Xiao Bin, Cao Wei, Zhou Liang
School of Civil Engineering, Central South University, Changsha 410078, China.
Hunan Junjia Pavement Material Co., Ltd., Changsha 410000, China.
Materials (Basel). 2025 Apr 9;18(8):1722. doi: 10.3390/ma18081722.
The high-temperature rutting performance of asphalt mixtures is strongly dependent on the aggregate skeleton and particle movement under loading. Such mechanisms were addressed in the present study by a combined experimental and simulation approach based on the triaxial strength test. A single type of asphalt with two different aggregate gradations (dense and gap) was incorporated to highlight the role of gradation in resisting shear dilation. The simulation was carried out by coupling the discrete and finite element methods considering the realistic three-dimensional aggregate shapes and gradations as well as the flexible boundary prescribed by latex membranes as routinely employed in triaxial testing. In order to represent contact failure-induced cracks within the virtual specimens, the linear parallel bond model was mixed with the Burgers or linear model through random distribution at contacts involving the mortar units. Model verification was achieved by comparing the resulting stress-strain data against those from the laboratory. The calibrated model provided a platform for systematic investigation from the perspectives of particle movement, crack development and distribution, and interparticle contacts. The results showed that the gap-graded mixture yielded lower triaxial strengths and yet softened at a lower rate and exhibited smaller volumetric expansion in the post-peak region. A faster loss of internal cohesion was inferred in the dense-graded mixture based on the higher accumulation rate of cracks that were concentrated at the middle height towards the perimeter of the virtual specimen. Contact analysis indicated that aggregate skeleton was more influential in the strength and stability of gap-graded mixtures.
沥青混合料的高温车辙性能在很大程度上取决于集料骨架和加载下的颗粒运动。本研究通过基于三轴强度试验的实验与模拟相结合的方法来探讨这些机制。采用单一类型的沥青与两种不同的集料级配（密级配和间断级配），以突出级配在抵抗剪切膨胀中的作用。模拟通过耦合离散元和有限元方法进行，考虑了实际的三维集料形状和级配，以及三轴试验中常规使用的乳胶膜规定的柔性边界。为了在虚拟试样中表示接触破坏引起的裂缝，线性平行粘结模型通过在涉及砂浆单元的接触处随机分布与伯格斯模型或线性模型混合。通过将所得应力 - 应变数据与实验室数据进行比较来实现模型验证。校准后的模型为从颗粒运动、裂缝发展与分布以及颗粒间接触的角度进行系统研究提供了一个平台。结果表明，间断级配混合料的三轴强度较低，但软化速率较低，在峰值后区域的体积膨胀较小。基于集中在虚拟试样中部高度朝向周边的裂缝较高的累积速率，推断密级配混合料内部粘结力损失更快。接触分析表明，集料骨架对间断级配混合料的强度和稳定性影响更大。
