二次热压实作用对乳化沥青冷再生混合料性能的影响

Influence of Secondary Thermal Compaction on Property of Emulsified Asphalt Cold Recycled Mixture

为了量化分析现场二次热压实作用对乳化沥青冷再生混合料性能的影响,基于常规力学性能试验、Overlay Tester反射裂缝试验、低应变水平下的四点弯曲疲劳试验,对比分析了现场铺筑上覆热拌沥青混合料前后乳化沥青冷再生芯样与室内马歇尔试样的力学性能差异。量化分析了现场二次热压实作用对乳化沥青冷再生混合料力学性能及耐久性能的增强效果,并基于工业CT无损检测技术,分析了现场二次热压实作用对乳化沥青冷再生混合料微细观空隙结构的影响规律。结果表明:现行规范推荐的马歇尔二次击实方法并不能很好地模拟现场实际压实状况,现场二次热压实对乳化沥青冷再生混合料力学性能、抗反射裂缝性能和抗疲劳耐久性能均有明显增强作用;现场压实乳化沥青冷再生混合料内部的大空隙数量和等效空隙直径均小于马歇尔击实成型,二次热压实作用对乳化沥青冷再生混合料空隙级配影响显著;现场二次压实作用对乳化沥青冷再生混合料力学性能和疲劳性能的改善机理在于二次压实作用增强了乳化沥青冷再生混合料密实度,降低了微细观空隙直径,改善了微细观空隙级配。

To quantify the influence of field secondary thermal compaction on the performance of emulsified asphalt cold recycled mixture,based on routine mechanical property test,Overlay Tester reflection crack test,and four-point bending fatigue test under low strain level,the mechanical properties of emulsified asphalt cold recycled core sample and indoor Marshall sample before and after laying hot mix asphalt on site are compared and analyzed.The enhancement influence of field secondary thermal compaction on mechanical properties and durability of emulsified asphalt cold recycled core sample is quantitatively analyzed.The influence of field secondary thermal compaction on microscopic void structure of emulsified asphalt cold recycled mixture is analyzed.The result indicates that the Marshall secondary compaction method recommended by the current regulations cannot simulate the actual field compaction condition well,and the field secondary thermal compaction can significantly enhance the mechanical properties,anti-reflective crack properties,and anti-fatigue durability of cold recycled asphalt mixture.The number of large voids and the diameter of equivalent voids in cold recycled mixture of emulsified asphalt are smaller than those with Marshall molding method.The influence of secondary thermal compaction on voids gradation of cold recycled mixture is significant.The improvement mechanism of field secondary compaction on mechanical properties and fatigue properties of emulsified asphalt cold recycled mixture is that the density of emulsified asphalt cold recycled mixture is enhanced by using the secondary compaction.The micro-void diameter is reduced,and the microscopic void gradation is improved.