Comparison between the falling head and the constant head permeability tests to assess the permeability coefficient of sustainable Pervious Concretes

The use of Pervious Concrete (PC) increased in the last years as an alternative to solve the run-off problem. PC shows a high percentage of empty spaces/gaps, which vary from 10 to 35%, facilitating the flow of rain and water through its structure. PC presents higher k permeability coefficient compared to conventional concrete. Permeability is the main property of PC, although there is no standardized method that guarantees the correct and precise measurement of such property in laboratory conditions. Currently, two main methodologies are used to assess the permeability coefficient: the falling head and the constant head permeability tests. In that regard, the American Concrete Institute recommends the use of the first method, although no comparison was done between them. Furthermore, the recommendations do not consider the use of sustainable aggregates during the production of the PC. In this study, the permeability tests were explained and used to assess the permeability coefficient of different mixes of PC produced with sustainable aggregates. The experimental results were used to analyze the relationship between the porosity and the permeability of concrete and compare the performance of the falling head and constant head permeability tests. The study presents the advantages of performing the constant head permeability test to assess the permeability of the PC.