Li Zhenxia, Guo Tengteng, Chen Yuanzhao, Zhang Tong, Tang Deqing, Hao Menghui, Zhao Xu, Liu Jinyuan
School of Civil Engineering and Communication, North China University of Water Resources and Electric Power, Zhengzhou 450045, China.
Henan Province Engineering Technology Research Center of Environment Friendly and High-Performance Pavement Materials, Zhengzhou 450045, China.
Polymers (Basel). 2023 Apr 20;15(8):1958. doi: 10.3390/polym15081958.
To give full play to the advantages of polyurethane as a binder, such as mixing at room temperature, short curing time, and high curing strength, polyurethane was used as the binder of a waste asphalt mixture, and the pavement performance of PCRM (Polyurethane Cold-Recycled Mixture) was analyzed. Firstly, the adhesion performance of polyurethane binder with new and old aggregates was evaluated using the adhesion test. Then, the mix proportion was designed according to the material characteristics, and the reasonable molding process, maintenance conditions, design indexes, and the optimal binder ratio were proposed. Secondly, the high-temperature stability, low-temperature crack resistance, water stability, and compressive resilient modulus of the mixture were evaluated through laboratory tests. Finally, the pore structure and microscopic morphology of polyurethane cold-recycled mixture were analyzed by industrial CT (Computerized Tomography) scanning, and the failure mechanism of polyurethane cold-recycled mixture was revealed. The test results show that the adhesion between polyurethane and RAP (Reclaimed Asphalt Pavement) is good, and the splitting strength of the mixture increases greatly when the ratio of glue to stone reaches 9%. Polyurethane binder has low sensitivity to temperature and poor water stability. With the increase of RAP content, the high-temperature stability, low-temperature crack resistance, and compressive resilient modulus of PCRM showed a decreasing trend. When the RAP content was less than 40%, the freeze-thaw splitting strength ratio of the mixture was improved. After the incorporation of RAP, the interface was more complex and there were many micron-scale holes, cracks, and other defects; after high-temperature immersion, the polyurethane binder appeared to show a certain degree of peeling at the holes of the RAP surface. After freeze-thaw, the polyurethane binder on the surface of the mixture produced many cracks. The study of polyurethane cold-recycled mixture is of great significance to realize green construction.
为充分发挥聚氨酯作为粘结剂的优势，如室温混合、固化时间短、固化强度高，将聚氨酯用作废旧沥青混合料的粘结剂，并对聚氨酯冷再生混合料（PCRM）的路用性能进行了分析。首先，采用粘结试验评价了聚氨酯粘结剂与新、旧集料的粘结性能。然后，根据材料特性设计了配合比，提出了合理的成型工艺、养护条件、设计指标及最佳粘结剂用量。其次，通过室内试验对混合料的高温稳定性、低温抗裂性、水稳定性和抗压回弹模量进行了评价。最后，通过工业CT（计算机断层扫描）扫描分析了聚氨酯冷再生混合料的孔隙结构和微观形貌，揭示了聚氨酯冷再生混合料的破坏机理。试验结果表明，聚氨酯与RAP（旧沥青路面材料）之间的粘结良好，当胶石比达到9%时，混合料的劈裂强度大幅提高。聚氨酯粘结剂对温度敏感性低，水稳定性差。随着RAP含量的增加，PCRM的高温稳定性、低温抗裂性和抗压回弹模量呈下降趋势。当RAP含量小于40%时，混合料的冻融劈裂强度比有所提高。掺入RAP后，界面更加复杂，存在许多微米级的孔洞、裂缝等缺陷；高温浸水后，聚氨酯粘结剂在RAP表面的孔洞处出现一定程度的剥离。冻融后，混合料表面的聚氨酯粘结剂产生了许多裂缝。对聚氨酯冷再生混合料的研究对实现绿色施工具有重要意义。
