Simulation of internal and external sulfate attacks of concrete with a generic reactive transport-poromechanical model

Abstract

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 diusion and chemical reactions) and poromechanics. The mineralogy and the poromechanical properties are estimated by a hydration-micromechanics model which allows to consider the material eects. 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 dierent swelling pathologies. The characteristic crack paths induced by dierential strain, material impact, and swelling at the macroscopic scale, t with experimental observations.

A coupled hydro-chemo-mechanical approach to model the degradation and appearance of cracks in cementitious materials subject to carbonation

“…Then, the damage initiation and propagation is influenced by the local chemical strain and macroscopic sample deformation, as described in 8,13 . Finally, due to the complex strain behavior, there is no linear combination between the normal crack opening and the damage fields.…”

“…There exists several mechanical approaches to describe the appearance and propagation of deformationinduced cracks. Cracks can be explicitly described through fracture mechanics models such as XFEM 103 or frictional cohesive zone models 13 , or can be included through a continuum approach such as damage mechanics 8 . However, with the perspectives of upscaling our approach to large structures or geological settings, continuum models accurately describing the evolution of macro-scale properties and structural damage are required.…”

“…The degradation of porous reactive materials is a prime example in which mechanical and chemical evolutions are coupled and exert a feedback on each other, often through the appearance or sealing of cracks. As examples, we can cite the chemical induction of fractures within lithium batteries 9 , the durability of geomaterials in the reservoir context 10,11 , or concrete 8,12,13 , melting of nuclear pellets 14 or the corrosion and hydrogen transport in steel 15 . On a larger scale, we can cite the durability of injection wells for gas reservoirs 16 or concrete dams 17,18 , the induced seismicity associated with various applications [19][20][21][22] .…”

“…For example, mineralogical evolutions obtained from reactive transport (RT) simulations were used to evaluate whether or not a mechanical failure could occur [23][24][25][26] or to compute the mechanical stress and strains without incorporating the appearance of cracks 10,27,28 . Also, RT simulations often neglect one or several processes which may have a significant effect on the mechanical response, such as the porosity evolution or the water balance (consumption, evaporation) 13,[29][30][31] .…”

Carbonation and Leaching Behaviors of Cement-Free Monoliths Based on High-Sulfur Fly Ashes with the Incorporation of Amorphous Calcium Aluminate

“…The quality of the potential supplementary cementitious materials can be evaluated with the chemical and mineralogical compositions of industrial wastes through various regulations and standards. − Fly ashes (FA) are widely known and utilized as supplementary and alternative cementitious materials. , Yet FA particle is only a few microns in thickness and can contain leachable toxic heavy metals and salts, which can limit the possibilities for the valorization of these materials. The SO 3 content in fly ashes (FAs) is a critical parameter, especially in high-sulfur fly ashes (HSFA), as a high sulfur content can lead to various adverse effects such as sulfate attack and reduced durability in cementitious systems. , These potential issues can significantly limit the utilization and applications of HSFA, despite its wide availability. Recycling of FAs or other types of out-of-furnace byproducts with high sulfur content − as supplementary cementitious materials requires compliance with legal standards, which can be complex and costly once the sulfur removal treatments are considered .…”