基于感应加热的沥青混凝土细观裂纹梯度愈合行为研究

Maintaining the asphalt pavement with induction heating activated healing once the meso-cracks occur, can efficiently solve the problem of cracks in asphalt pavement. This project will study the meso crack healing and macro strength recovery behaviors of asphalt concrete activated by induction healing, and establish a theory to describe the gradient healing behavior of asphalt concrete with induction heating. On the one hand, the gradient healing of meso-cracks and the recovery of the bending strength of asphalt concrete after induction heating was respectively investigated by means of Nano Computed Tomography Scan technology and three point bending test. The relationship between meso-crack healing and marco-strength recovery will be explored as well. On the other hand, the finite element method will be employed to simulate the gradient healing process of asphalt concrete with induction healing. The influences of the temperature gradient, thermal conductivity and heat capacity of asphalt concrete, bitumen content and properties, crack size etc. on the gradient healing behaviors of asphalt concrete after induction heating will be studied and a gradient healing model will be developed combined with the actual healing ratios of cracks from CT Scanning. Based on the experimental and numerical studies, this project will finalize a meso-macro united method to characterize the self healing behavior of asphalt concrete, and provide a theoretical basis for the optimization and application of the induction heating technology of asphalt concrete.

在沥青路面刚出现细微裂纹时就利用感应加热自愈合技术加以修复，能够快速有效地解决其裂缝问题。本项目拟从细观裂纹愈合和宏观性能恢复两个层面上研究沥青混凝土的感应加热自愈合行为，建立其裂纹愈合效果随加热深度逐渐变化的梯度愈合理论。分别采用纳米CT扫描技术和三点弯曲实验研究沥青混凝土感应加热的细观裂纹梯度愈合规律和宏观强度恢复规律，揭示细观裂纹愈合与沥青混凝土宏观强度恢复之间的内在关系。通过有限元分析方法模拟沥青混凝土感应加热的愈合过程，揭示温度梯度、裂纹尺寸、沥青混凝土热常数、沥青含量与性能等因素对裂纹周围温度场的影响规律，结合裂纹的实际愈合情况，建立与沥青混凝土感应加热的裂纹梯度愈合过程相吻合的数值模型，构建沥青混凝土感应加热的梯度愈合理论。本项目的实验和模拟研究，将为沥青混凝土的自愈合行为提供一种细观-宏观相结合的分析方法，并为沥青混凝土感应加热自愈合技术的优化和应用提供理论依据。

针对沥青混凝土感应加热速率偏低、愈合行为表征方法不完善、裂纹梯度愈合行为不明确等问题，本项目提出了钢渣钢纤维复合感应加热自愈合沥青混凝土的设计方法，制备了路用性能优良、感应速率高的沥青混凝土；采用纳米CT扫描技术、三点和四点弯曲试验从细观裂纹愈合和沥青混凝土宏观性能恢复两个层面上研究了沥青混凝土的感应加热自愈合行为，建立了细观-宏观相结合沥青混凝土自愈合性能的分析方法，揭示细观裂纹愈合与沥青混凝土宏观强度恢复之间的内在关系；研究了不同感应加热方案下沥青混凝土感应加热的温度梯度分布特性及其导致的梯度愈合行为，绘制了沥青混凝土感应加热的温度梯度分布图谱，为沥青混凝土愈合方式和有效愈合深度的优化提供了先进的测试方法和实用的技术手段，同时发现沥青混凝土感应加热的有效愈合深度为4.3mm，并利用纳米CT扫描技术进行了验证；研究了沥青种类、感应加热温度、湿度、温拌剂、紫外老化、雨雪等因素对沥青及沥青混凝土自愈合性能的影响规律，揭示了湿度、温拌剂和紫外老化对沥青混凝土自愈合性能的作用机制，建立了与沥青混凝土感应加热温度梯度特性相吻合的梯度愈合模型。依托本项目的研究，发表了期刊论文13篇，申请国家发明专利6项，出版学术专著1部，培养硕士研究生6名。本项目的研究成果可为沥青混凝土感应加热自愈合技术的优化和应用提供理论依据。