Quantifying Three-Dimensional Macropore Structure and Seepage Characteristics of Representative Elementary Volume for Recycled Aggregate Pervious Concrete

Abstract

The permeability performance made of recycled aggregate pervious concrete with macropores (M-RAPC) relates greatly to the macropore structure and seepage behaviors. However, the mechanism of the influence of pore structure on the permeability of M-RAPC is still unclear. Based on the high-resolution X-ray computer tomography (CT) and image processing technology, a three-dimensional (3D) pore structure model with macropore (>0.15 mm) was constructed, and the dimension of the representative elementary volume (REV) was determined to be 450×450×450 voxel3. Then, the quantitative characterization of the topological structure of macropore space and the simulation of pore flow were conducted. Finally, the relationship between macropore structure parameters and seepage behavior was discussed. The results showed that about 80% of macropores are in the range of 0.15–1 mm, and the pore coordination number is mostly concentrated within 20. The macropore distribution shows a great spatial heterogeneity, showing that the permeability anisotropy index is mainly larger than 1, and even up to 8. Besides, the permeability performance of M-RAPC is significantly correlated with macropore parameters (effective porosity, tortuosity, and fractal dimension). In summary, this study can better reveal the relationship between pore structure and seepage behaviors in M-RAPC and provide a reference for the skeleton structure and permeability performance optimization design of M-RAPC.