Liu Liping, Liu Lingxiao, Yu Ying
The Key Laboratory of Road and Traffic Engineering, Ministry of Education, Tongji University, Shanghai 201804, China.
Polymers (Basel). 2023 Jun 23;15(13):2798. doi: 10.3390/polym15132798.
The application of warm-mixing technology brings considerable economical and environment benefits by decreasing the mixing temperature during warm asphalt mixture (WMA) production. However, the possible water residue also generates concerns for moisture susceptibility. For deep investigation on the influencing factors and mechanisms of the moisture susceptibility of WMA, surface free energy (SFE) tests and laboratory tests are applied in this research. A novel indicator based on SFE, namely, effective adhesion work, is proposed to assess the asphalt-aggregate adhesion with different moisture contents. Then, given the mixing procedure of the dry-mixing method, an advanced three-phase model as a form of asphalt-aggregate-warm mixing additive is introduced, improving the conventional two-phase asphalt-aggregate model for better reflecting the separate addition of warm-mixing additives during mixing. Afterwards, the influence of aggregate type, asphalt type, aggregate moisture content, warm-mixing agent type, and the warm-mixing process on the moisture susceptibility of WMA is analyzed utilizing the models and indicators proposed. Finally, the validity of the SFE indicator is verified by comparing the calculation of effective adhesion work with freeze-thaw splitting test results. The results show that all of the above factors impact the moisture susceptibility of WMA by influencing the interfacial adhesion, with the effect of moisture content being the most significant. Meanwhile, effective adhesion work and the three-phase model brought out in this research are proven to be feasible to characterize the adhesion properties of WMA, offering theoretical support to the research on warm-mixing technology.
温拌技术的应用通过降低温拌沥青混合料（WMA）生产过程中的拌合温度带来了可观的经济和环境效益。然而，可能存在的水分残留也引发了对其水敏感性的担忧。为了深入研究WMA水敏感性的影响因素和作用机制，本研究采用了表面自由能（SFE）测试和室内试验。提出了一种基于SFE的新型指标，即有效粘附功，用于评估不同含水量下沥青与集料的粘附性。然后，考虑干拌法的拌合过程，引入了一种先进的三相模型，以沥青-集料-温拌添加剂的形式，改进了传统的沥青-集料两相模型，以便更好地反映温拌添加剂在拌合过程中的单独添加情况。之后，利用所提出的模型和指标，分析了集料类型、沥青类型、集料含水量、温拌剂类型以及温拌工艺对WMA水敏感性的影响。最后，通过将有效粘附功的计算结果与冻融劈裂试验结果进行比较，验证了SFE指标的有效性。结果表明，上述所有因素均通过影响界面粘附性来影响WMA的水敏感性，其中含水量的影响最为显著。同时，本研究提出的有效粘附功和三相模型被证明可用于表征WMA的粘附性能，为温拌技术的研究提供了理论支持。
