多孔沥青混合料渗水性能的方向差异性及其受孔隙结构的影响

Directional difference of water permeability of porous asphalt mixture and influence of pore structure

为了分析多孔沥青混合料渗水性能的方向差异特征及其受连通孔隙结构的影响规律,通过自行研发的渗水仪测试了4个空隙率下OGFC-13和OGFC-10混合料试件空间24个方向上的渗水系数.结合CT扫描和图像处理方法,重构了4个空隙率下OGFC-13混合料试件的三维孔隙结构.提取连通孔隙后,分析了影响混合料渗水方向差异性的孔隙结构指标.结果表明:多孔沥青混合料渗水系数存在明显的方向差异性,竖向截面内水平方向上的渗水系数最大;水平截面也存在方向差异性,但其与方向之间的关系不明确;空隙率越大,采用集料的公称最大粒径越大,则方向差异性越小;相比水平向连通孔隙,混合料内部竖向孔隙的水力直径虽略大,但数量少且总长度短,这是影响渗水系数方向差异性的主要原因.

To analyze the directional difference of water permeability of porous asphalt mixture and the influence of pore structure,a self-developed permeameter was used to measure the permeability in twenty-four directions of OGFC-13 and OGFC-10 with four air void contents.The three-dimensional(3D)pore structure of OGFC-13 with four air void contents was reconstructed by using computed tomography(CT)technology and image processing.After the interconnected pores were extracted,the pore structure index which affects the water permeability directional difference of mixture was analyzed.The results show that the permeability of porous asphalt mixtures has an obvious directional difference.In the vertical plane,the maximum value of permeability occurs in the horizontal direction.In the horizontal plane,the permeability has a directional difference,but has no obvious relationship with directions.The increase of the air void content and the nominal maximum aggregate size can reduce the directional difference.Compared with the horizontal interconnected pores,vertical pores in mixtures have a larger hydraulic diameter,less quantity and length,which is the main reason for the water permeability directional difference of porous asphalt mixture.