Reactive transport modeling of CO2 through cementitious materials under CO2 geological storage conditions

Abstract

RésuméUn modèle de transport réactif est proposé pour simuler la réactivité des matériaux à base de ciment en contact avec une saumure saturée en CO 2 et/ou le CO 2 supercritique (CO 2 sc) dans les conditions de stockage géologique du CO 2 . Un code a été développé pour résoudre simultanément le transport et la chimie par une approche globale couplée, compte tenu de l'effet de la température et de la pression.La variabilité des propriétés du CO 2 sc avec la pression et la température, telles que la solubilité dans l'eau, la densité et la viscosité sont pris en compte. On suppose que tous les processus chimiques sont en équilibre thermodynamique. Les réactions de dissolution et de précipitation de la portlandite (CH) et Ce modèle est en mesure de simuler les processus de carbonatation des matériaux à base de ciment, dans des conditions à la fois saturés et insaturés, dans une large plage de concentration de CO 2 , de température et de pression. Plusieurs expériences, rapportées dans la littérature, sont simulées en utilisant divers types de conditions aux limites: (i) solutions saturées ou non en CO 2 et carbonate de calcium, (ii) gas supercritique de CO 2 . Les prédictions sont comparées avec les observations expérimentales. Certains II phénomènes observés expérimentalement peuvent être également expliqués par le modèle. Mots-clés:Carbonatation, CO 2 supercritique, Transports, Ciment, C-S-H, Décalcification, Pression, Température, Stockage du CO 2 . AbstractA reactive transport model is proposed to simulate the reactivity of cement based material in contact with CO 2 -saturated brine and supercritical CO 2 (scCO 2 ) under CO 2 geological storage conditions. This code is developed to solve simultaneously transport and chemistry by a global coupled approach, considering the effect of temperature and pressure.The variability of scCO 2 properties with pressure and temperature, such as solubility in water, density and viscosity are taken into account. It is assumed that all chemical processes are in thermodynamical equilibrium. Dissolution and precipitation reactions for portlandite (CH) and calcite (CC) are described by mass action laws and threshold of ion activity products in order to account for complete dissolved minerals. A chemical kinetics for the dissolution and precipitation of CH and CC is introduced to facilitate numerical convergence. One properly chosen variable is able to capture the precipitation and dissolution of the relevant phase. A generalization of the mass action law is developed and applied to calcium silicate hydrates (C-S-H) to take into account the continuous variation (decrease) of the Ca/Si ratio during the dissolution reaction of C-S-H. The changes in porosity and microstructure induced by the precipitation and dissolution reactions are also taken into account.Couplings between transport equations and chemical reactions are treated thanks to five mass balance equations written for each atom (Ca, Si, C, K, Cl) as well as one equation for charge balance and one for the total mass. Ion tran...

Thermodynamic of incongruent solubility of C–S–H

“…The method presented here was employed in the numerical simulation of various problems where dissolution of calcium silicate hydrate occurs (Shen et al, 2013;Yuan et al, 2013). In such simulations, mass balance equations must be solved.…”

“…This can be done directly through the characteristic curve of Equation 31 without additional numerical computations. For the silicon mass balance equation, the silicon content in the solid phase can be used as the primary unknown and Equation 35 as a complementary law to compute the silicon concentration in the aqueous phase (see Shen et al (2013) and Yuan et al (2013) for more details).…”

“…As a result of equilibrium, the Gibbs energy minimisation associated with the dissociation reaction of calcium silicate hydrate provides two new state laws that have not been explored thus far. Practically, this description of equilibrium between calcium silicate hydrates and their solutions can be easily implemented in durability models using a simultaneous computational approach between chemistry and transport, as has already been proposed in a description of the action of rich carbon dioxide environments on cement-based materials (Shen et al, 2013).…”

The effect of random porosity field on supercritical carbonation of cement-based materials

“…In the recent years, however, the researchers in this area have paid more attention on studying the beneficial aspects of material carbonation, due to the rapid development of the accelerated and supercritical carbonation techniques. These researches include modification of composition and microstructure of cement based materials using carbonation [7][8][9] , use of CO 2 curing to improve material properties [10,11] , CO 2 capture and storage [12] and carbonation of hazardous water materials [13] . Clearly, further research on the carbonation process of cement and concrete is required in order to maximize the benefits and reduce the negative effects caused by carbonation.…”

“…Carbonation of cement based materials is a complex multi-physics process [12,[14][15][16][17] , involving chemical reactions of CO 2 with CH and C-S-H; gas-liquid two phase flow; dispersion and diffusion of CO 2 in water; and temperature propagation. It is also a chemical-physical process of, e.g., calcium leaching and calcite precipitation.…”