界面水对沥青复合小梁疲劳性能的影响

Influence of Interfacial Water on Fatigue Performance of Composite Asphalt Beam

为探讨界面水对沥青铺面使用性能产生的影响,拟采用含有层间界面的复合沥青小梁为试验对象,并以四点弯曲小梁试验为主,直接剪切试验为辅的试验方法,分别以层间洒水量和试件浸水天数为影响因素,模拟施工和使用中铺面渗水情况,测定其在不同试验条件下,复合小梁的抗剪强度及疲劳性能。通过复合小梁纵剖面激光扫描,分析了不同界面水来源状态下的复合小梁水损害机理。试验结果表明:(1)浸水天数对复合小梁的层间抗剪强度影响要大于层间洒水量对其的影响;(2)在相同试验条件下,随着层间洒水量或浸水天数的增加,复合小梁的疲劳寿命对数衰减率呈现增加趋势,但增加趋势有所不同。其中,浸泡达到一定天数后其增加趋势明显变缓;(3)复合小梁试件弯曲劲度模量的损失随层间洒水量的增加呈非线性增加,但损失量不超过10%;而随试件浸水天数的增加,其损失量也逐渐增大,最大达到31%,在浸水5 d后,其损失量趋于稳定;(4)复合小梁纵剖面激光扫描显示,层间洒水使复合小梁在层间界面出现细小的空隙,而试件浸水后在界面上层混合料内部出现大面积的集料剥离,故浸水导致复合小梁性能下降更严重。

In order to investigate the influence of interface water on the performance of asphalt pavement, the composite asphalt beam which has interlayer is used to carry out the four-point bending beam test and the direct shear test.The water seepage in pavement during road construction and service is simulated considering the influence of interlayer water sprinkle and the number of days of water immersion on the specimen, and the shear strength and fatigue performance of the composite asphalt beam under different conditions are measured. By laser scanning on the longitudinal profile of the composite beam, the water damage mechanism of composite beam under different interface water sources is analyzed. The test result shows that(1) the influence of immersion days on the interlayer shear strength of composite beam is greater than that of interlayer water sprinkle;(2) under the same test condition, the logarithmic decay rate of fatigue life increased with the rise of the interlayer water sprinkle or the number of days of water immersion, however, the increase trend is different, where the increase trend after immersion for a certain number of days obviously slowed down;(3) with the increase of the interlayer water sprinkle, the bending stiffness modulus loss of the composite beam increased nonlinearly, and the loss is less than 10%;(4) with the increase of water immersion days, the bending stiffness modulus loss increased gradually, reaching 31%, but it became stable after 5 days;(4) the laser scanning shows that the interlayer sprinkling makes the composite beam appeared small gap in the interface, and the specimen appeared a large area of peeled aggregate inside the upper interface of the mixture after specimen soaked, therefore, the damage of the composite beam caused by immersion is more serious.