Peng Chao, Yang Hanneng, You Zhanping, Ma Hongchao, Xu Fang, You Lingyun, Diab Aboelkasim, Lu Li, Hu Yudong, Liu Yafeng, Dai Jing, Li Zhibo
Faculty of Engineering, China University of Geosciences, Wuhan 430074, China.
Department of Civil and Environmental Engineering, Michigan Technological University, Houghton, MI 49931-1295, USA.
Materials (Basel). 2022 Aug 27;15(17):5930. doi: 10.3390/ma15175930.
Compared with traditional hot mix asphalt (HMA), wax based warm mix asphalt (WWMA) can be mixed with the aggregate at a lower temperature and achieve the desired compaction. However, the adhesion performance of WWMA on aggregate is uncertain. To evaluate the adhesion performance of asphalt and aggregate, researchers used contact angle test, pull-off test, and ultrasonic washing experiments. However, these tests cannot adequately explain the microscopic mechanism of the interface between asphalt and aggregate. Molecular dynamics (MD) can better explain the adhesion mechanism of asphalt aggregates because they can be simulated at the molecular scale. So, the purpose of this research is to use the MD method to study the adhesion performance between WWMA and aggregate. Two aggregate oxides (CaCO and SiO) models, the matrix asphalt model and WWMA models, were built in Materials Studio (MS) software. The adhesion work of asphalt and aggregate oxides was calculated. With the increase of wax modifier content, the adhesion work of asphalt and aggregate oxides (CaCO and SiO) first increases and then decreases. When the wax modifier is increased to 3 wt%, the adhesion works of the WWMA-SiO and WWMA-CaCO increase by 31.2% and 14.0%, compared with that of matrix asphalt. In this study, the accuracy of the MD calculation result was verified by the pull-off experiments and the contact angle experiments. WWMA was prepared by a high-shear mixer emulsifier. In the pull-off experiments and the contact angle experiments, the tensile strength and the adhesion work between the aggregate and the asphalt containing 3% wax modifier reaches peak values. These values are 140.7% and 124.9%, compared with those between the aggregate and the matrix asphalt. In addition, the results of the pull-off experiments and the contact angle experiments are in good agreement with that of the MD simulation. Finally, Fourier transform infrared spectroscopy (FTIR) shows that the carbonyl content of WWMA is greater than that of matrix asphalt. It explains well that the wax modifier promotes the adhesion between asphalt and aggregate. This paper provides an important theoretical basis to understand the adhesion performance of WWMA and aggregate.
与传统热拌沥青（HMA）相比，蜡基温拌沥青（WWMA）能够在较低温度下与集料混合，并实现所需的压实度。然而，WWMA与集料之间的粘附性能尚不确定。为了评估沥青与集料的粘附性能，研究人员采用了接触角试验、拉拔试验和超声清洗实验。然而，这些试验无法充分解释沥青与集料界面的微观机制。分子动力学（MD）能够更好地解释沥青集料的粘附机理，因为可以在分子尺度上进行模拟。因此，本研究的目的是利用MD方法研究WWMA与集料之间的粘附性能。在Materials Studio（MS）软件中建立了两种集料氧化物（CaCO和SiO）模型、基质沥青模型和WWMA模型。计算了沥青与集料氧化物的粘附功。随着蜡改性剂含量的增加，沥青与集料氧化物（CaCO和SiO）的粘附功先增大后减小。当蜡改性剂增加到3 wt%时，与基质沥青相比，WWMA-SiO和WWMA-CaCO的粘附功分别增加了31.2%和14.0%。在本研究中，通过拉拔试验和接触角试验验证了MD计算结果的准确性。WWMA由高剪切混合乳化剂制备。在拉拔试验和接触角试验中，集料与含3%蜡改性剂的沥青之间的拉伸强度和粘附功达到峰值。与集料和基质沥青之间的值相比，这些值分别为140.7%和124.9%。此外，拉拔试验和接触角试验的结果与MD模拟结果吻合良好。最后，傅里叶变换红外光谱（FTIR）表明，WWMA的羰基含量大于基质沥青。这很好地解释了蜡改性剂促进了沥青与集料之间的粘附。本文为理解WWMA与集料的粘附性能提供了重要的理论依据。
