A hierarchical multi-scale modeling approach to determine the thermo-physical properties of cement-based materials

Abstract This study introduces the Hierarchical Multi-scale Modeling of Computational Concrete (MuMoCC), a novel numerical framework designed to assess the thermal behavior of cement-based materials, specifically cement paste and mortar. The methodology involves two modeling scales—micro (cement paste) and sub-meso (mortar)—using Representative Elementary Volumes (REVs). At the microscale, cement hydration is simulated using CEMHYD3D, and phases are mapped onto a 3D mesh via the Take-and-Place method. At the sub-meso scale, sand grains are embedded in the mesh while the remaining volume is treated as cement paste. Thermal conductivity, specific heat, and coefficient of thermal expansion (CTE) are evaluated across three degrees of hydration (0.27, 0.55, 0.83) and five saturation levels (0%, 25%, 50%, 75%, 100%). The results reveal that thermal conductivity is highly dependent on hydration at low saturation levels but converges at full saturation, while specific heat is mainly influenced by saturation, exhibiting a distinct minimum between 50% and 75%. These findings underscore the advantages of numerical simulations over experimental techniques, which are typically limited to fully dry or saturated conditions. CTE results are consistent across both coupled and sequential simulation approaches, offering flexibility for future applications. The results are also in agreement with literature experimental results and show a decrease of the CTE when the hydration degree increases. The MuMoCC framework contributes thus a robust and extensible modeling tool for the research community, with potential to support the design of advanced cement-based materials incorporating novel or supplementary constituents.