Thermal and water transfer in cementitious porous medium: thermal building and durability

Cementitious materials are typical porous medium, which are widely used in civil engineering and thermal buildings. The thermal and hydrate properties of the material are fundamental to predict accurately the energy needs and the reliable duration of the structures in a long term. Due to the complicated coupling, the thermal capacity, conductivity and source term in energy equation are affected by the humidity distribution and the microstructure evolution of the porous materials. The coupling relation of thermal and hydrate properties are summarized in this work, the coupled drying model is discussed, and the experiment is performed to verify the simulation results for RH (Relative humidity) and ML (Mass loss). Two approaches are adopted to estimate the humidity/water content profile in the porous medium and to analyse the temperature effect. In addition, the equivalent hydrate capacity and conductivity are identified as function of humidity. The significance of this work lies in predicting the energy demand, the long-term thermal behaviour, taking into account the change of the thermal cementitious materials properties during their service time. Such inner structure is consequence of the system durability where the temperature, water content and humidity will act on the cracks settling within the material.