Determination of water permeability of cementitious materials using a controlled constant flow method

Permeability is a fundamental material property for characterizing concrete durability because it determines the penetration of aggressive substances responsible for degradation under a pressure gradient. However, measuring permeability of cementitious materials is not a trivial task as is discussed in this paper by an extended review of both direct and indirect permeability measurement methods. This work describes a direct method to determine the permeability of cement-based materials. The novelty of the method is that steady-state conditions are controlled by applying a constant water flow (controlled by a Syringe pump) rather than the applied pressure gradient because the measurement accuracy of the pressure is much higher of the extremely low flow. Two other advantages are that the method is relatively fast and flexible. Tests were performed on hardened cement pastes with water/cement ratio ranging from 0.4 to 0.6 to verify the proposed method. The validity of Darcy’s law was confirmed by the permeability measurements with various flow rates performing on leached limestone cement paste sample. The results showed that the proposed method is giving reliable results within a reasonable experimental time.