An exploratory study on correlating the permeability of concrete with its porosity and tortuosity

Permeability of concrete is often used as a key material property for assessing its durability. For a porous material in general, permeability depends upon the pore characteristics (i.e. porosity and tortuosity of pore channels). In this study, an attempt has been made to observe the relationship between pore characteristics and permeability of concrete. Data pertaining to porosity, tortuosity and permeability of concrete were typically obtained by testing different concrete mixtures prepared with varying water/cement ratios, cement contents and coarse/fine aggregate ratios. The experimental data were used to explore the correlation between pore characteristics and permeability of concrete. The results show that a correlation exists between the porosity/tortuosity ratio and the permeability of concrete, the coefficient of permeability increasing with increasing porosity/tortuosity ratio. The experimentally observed correlation bears resemblance to Kozeney's theoretical formation of intrinsic permeability in which permeability is expressed as a function of the porosity/tortuosity ratio.