Correlating the chloride diffusion coefficient and pore structure of cement-based materials using modified noncontact electrical resistivity measurement

The electrical resistivity of hardened cement-based materials was measured in this work by a modified noncontact electrical resistivity measurement (MN-CM). The resistivity was further processed to compute the chloride diffusion coefficient (D _ρ ) using the Nernst-Einstein equation. Also, the rapid chloride migration test (RCM) was carried out to obtain the chloride migration coefficient (D _RCM ), and the relationship between D _ρ and D _RCM has been established. The obtained D _ρ was further correlated to the pore structure parameters characterized by low-field nuclear magnetic resonance (NMR) spectroscopy. The results show that the D _RCM is more sensitive to the change of pore connectivity, while D _ρ is more sensitive to the change of porosity. The D _ρ is smaller than D _RCM since it strictly follows the Nernst-Einstein equation while RCM neglects the other driving forces such as capillary sorption and concentration gradient. It is concluded that the proposed MN-CM can obtain the chloride diffusion coefficient of saturated cement-based materials in a quick, stable, and reliable manner.