分子动力学模拟老化沥青的再生机理

左贵强，朱晓东，刘晋周，何佳

摘要:

再生沥青路面(RAP)在使用过程中,通常会使用再生剂来保证其整体性能。然而,关于再生剂在RAP中的再生机理,很少有原子尺度的解释。本文主要聚焦老化沥青再生行为的原子建模,分别构建了三种类型的沥青模型(新沥青、老化沥青和再生沥青),对比分析了其热力学、玻璃化转变行为、自由体积、自扩散和原子结构。结果表明,掺加10%再生剂后,老化沥青的自由体积增加了4.43%,玻璃态转变温度降低了11.82℃。再生剂通过增加RAP粘结剂的内聚力,以提高其抗裂性。沥青氧化老化后形成致密且平行堆积的沥青质结构,再生剂的引入起到解聚作用,扭转老化的负面影响,恢复粘结剂的微观结构,从而恢复其部分性能。

Abstract:

SRejuvenators are normally applied to guarantee the overall properties when reclaimed asphalt pavement (RAP) is used. However, there are few atomic-scale interpretations on the rejuvenating mechanism of rejuvenator in RAP. This study focuses on the atomic modeling of rejuvenation behavior of oxidized asphalt. Three types of asphalt models (virgin, aged, and rejuvenated asphalt) were constructed respectively for comparative analyses of thermodynamics, glass transition behavior, free volume, self-diffusion, and atomic structures. Results denote a 4.43% increment of free volume and an 11.82 °C decrease of glass transition temperature in aged asphalt is observed after blending with 10% rejuvenators. Rejuvenators increase the cohesion of RAP binder to improve its cracking resistance. A dense and parallelly stacked structure of asphaltene is formed after oxidative aging. The introduction of rejuvenators plays the role of de-agglomeration, reversing the negative effects of aging to restore the microstructure of binder thereby recovering part of its properties.