Carbon sequestration in cementitious materials using living organisms
Responsible: Luka Malenica
Background
Understanding moisture transport through porous materials is of great importance in a wide range of processes and essential field of study in a broad range of applications. One of the processes where moisture state plays a crucial role is corrosion of metal inside porous materials, such as concrete or soil. The moisture distribution in such materials is directly related to corrosion mechanisms and has great impact on durability of any reinforced structure.
Prediction of water transport and retention throughout such a complex pore system is usually based on traditional models relying on a homogenization approach and requires different macroscopic properties such as porosity, permeability, and tortuosity. However, some porous materials, like cement-based materials, show disagreement between the experimental data and traditional models making them unreliable. Furthermore, traditional models are not capable providing detailed insight of moisture distribution at the steel-porous media interface which is crucial to understanding of relevant degradation mechanisms such as corrosion.
In recent years, the pore scale modeling of multiphase flow has received significant attention and started to be used as a predictive tool in many different porous media applications. These models account for complex microstructure heterogeneities and together with pore scale experiments have potential to improve our understanding of multiphase flow processes and lead development of improved upscaled models by connecting microscale mechanisms with macroscopic properties required for practical large-scale modeling. In the context of cementitious media and their interaction with steel surface, application of pore-scale modeling is still limited and yet an emerging tool.
Aims and objectives
The aim of this project is to combine pore scale modeling with real 3D pore structures to study moisture transport and retention inside realistic porous materials. The special interest will be on moisture distribution at the interface of porous materials and metal surface.
Thus, the pore scale structures imaged by Neutron or X-ray μCT and FIB-SEM techniques will be used to account for complex microstructure heterogeneities of porous materials while high-fidelity multiphase flow computational fluid dynamics simulations will be applied to model fully (interface) resolved gas-liquid flow inside realistic porous geometries. Primary focus will be on concrete and sandstone media. Different material and fluid properties as well as different exposure conditions and processes relevant to steel corrosion will be investigated.
Methodology
Among different computational methodologies used for investigation of the multiphase flow at pore scale, our focus is on direct pore scale modeling. This approach has the highest level of complexity since it preserves the microstructure of the pore-space geometry. High-resolution microtomography and FIB-SEM imaging techniques are used to characterize complex pore space geometries while grid-based finite volume solver is used to get insight into relevant physical processes of multiphase flow in complex 3D geometries ranging from nano- to micro-meter scale resolution.