考虑残存发泡水影响的泡沫温拌沥青/集料界面粘附性衰减机理研究

Foam warm mix asphalt (FWMA) is a green pavement material for energy conservation and emission reduction. However, the lower mixing temperature and shorter mixing time make it difficult to remove all foaming water, resulting in water residual and endangering the water stability of FWMA. This project intends to study the deterioration mechanism of asphalt/aggregate interface adhesion characteristics under the influence of residual foaming water, because the asphalt/aggregate interface is closely related to water stability by combining micro-and macro-methods. On the basis of obtaining the water migration behavior and residual state after foaming, the damage behavior and action principle of residual foaming water on the adhesion of asphalt were proved from the micro-scale, With the help of atomic force microscopy (AFM). Using the spalling test, drawing test and surface energy calculation of asphalt/aggregate under macroscopic scale, the weakening rule of residual foaming water on macroscopical adhesion of asphalt/aggregate is grasped. The influence of micro-interface properties of asphalt on its macro-adhesion under the action of residual water was investigated, and the internal relationship and interaction mechanism of macro-and micro-adhesion characteristics of asphalt/aggregate were established. From the point of view of asphalt micro-adhesion damage, the degradation mechanism of asphalt/aggregate interface adhesion under the influence of residual water is revealed. It is expected that the results of the project will provide a theoretical basis for objective evaluation of water stability of FWMA and have important guiding significance and reference value for effective control of water damage of FWMA.

泡沫温拌沥青混合料（FWMA）是一种节能减排的绿色筑路材料。但较低的拌合温度和较短的拌合时间，导致引入的发泡水分难以全部排除而出现残存，危及FWMA的水稳定性。本项目拟运用微观和宏观相结合的方法，从与水稳定性密切相关的沥青/集料界面入手，开展残存发泡水影响下沥青/集料界面粘附特性衰减机理研究。在掌握发泡后水分迁移行为和残存状态的基础上，借助原子力显微镜技术，从微观尺度探明残存发泡水对沥青粘附性的损伤行为和作用原理；利用沥青/集料剥落、拉拔试验及表面能测算，从宏观尺度掌握残存发泡水对沥青/集料粘附性能的削弱规律；考察残存水作用下，沥青微观界面属性变化对其宏观粘附性的影响，建立沥青/集料宏微观粘附特性的内在联系和相互作用机制；从沥青微观粘附损伤角度，揭示残存水影响下沥青/集料界面粘附的衰减机理。项目研究为客观评价FWMA水稳定性提供理论基础，对有效控制FWMA水损害具有重要指导意义和参考价值。

随着“绿色交通”和“低碳减排”理念逐渐成为社会关注的焦点和未来发展的趋势，泡沫温拌沥青技术逐渐得到应用和关注。尽管部分应用认为泡沫温拌沥青路面与常规热拌沥青路面的短期性能相差不大，但目前研究人员普遍对泡沫温拌沥青混合料（FWMA）水稳定性表示担忧。残存发泡影响下的沥青路面水损害机制与以往研究不同，现有成果无法解释残存发泡水影响下的水损害机理，基础理论的缺失成为制约泡沫温拌技术推广应用的瓶颈。本课题的研究旨在运用微观和宏观相结合的方法，从与水稳定性密切相关的沥青/集料界面入手，开展残存发泡水影响下沥青/集料界面粘附特性衰减机理研究。取得成果如下：（1）借助光学显微镜和环境扫描电镜等微观分析方法，探明了发泡水分在泡沫温拌沥青混合料生产、施工及运营过程的总量逐渐减小，但仍有0.15%左右的水分残存，且其水分主要留存于沥青内部；（2）提出了基于固态干冰急冻技术捕捉不同状态泡沫温拌沥青的方法，采用原子力显微镜（AFM）得到了泡沫温拌沥青二维和三维角度下的形貌图、相图、粗糙度、高程等信息，获得不同发泡用水量下沥青的界面纳观结构特性；（3）研究了不同沥青类型和不同残存水量对沥青微观界面属性的影响，发现随着残存水量的增加，沥青表面粗糙程度明显增大，“蜂形结构”不断的减少，泡沫温拌沥青的微观界面属性与其粘附行为密切相关；（4）开展了泡沫温拌沥青与集料的自由表面能和拉拔试验，建立了泡沫温拌沥青微观结构形态分布特征与粘聚能、粘附功（有水、无水条件）、拉拔强度的定量关系，掌握了泡沫温拌沥青/集料宏微观粘附特性的内在联系，揭示了残存水对泡沫温拌沥青粘附性能的损伤行为和作用机理。项目成果为解决泡沫温拌沥青/集料体系界面粘附性研究提供了新思路，为客观评价FWMA水稳定性提供理论基础，为有效控制FWMA水损害提供了指导意义和参考价值。