A nearly self-sufficient framework for modelling reactive-transport processes in concrete

Abstract

This paper describes a multi-species and multi-mechanism reactive-transport modelling framework for concrete. This modelling framework has the potential to be used in conjunction with performance specifications currently being developed in the US. The modelling framework is 'nearly' self-sufficient as it enables electrical resistivity to be used as the main physically measured input parameter in the simulations. The model uses thermodynamic calculations to predict pore solution composition, pore solution resistivity, pore volumes, and reactions between the solid and ionic components of the cementitious matrix such as chloride binding. The measured electrical resistivity is normalized by the calculated pore solution resistivity to compute the formation factor, which is used to predict transport properties of the ionic species. The framework allows the solution of reactive-transport equations with minimal input data to assess ionic movement, chloride ingress, and time to corrosion.

Reinforced concrete structures: A review of corrosion mechanisms and advances in electrical methods for corrosion monitoring

“…It is also possible to combine the formation factor with Langmuir or Freundlich adsorption isotherm, and to predict either chloride ingress with the Nernst-Planck equation [308,309] or the apparent chloride diffusion coefficient in concrete [310]. The use of concrete resistivity therefore is a good indicator of the concrete durability in terms of ion diffusivity and fluid transport [311][312][313].…”

Application of thermodynamic modelling to hydrated cements

“…Thermodynamics is also an invaluable tool for assessing the durability of a cement paste in a given environment. The coupling of thermodynamic modelling with transport codes makes it possible to calculate the degradation of cement in contact with the environment [16,[168][169][170][171][172][173] and with sodium chloride [174,175]. Transport modelling becomes the only possible mean of estimating the durability of cementitious materials in very long timeframes in some critical applications such as stabilisation and solidification of radioactive wastes [17,170,172].…”

Solubility and speciation of iron in cementitious systems

“…Another possible cause for steel corrosion in concrete is carbonation of the cementitious phases and the associated loss in pH buffering capacity of the matrix surrounding the steel [13,14]. Motivated by these causes for corrosion, the modelling of chloride ingress and concrete carbonation in concrete has been a subject of research for a long time as evidenced by a range of ever-evolving (reactive) transport models for quantifying the space-time evolution of species that initiate corrosion of reinforcement [15][16][17][18]. However, comparatively little research has been devoted to fundamentally understanding and modelling the transport and reaction processes of the iron species that are released into the cementitious matrix after corrosion initiation.…”

“…First, it is well known that the corrosion kinetics of a metal is strongly influenced by mass transport in the electrolyte around the metal surface [19][20][21][22]. Second, the transport and precipitation of iron species in the cementitious matrix surrounding the steel are important steps that need to be considered in predicting corrosion-related damage of concrete structures, such as cracking and spalling [3][4][5]7,8,18,[23][24][25][26].…”