Computational modeling of hardening concrete at mesoscale

Date

2023-4-27

Author

Yılmaz, Çağlar

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Concrete can be conceived as a composite material made up of cement, fine and coarse aggregates, water, and admixtures. The strength gain mechanism of concrete is based on the exothermic chemical reactions between the cement and free water that are collectively referred to as hydration. Generally hydration is accompanied by various physico-chemical phenomena such as the evolution of temperature and water content, thermal and shrinkage-induced volumetric deformations. During the chemical aging of concrete residual stresses develop in the material, especially at the interface between the mortar and coarse aggregates. These residual stresses mainly arise from the constraining effect of aggregates due to their higher stiffness on the mortar. This work is concerned with the computational modeling of hardening concrete at the mesoscale to investigate the effect of the area fraction, segregation, aspect ratio, and the roundness of aggregates under the action of different magnitudes of shrinkage deformations in mortar on the magnitude of residual stresses. For this purpose, a virtual tool for generating the meso-structure of concrete is developed. The generated models at mesoscale are then analyzed numerically to calculate the evolution of principal residual stresses during early ages of samples. The hardened samples incorporating shrinkage-induced residual stresses are then analyzed under tension to examine the effect of the residual stresses on the tensile strength of concrete at mesoscale using the phase-field fracture method.

Subject Keywords

Constitutive equations, Hardening concrete, Mesoscale, Shrinkage, Phase- Field Method

URI

https://hdl.handle.net/11511/103230

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Graduate School of Natural and Applied Sciences, Thesis