Comparative study on the hydraulic conductivity of pervious concrete slabs by constant and falling head permeability tests

Stormwater management is still a major concern confronting many countries all over the world. The need to collect the runoff water is highly prioritised to save natural resources and restore groundwater supplies. Pervious concrete is a special type of concrete that possesses the unique characteristic of allowing water to pass through it. Hence, the study of the hydraulic characteristics of pervious concrete is highly required to understand the material’s ability and utilise it to the maximum. The main motive of this experimental investigation is to study the hydraulic conductivity of pervious concrete slabs using two different methods, namely the constant and falling head permeability tests. Seven different pervious concrete mix proportions were examined in this work. A total of 21 pervious concrete slabs of size 1000 mm × 1000 mm × 200 mm were cast with different degrees of compaction and tested for hydraulic conductivity. From each slab, three concrete cores of size 100 mm diameter × 200 mm height were drilled and extracted to test the hydraulic conductivity and to compare with the test results of the pervious concrete slabs. The test results revealed that compaction is the predominant factor that affects the hydraulic conductivity of the pervious concrete slabs. It has also been observed that all the pervious concrete slabs exhibited non-Darcian behaviour irrespective of the degree of compaction. From the results, it is clear that the hydraulic conductivity of the pervious concrete varies according to the test methods and hydraulic gradients. The results from the extracted cores exhibited similar trend behaviour of the concrete slabs, confirming the non-Darcian flow in pervious concrete. The results also showed that the estimated hydraulic conductivity by the constant head method was higher due to the lower hydraulic gradients considered during the experiment. The outcomes of the test results will be helpful in the rational design of pavements using pervious concrete.