Simulation-Based Characterization of Concrete and Cementitious Composites at Multiple Scales

The poster presents a micromechanics modelling approach used for different applications.

• Alkali-Silica Reaction (ASR) is a detrimental expansive reaction in concrete structures, such as dams and pavements, which substantially limits their structural lifetime. Silica present in the aggregates reacts with calcium, hydroxyl and alkali ions of the pore fluid to form a hydrophilic alkali-silica gel. The gel fills pre-existing microcracks in the aggregates and the cement paste and swells in the presence of moisture. The gel pressure induced microcrack growth manifests itself as an expansion at the macroscale. In order to predict the damage and expansion in a concrete pavement a multiscale modelling approach is adopted.
• Mechanized tunneling in difficult geological conditions, such as soils with significant swelling potential due to water uptake by the clay minerals, depends on the ability of the tunnel lining to tolerate localized swelling pressures. In order to avoid the risk of damage to the tunnel lining, additional radial layers such as a compressible tunnel lining segment can be incorporated. The deformation capacity of such compressible cementitious layer materials can be enhanced by introducing air voids and/or weak inclusions (Expanded Polystyrene (EPS), Expanded glass beads). Design of the composite materials for specific ground conditions can be obtained using a multiscale model-based framework.