Impact of vertical porosity distribution on the permeability of pervious concrete

• Vertical permeability distribution calculated from vertical porosity distribution.
• Revised form of porosity–permeability relationship proposed.
• Effective permeability calculated from vertical permeability distribution.
• Effective permeability correlates to actual better than existing methods.
• Minimum permeability (therefore porosity) in distribution tends to control.

Though the presence of a vertical porosity distribution in porous pavements has been recognized, the impact of this distribution on the permeability of the pavement has not been considered. This research investigates the impact of a vertical porosity distribution on the overall permeability of pervious concrete. First, an unimpaired porosity–permeability relationship was generated using pervious concrete specimens which had uniform porosity throughout. This relationship was then used in conjunction with the vertical porosity distribution of surface compacted pervious concrete specimens to generate a vertical permeability distribution. An effective permeability value was used to summarize the overall behavior of the permeability distribution and was shown to have a much better correlation with the actual permeability of the specimens than the permeability predicted using the average porosity of the specimen. Additionally, an analysis of the relationship between the permeability distribution and the effective permeability showed that the minimum permeability (and therefore minimum porosity) tends to have the largest impact on the effective permeability.