Examination of Pervious Pavement Pore Parameters with X-Ray Tomography

Pervious pavement (PP) is an infrastructure material that can alter rainfall-runoff relationships, filter particulate matter (PM), and sequester runoff constituents. Beyond a measure of total porosity ( ϕt), less-commonly measured pore parameters and relationships thereof influence these phenomena. In this study, cementitious PP (CPP), used as a permeable surface for an exfiltration system loaded by runoff, was examined. X-ray tomography (XRT) was utilized to examine pore size and frequency, generate a total-to-effective porosity (ϕt − ϕe) relation- ship, quantify pore tortuosity (Le=L), and relationships for specific surface area (SSA), pore-size distributions ðPSDÞpore, and ϕt. Gravimetric analyses were used for SSA based on mass ðSSAÞs as well as validation of XRT porosity. Results indicate that ϕt ranged from 10 to 30% while ϕe ranged from 4 to 27%. Relationships for (ϕt − ϕe), SSA, ϕt, and median pore diameter (d50n) were represented with a power law model (PLM). Using ϕt the ðSSAÞpt of pores ranged from 11,000 to 19,000 m2=m3 while for ϕe, ðSSAÞpe ranged from 12,000 to 21,000 m2=m3. XRT results show that the ðPSDÞpore is hetero-disperse. (Le=L) ranged from 2.9 to 5.9, compared to 1.4 for a monodisperse and uniform distribution of pore sizes. The ðLe=LÞ-ϕt relationship and probability density function (pdf) of (Le=L) were Gaussian. Beyond the common index of ϕt, these parameters are building blocks for infiltration, filtration, evaporation, storage, and reaction components of models such as the storm water management model (SWMM) and computationalfluid Dynamics (CFD)