粗集料棱角性对沥青混合料抗拉性能影响的虚拟试验研究

Virtual experimental study on the effect of coarse aggregate angularity on tensile performance of asphalt mixtures

为评价粗集料形态特征对沥青混合料抗拉性能的影响,结合CT扫描技术和有限元方法建立虚拟间接拉伸试验。通过虚拟试验对不同类型沥青混合料的间接拉伸劲度模量和粗集料运动轨迹进行仿真分析,建立粗集料棱角性与其抗拉性能及运动轨迹的相关关系。研究结果表明:粗集料棱角性指标与沥青混合料间接拉伸劲度模量之间存在一定的正相关性,与粗集料平均平动位移量及平均主轴方向增量存在一定的负相关性,但是其相关关系均依赖于级配类型。与AC-20混合料相比,AC-13混合料粗集料棱角性指标略小且分布更为集中,试验后其粗集料普遍产生了更大幅度的平动和转动变形,从集料形态特征和运动轨迹角度均证实其具有更优的抗拉性能。

The computer tomography scanning technique and finite element method were used to develop the virtual indirect tensile test to evaluate the effect of coarse aggregate morphology on tensile performance of asphalt mixtures.The indirect tensile stiffness and aggregate movement track of asphalt mixtures were simulated.Correlations between coarse aggregate angularity and tensile performance or movement track were obtained.It is found that the angular index of coarse aggregates positively correlate with the indirect tensile stiffness and negatively correlate with the average translation displacement and average increment of the principle axis direction.However,correlations were dependent on gradation types.Compared with the AC-20 mixture,the angular index values of the AC-13 one is slightly lower and the distribution is more concentrated.There are larger translation and rolling displacements for coarse aggregates of the AC-13 mixtures after testing,which is proved to have better tensile performance from the perspective of aggregate shape characteristics and movement track.