Use of a multi-species reactive transport model to simulate chloride ingress in mortar exposed to NaCl solution or sea-water

摘要

Simulations of ion ingress in Portland cement mortar using a multi-species reactive mass transport model are compared with experimental test results. The model is an extended version of the Poisson-Nernst-Planck equations, accounting for chemical equilibrium. Saturated mortar samples were exposed after 8 days of hydration to a NaCl-solution or natural sea-water in a laboratory controlled environment for the experimental part. The samples were analyzed for the total chloride content after 21, 90 and 180 days of exposure, at varying depths from the exposed surface. The applicability of the reactive mass transport model is shown by comparing the simulation and experimental results. The tortuosity factor used in the simulations is adjusted to obtain the best reproduction of the experimental results. The model predicts the total chloride content satisfactorily, despite assumptions in the simulation like fixed hydration degree over time. Improvements and suggestions for further development of the model are discussed, e.g. extended hydration description, improved overall chemical description and a more strict use of the tortuosity factor. (C) 2015 Elsevier B.V. All rights reserved.