Search

Chemical reactions can lead to the expansion of the geomaterial because of the strong precipitation of minerals in the pores of the medium. The quantity and the variability of these reactions led to the development of several chemo-mechanical models. A generic chemo-poromechanical model is proposed to predict both the material degradation induced by various concrete pathologies and the environmental multi-factor impact on the macroscopic swelling. The model is based on the coupling between reactive transport (species diffusion and chemical reactions) and poromechanics. The mineralogy and the poromechanical properties are estimated by a hydration-micromechanics model which allows to consider the material effects. The main applications are dedicated to External Sulfate Attack and Delayed Ettringite Formation of cementitious material at mesoscale. The studies highlight the ability of the model to deal with complex and various phenomena such as coupling chemical reactions with calcium leaching, sulfate sorption and ettringite precipitation, and to consider their impact on the macroscopic expansion. Results also bring out the accuracy of the chemo-poromechanical model to simulate different swelling pathologies. The characteristic crack paths induced by differential strain, material impact, and swelling at the macroscopic scale, fit with experimental observations. [ABSTRACT FROM AUTHOR]

Reactive transport modeling has become widely used to help improve understanding of hydrogeochemical processes from the pore scale to the watershed scale. In recent years, the scope of reactive transport applications has increased toward a higher level of complexity and process coupling. For example, the production and consumption of water as well as porosity evolution associated with the dissolution and precipitation of hydrated minerals can impact system evolution. Waste rock weathering, carbon sequestration, or the degradation of engineered barriers in radioactive waste repositories all constitute applications in which geochemistry and hydrodynamics can strongly influence each other. For these purposes, the traditional formulation of reactive transport simulators, which decouples groundwater flow and reactive transport processes, is limited. We present a global implicit compositional approach, which integrates the flow processes directly into the reactive transport and geochemical framework. This approach solves the flow field implicitly with the reactive transport equations, simultaneously accounting for water consumption and production due to geochemical reactions. Applications show that the model allows tackling complex reactive transport problems while accounting for intra‐aqueous reactions, redox reactions, and reactions involving mass transfer with the gas and solid phases. The presented simulations also demonstrate that the compositional and traditional approaches yield similar results for complex geochemical systems with relatively low reactivity. Key Points: A new global implicit approach for reactive transport modeling is presentedPressure evolution is linked to a water conservation equation which is intrinsically coupled with the reactive transport equationsThe method is validated for one‐dimensional cases with complex geochemistry [ABSTRACT FROM AUTHOR]