Predicting the Permeability of Pervious Concrete (Enhanced Porosity Concrete) from Non-Destructive Electrical Measurements

The effectiveness of a pervious concrete pavement to transport water through it depends on the intrinsic permeability of the system. However, this characteristic is usually defined in terms of the porosity of the material. It has been observed that porosity alone is an inadequate indicator of the permeability of pervious concretes, since the permeability depends on pore sizes, geometry and connectivity also. This paper presents a unique non-destructive method to determine the permeability of pervious concrete from electrical conductivity measurements. Combining the normalized electrical conductivity of pervious concrete determined using either alternating or direct currents with the porosity of the material, and applying it in a modified version of Kozeny-Carman equation, a new parameter called hydraulic connectivity factor is introduced. This factor can be thought of as a combination of parameters that describe the pore space volume and geometry in such a way that the intrinsic permeability is related to porosity and hydraulic connectivity factor. Using this factor, and the porosity, the hydraulic conductivity or permeability of pervious concrete is determined. The hydraulic connectivity factor also provides a means to classify pervious concretes based on their hydraulic characteristics. The permeability values predicted using this method have a strong correlation with the permeability measured using a falling head permeameter developed at Purdue University for pervious concretes.