5℃, but they are worse than SBS modified asphalt mixtures under strain mode at different temperatures due to their lower ductility. If WfR adopted, WfR of hard asphalt mixtures is lower with the growing fatigue life at 20℃, but WfR curve lies above that of modified asphalt mixture at 5℃, which indicates anti fatigue properties of hard asphalt mixtures have an obvious trend of decrease as temperature goes down. This indicator can be used as a reference to evaluate the fatigue performance of hard asphalt mixture.