Pervious concrete: effects of porosity on permeability and strength

Pervious concrete needs to have many pores to achieve high water permeability, but excessive porosity may cause a serious reduction in strength. Herein, it is postulated that the interconnected porosity and open porosity, which can be separately measured, do not have the same effects on the performance of pervious concrete. To evaluate how the interconnected porosity and open porosity influence permeability and strength, a series of no-fines pervious concrete mixes with varying water/cement (w/c) ratio and paste volume were produced for testing of their interconnected porosity, open porosity, unsubmerged water permeability, submerged water permeability and compressive strength. From the test results, it was found that both the w/c ratio and paste volume have major effects on the porosity, permeability and strength. More importantly, regression analysis showed that the interconnected porosity is the governing factor determining the water permeability, whereas the open porosity and w/c ratio are together the governing factors determining the compressive strength. Lastly, the concurrent strength–permeability performance of the no-fines pervious concrete tested was evaluated.