Effects of parameters on vertical porosity distribution in pervious concrete

The vertical porosity profile of pervious concrete (PC) is dictated by various mix design parameters, including aggregate/cement (a/c) ratio, compaction type and effort. In the presented work, an attempt was made to reveal the profound impacts of these parameters on porosity and strength. Vertical profile analysis using image processing techniques revealed that a zone approximately 10-15 mm thick with high porosity was observed at the top and bottom ends of a cylindrical PC core (13-20% of total PC thickness in total). Total porosities in that zone were 20-42% and 35-60% for lower and higher a/c ratios, respectively. The middle span of 120-130 mm of the vertical profile showed porosity variations of 5-15% and 30-45% for low and high a/c ratios, respectively. Overall, the a/c ratio and compaction effort manifested a profound impact on the vertical porosity profile. Compaction types showed trivial impact on porosity and compressive strength properties of PC for a/c ratios from 3.0 to 5.0. The authors recommend that the findings of this study would help to obtain the required porosity profile in PC without compromising strength characteristics.