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The relationship between porosity and permeability of concrete

Q. What is porosity and is it related to permeability of concrete?

 

A. Porosity is a measure of the volume of voids in concrete. Permeability is the rate of flow of moisture through concrete under a pressure gradient. Permeability depends not only on porosity but also on the connectivity of the pores. High porosity concrete might still have low permeability if the pores are not interconnected. Conversely, concrete with lower porosity but well-connected pores could have high permeability. For example, using aggregates of different sizes in pervious concrete to product the same porosity has resulted in different permeability values.

 

References: SP-1(02); ACI 201.1R-08; ASTM C1202

Topics in Concrete: Concrete Fundamentals; Durability; Permeability