泡沫沥青冷再生混合料MMLS3试验轮辙曲线特征及影响机理

对泡沫沥青冷再生混合料进行常温条件下的MMLS3加速加载试验,研究泡沫沥青冷再生混合料的长期使用性能,探讨泡沫沥青冷再生混合料的车辙变深度、变形速率及横断面轮辙曲线特征,给出泡沫沥青冷再生混合料车辙深度随加载次数的变化趋势,并对不同加载次数下轮迹处MMLS3试件进行X-ray无损扫描,分析不同加载次数下泡沫沥青冷再生混合料的空隙率分布特征及粗集料运动规律,揭示泡沫沥青冷再生混合料的疲劳损伤规律。研究结果表明：对于未掺加水泥的泡沫沥青冷再生混合料试件,轮迹处车辙沿横断面分布呈U形;掺加1%~2.5%水泥后,泡沫沥青冷再生混合料试件横断面车辙分布呈W形,可采用车辙深度R_DD=AN^B预估不同加载次数N下的车辙深度发展规律;MMLS3加载试验过程中泡沫沥青冷再生混合料车辙发展规律可分为3个阶段,即压密阶段、蠕变稳定阶段、剪切破坏阶段;重复疲劳荷载作用下轮辙变形主要来源于泡沫沥青砂浆压密变形和集料受荷载作用产生的竖向位移及粗集料自身由不稳定状态转变为"平躺"状态所发生的水平转动位移,粗集料取向角随加载次数增大呈指数函数关系减小。

Characteristics of Fracture Curve of MMLS3 Test and Fatigue Damage Mechanism of Foam Asphalt Cold Recycled Mixture

The long-term performance of foam asphalt cold recycled mixture was studied by MMLS3 accelerated loading under the condition of room temperature. The effects of the asphalt cold recycled mixture on the rutting depth, deformation rate, and cross section are investigated. The characteristics of the rutting curve of the foamed asphalt cold regenerated mixture are analyzed, and X-ray non-destructive scanning of the specimen at the track is carried out. The effects of different times of loading on the asphalt cold recycled mixture are investigated. The porosity distribution and the law of coarse aggregate movement reveal the fatigue damage law of foam asphalt cold regenerated mixture. The results show that the rutting of the trough is not U-shaped along the cross section, and the regenerated mixture of 1%-2.5% cement is used as the cold recycled mixture of foam asphalt. Under different loading times (N), R_DD=AN^B can be used to estimate the rutting development of foam asphalt in the MMLS3 loading test. This law can be divided into the compaction stage, creep stabilization stage, and shear failure stage. The torsional deformation under the repeated fatigue load is mainly due to the vertical displacement and coarse aggregate produced by the compression deformation of the foam asphalt mortar and the load. The horizontal rotation of the coarse aggregate is changed from the unstable state to the "flat" state, and the orientation angle of the coarse aggregate decreases exponentially with the increase in loading time.