利用表面能理论及拉脱试验分析沥青膜的剥离行为

Investigation on Stripping Behavior of Asphalt Film Using SurfaceEnergy Theory and Pull-off Test

水损害是我国沥青路面早期破坏的主要形式,而混合料中沥青膜的剥离行为是沥青路面发生水损害的第一阶段,但目前对沥青膜的潜在剥离面或薄弱界面位置、剥离行为机制缺乏统一认识。为深入了解沥青膜剥离行为特征,以表面能理论为基础,对沥青-集料界面黏附功、沥青内聚功进行量化表征;结合杨氏接触角试验,对比分析了不同沥青-集料组合在无水、有水条件下黏附功与内聚功的相对关系,从理论上推断沥青膜剥离的潜在界面位置;进一步结合沥青-集料附着力拉脱试验,对沥青膜剥离界面进行合理验证。结果表明:无水条件下,沥青内聚功、沥青-集料界面黏附功均为正值,且内聚功显著小于黏附功,沥青混合料薄弱界面位于沥青本体内部;有水条件下,内聚功与黏附功变为负值,表明在水分作用下沥青混合料中内聚破坏、界面黏附破坏均趋向自发性。附着力拉脱试验验证表明,干燥状态下,同种沥青与不同集料间附着力基本相当,破坏类型判定为沥青内聚损失C,沥青膜剥离面位于沥青本体内部;浸水状态下,破坏类型为界面黏附破坏A以及混合破坏C/A,沥青膜剥离面由沥青本体内部转移至沥青-集料界面处。本工作基于表面能理论及拉脱试验方法,分析了不同条件下沥青混合料剥离现象形成机制,为提高混合料抗水损害性能提供理论与试验基础。

Moisture-induced damage is the main form of early failure of asphalt pavement in China,and stripping behavior of asphalt film is the first stage of moisture-induced damage in asphalt pavement.To further understand the characteristics of asphalt film stripping behavior,the adhesive work of asphalt-aggregate interface and the cohesive work within asphalt were quantitatively characterized using surface energy theory.Surface energy parameters of different asphalts and aggregates were tested by Young contact angle.The adhesive work of asphalt-aggregate combinations and the cohesive work within different asphalts were calculated under the dry condition and presence of water respectively.The relative magnitudes between adhesive work and cohesive work were compared to infer the potential position of stripping interface.A theoretical proof for stripping interface was provided by the pull-off test.The results showed that cohesive work and adhesive work are both positive without water in asphalt-aggregate system.The cohesive work is significantly less than adhesion work,indicating that the weak interface within asphalt mixture is located inside the asphalt body.With the presence of water,cohesive work and adhesive work are negative,indicating that cohesive failure and adhesive failure tended to be spontaneous in asphalt-aggregate system.The pull-off test shows that,the max breakaway forces between the same asphalt and different aggregates are basically the same on dry condition,and the failure type is determined as cohesive loss C,stripping interface is located inside the asphalt body.When immersed in water,the failure types are interfacial adhesive failure A and mixed failure C/A,and stripping interface is transferred from asphalt body to the asphalt-aggregate interface.This study was conducted based on surface energy theory and pull-off test,providing a theoretical and experimental basis for analyzing the formation mechanism of the stripping phenomenon of asphalt mixture with different conditions and improving the water damage resistance of the mixture.