The permeability coefficient of PA concrete samples was tested, and equations between permeability coefficient and void content were fitted linearly. Besides, this research mainly focused on the influence of several parameters obtained from interconnected pores on the drainage performance of PA concrete at last. Then, the volume and size distribution of the pores was analyzed. The voids on void images were identified and classified into three groups according to the three kind of pores (interconnected pore, semi-interconnected pore, and closed pore) and reshaped them into 3D pore structures according to the overlapping principle. Image dodging algorithm and OTSU method were conducted to deal with these CT images for segmenting them into three subimages (void image, asphalt mortar image, and aggregate image) according to the three components of PA concrete. Four samples were formed and scanned by CT equipment to obtain the internal cross-sectional CT images. This paper is aimed at researching the relationship between three-dimensional (3D) pore structures and drainage performance of PA concrete. It is of great practical significance to find out the relationship between void drainage capacity and air voids.
The internal air voids in PA pavement are the main functional structure that determines its drainage performance. The appearance of porous asphalt (PA) pavement is to solve the problem of road ponding in rainy days. This study provides a comprehensive understanding of the mechanical properties of PPUC and an initial insight into the mechanism of water damage. PPUC is more susceptible to water damage because water reacts with the residual isocyanate groups within the polyurethane film to generate carbon dioxide gas, which reduces the cohesion and adhesion performance of polyurethane film. The mechanical properties and water stability of PPUC were effectively improved by increasing the polyurethane dosage and using continuously graded aggregates. The results show that the flexural strength and Marshall stability of PPUC can more easily reach the index in the standards of porous cement concrete or porous asphalt, while the compressive strength and abrasion resistance are the weak points of its mechanical properties and need to be further optimized. In this study, the comprehensive mechanical properties and water stability of PPUC with different gradations and polyurethane dosages were investigated, and its water damage mechanism was preliminarily explored. However, studies of the mechanical properties of PPUC are still insufficient. Porous polyurethane concrete (PPUC) is a novel material for permeable pavements and is considered as an alternative to porous asphalt or porous cement concrete. This study provides promising results for improving N and P removal by modifying a porous asphalt pavement system to include an MZP-PM adsorbent column as a post-treatment. The formation of ≡(La)(OH)PO2 was verified to be the dominant pathway for selective phosphate adsorption by MZP-PM and ion-exchange was proved to be the main removal process for ammonium. This improvement was presumably due to MZP-PM’s high adsorption capacity and surface complexation. The PAP system of zeolite bedding incorporated into MZP-PM (a weight less than 5% of zeolite) removed 74.5% to 90.6% of ammonium (NH4+-N) and 72.9% to 92.4% of total phosphate (TP) from the influent, as compared with 25.7% to 62.7% of NH4+-N and 32.6% to 56.4% of TP by that of the limestone as bed material. Two laboratory-scale PAP systems were developed by comparing limestone bedding and zeolite incorporated into modified zeolite powder porous microsphere (MZP-PM) as a filter column under a typical rainfall. Porous asphalt pavement (PAP) system is a widely used treatment measure in sustainable stormwater management and groundwater recharge, but their variable performance in nitrogen (N) and phosphorus (P) removal requires further reinforcement prior to widespread uptake.