A study of the apparent thermal conductivity of cement paste at very early age of hydration: An attempt of modelisations

International audienceThe measurement results of the apparent thermal conductivity of cement paste at very early stages ofhydration are described and an attempt of modelisations of these results is presented.The experimental method is based on the “hot wire” method. The results show an evolution of the apparentthermal conductivity of the cement paste at very early age. Two types of modelling are proposed to explain thisevolution: First, the apparent thermal conductivity is calculated assuming the fresh cement paste as a multiphasematerial. This model enables to take account of the material chemical evolution. The second modelling approach is based on the theory of heat and mass transfer in non-saturated porousmedia. It enables to take account of two main phenomena observed during the hydration of cement-basedmaterials. The first one is the creation of an internal porosity, partially saturated; the second one is thetemperature elevation of the material, due to the exothermic character of hydration reactions.The results of this second modelling seem to fit better to our experimental results