Predictive model for chloride penetration through concrete

Abstract

This work documents a numerical model, the objective of which is to predict the chloride penetration through saturated concrete. The model solves the Nernst–Planck/current law equations and accounts for the chloride interactions with the solid phase. In addition to boundary conditions, it requires a set of five experimental characteristics available from a single sample of material namely: density; porosity; pore solution composition; effective chloride diffusion coefficient; and chloride binding isotherm. The input data do not evolve with time; the exceptions are the ionic diffusivities, which are time dependent. The method used to obtain the input data is outlined. Particular attention is paid to the metrology of the unsteady state migration test, which makes it possible for the chloride diffusion coefficient to be measured. The manner in which the chloride binding isotherm is reached is emphasised. Finally, the method is validated by comparing the numerical simulations with experimental results made on a CEM-I-based concrete.

A variable-order time-fractional derivative model for chloride ions sub-diffusion in concrete structures

“…(2.9)) model, two benchmark experiments [14,12] will be used to validate the predicted chloride profiles produced by the present VOFD model.…”

“…Khitab et al [12] obtained a series of experimental results of chloride profiles in the saturated concrete samples based on the CEM-I-type cement with water-cement ratio of 0.4. For more details of these experiments please refer to [12].…”

“…For more details of these experiments please refer to [12]. In this study, we will use these measurement data to validate our proposed VOFD model by predicting concentration profiles.…”

“…Although the Nernst-Planck flux equation model [13,12,2] can well depict such diffusion processes with clear physical significance, its complicated expressions and many parameters severely impede its applicability. It is highly desired to develop a simple model with fewer parameters that can effectively describe such chloride ions diffusion processes in concrete.…”

Impact of the pore solution on the aqueous diffusion through porous materials

“…Most techniques rely still today on saturated samples [1,[4][5][6][7][8][9][10][11]. Yet, in-situ structures are hardly encountered in saturated state.…”