Quantitative Characterization of Transport Properties in Roller-Compacted Concrete by Incorporating RCPT and TDR

This paper proposes a reconfiguration of the rapid chloride permeability test (RCPT) using a time-domain reflectometer (TDR) to quantify the transport properties of concrete. The current RCPT test requires soaking the specimens for $18\pm 2\mathrm{h}$ to facilitate the ionic movement during the test. A voltage source is constantly applied over a 6-h period, and the charge passed is measured to qualitatively interpret the penetrability of concrete specimens. In this study, oven-dry specimens were used to measure the time-dependent dielectric constant as a key output of the TDR measurements and characterize the actual ingress of the chloride solution over the 6-h test period. The measured dielectric constant was used in the self-consistent and complex refractive index (CRI) models to establish the volumetric solution content relationship with time. Furthermore, this relationship was employed to estimate the transport properties in terms of diffusion and permeability coefficients of roller-compacted concrete (RCC) specimens. It was also used to establish a relationship between the charge passed and the volumetric content of the solution. Test results showed that the diffusion coefficients of RCC specimens are in order of ${10}^{-8}{\mathrm{m}}^2/\mathrm{s}$, and permeability coefficients are in the order of ${10}^{-6}{\mathrm{m}}^2/\mathrm{s}$. Additionally, the charge passed exhibited a linear relationship with the volumetric content of the solution.