The Effect of Loading on the Diffusivity of Chlorides in Mortar

This study focuses on the effect generated by a compressive load, in the range 15%-60% of the ultimate load (F_u), in the chloride penetration rate of cement-based materials. The modifications produced in the microstructure influence the transport properties, and, thus, the validation of several interesting parameters, such as, the load value and the loading time, including both static and dynamic loading modes, was evaluated. This analysis was performed by impedance spectroscopy (IS), a non-destructive technique that allowed, after the appropriate modeling analysis, the assessment of the resistivity of the sample, a parameter that has been correlated to the diffusion coefficient in a previous investigation. The experimental arrangement was designed to allow the recording of the impedance spectra under the effect of a compressive load and, thus, the real-time monitoring of the chloride diffusivity was provided. An increase in the diffusion coefficient was verified for a load at 60%F_u whereas no variations were obtained for the load fixed at 30%. A relevant difference could be checked if the values were measured once the load was removed, showing the importance of the precise loading stage for the chloride diffusion study.