Changement climatique - Recherche française (avec laboratoires CNRS) - 2010-2015

A reactive transport model is proposed to simulate the reactivity of cement in contact with CO2-saturated brine and supercritical CO2 (scCO(2)). Dissolution and precipitation reactions for portlandite (CH) and calcite (C (C) over bar) are described by mass action laws and threshold of ion activity products in order to account for complete dissolved minerals. A generalization of the mass action law is derived from thermodynamics and applied to calcium silicate hydrates (C-S-H) to take into account the continuous variation (decrease) of the C/S ratio during the dissolution reaction of C-S-H. We assume thermodynamical equilibrium for chemical processes. The porosity changes induced by the precipitation and dissolution reactions are also taken into account. Ion transport is described by using the Nernst-Planck equation as well as advection. Couplings between transport equations and chemical reactions are treated thanks to several mass balance equations written for each atom. We simulate by a finite volume method some experiments reported in the literature and compare our numerical results to these experimental observations. (c) 2013 Elsevier Ltd. All rights reserved.