3D modelling of heat transfer and moisture transport in young HPC structures with hybrid finite elements

Simulation of the hygro-thermo-chemical process of cement hydration in high-performance concrete (HPC) is performed coupling heat transfer with moisture transport, and accounting for an internal heat source and a moisture sink designed to simulate the chemical reactions developing in HPC structures. The three-dimensional finite element formulation is based on the direct approximation of temperature and relative humidity (RH) in the element domain. The heat and moisture flux fields are independently approximated on its boundary. Naturally hierarchical bases are used to set up these approximations to enhance adaptive refinement, while the geometry of the element is described independently to enhance the use of coarse, unstructured meshes. The solving system is sparse and well suited to parallelization. The relative performance of the formulation is illustrated using testing problems supported by experimental data. •The hygro-thermo-chemical process in concrete structures is adequately simulated using 3D hybrid finite elements.•The geometry is fully uncoupled from the approximation of the state variables.•Independent, naturally hierarchical and orthogonal approximation bases are well-suited to adaptive p-refinement.•The hybrid formulation implemented simple, coarse mesh with relatively high aspect-ratio elements.