Construction of virtual interfacial transition zone (ITZ) samples of hydrated cement paste using extended stochastic optimization

초록

The interfacial transition zone (ITZ) in hydrated cement paste has highly modified microstructures near embedded materials such as aggregates. The ITZ has a significant influence on the properties of concrete (stiffness, strength, and permeability). This study proposes a framework for constructing virtual 3D ITZ microstructures with a porosity gradient as an alternative to real 3D ITZ microstructures. Virtual two-phase (pore/solid) 3D ITZ samples are reconstructed by extending the conventional stochastic optimization process for random heterogeneous materials. The virtual samples are reconstructed to reproduce probabilistic descriptions of pore microstructures of the ITZ. The pore microstructures are described by low-order probability functions obtained from synchrotron mu-CT images of bulk cement paste samples of varying porosities. The properties (stiffness, thermal conductivity) of the reconstructed samples were evaluated through virtual experiments, and the anisotropic properties correlate with characteristics of the microstructures. The proposed framework can be used as an accelerated ITZ performance evaluation tool.

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