基于强化微观结构与可控压实度的沥青路面真空压实技术研究

Insufficient compaction is one of the main influencing factors for low asphalt pavement performance and short service life. The air spring formed by the closed air in asphalt mixture absorbs some energy of the compaction equipment when the asphalt pavement is being compacted, and it is possible to enhance compaction quality and efficiency. However, it is a challenge to achieve controllable and measurable compaction degree. In this project we will reveal the compaction mechanism of asphalt pavement by analyzing the compaction characteristics and propagation rule of compaction energy in the asphalt mixture in the vacuum environment on basis of strengthening microstructure by vacuum compaction. The compaction efficiency can be improved by eliminating air spring effect under vacuum load. The relationship of microstructure and macroscopic asphalt quality will be obtained, and the adhesion rule between asphalt and aggregate under vacuum environment will be revealed by analyzing the influence of micro-pore and interfacial strength between the aggregate and asphalt on the macro-quality of asphalt. Compaction quality can be enhanced by investigating on the compaction method to strengthen the microstructure. The corresponding relationship of vacuum degree, air voids and compaction degree will be researched experimentally, controllable and measurable compaction degree be achieved and the final vacuum compaction machine be designed. In comparison with an ordinary compaction method, a vacuum compaction technology of asphalt will be established. The project exploring of new compaction method belongs to the inter discipline of material and machinery. A vacuum compaction method with independent property rights is highly probable to be obtained.

压实不足是影响沥青路面性能和寿命的主要原因之一，沥青混合料闭口孔隙内封闭气体的"气体弹簧"效应限制了现有压实设备能量的发挥，压实质量和效率仍有提高的空间，而压实度的可测、可控仍是巨大挑战。本项目以真空压实强化微观结构为基础，通过分析真空环境下沥青混合料压实特性和压实能量传播规律，揭示沥青路面真空压实机理；利用真空加载，消除封闭气体的"气体弹簧"效应，提高压实效率；通过分析微观孔隙、沥青与集料界面强度对宏观质量的影响，揭示真空环境下沥青与集料粘附规律，获取微观结构与宏观沥青混合料质量的关系，探讨强化微观结构的压实方法，提升压实质量；依托试验研究，探索真空度、空隙率和压实度三者间对应关系，实现压实度的可测、可控，最终设计出真空压实样机，通过与普通压实的对比，完成沥青路面真空压实工艺。本项目属材料与机械两个学科的交叉，是新压实技术的探索，有望形成具有自主知识产权的沥青路面真空压实技术。

国内外研究表明压实质量不足是影响沥青路面性能和寿命的主要原因之一。沥青混合料是典型的固、液、气三相体系，压实的基本要求是排出气体，固相和液相发生相对位移、重排和嵌挤。普通方法压实时，沥青混合料闭口孔隙内的封闭气体产生“气体弹簧”效应，不但浪费压实能量，而且降低了压实效率，且很难实现压实度的控制和在线检测。为了克服现有压实方法的不足、强化压实过程，本项目提出了将气体由“被动挤出”变为“主动溢出”的一种新的真空压实技术，实现了压实过程的强化。. 主要研究内容包括：分析了真空环境下沥青混合料压实特性，揭示了沥青路面真空压实的机理；利用台架试验装置和试验样机实现了沥青路面压实过程的真空加载，通过消除封闭气体的“气体弹簧”效应，提高了压实效率和质量；通过真空压实与普通压实方法的试验对比，形成了新的沥青路面真空压实技术。结果表明：与其他常用压实方法相比，真空压实获得的沥青路面的空隙率更小，内部孔隙偏小，沥青与骨料界面结合更紧密，微观结构得到强化，这利于提高沥青路面性能和寿命。研究成果获河北省科技进步三等奖一项，发表SCI和EI检索论文各4篇，授权发明专利2项、实用新型专利6项。. 本项目开展的沥青路面真空压实技术使不易压实的三相体系沥青混合料变为较易压实的两相体系材料，不但为沥青路面的压实提供了新的途径和思路，而且首次提出了二相体系路面材料的压实机理，具有良好的科学意义。