Impact of the determination of the sorption-desorption curves on the prediction of the hemp concrete hygrothermal behaviour

Hemp concrete is a sustainable material with low embodied energy. However, its development as a building material requires a better evaluation of its moisture-thermal buffering abilities behavior, which are known to strongly depend on the amount of water contained in wall pores and its evolution. In this context, the aim of this paper is to study the experimental determination of sorption-desorption curves of hemp concretes following two methods and at two temperatures (23 °C and 40 °C). The former considers the total sorption-desorption loop, from the dried state to a relative humidity of 85%, while the second one is based on partial relative humidity cycles between 23% and 85%. At first, the difference between the curves obtained through these two methods were analysed. They were then implemented in a simple hygrothermal model to simulate dynamic hygroscopic and hygrothermal loadings. The comparison between the theoretical calculations and the experimental results eventually allows to scan which of these relations is more representative of the real dynamic behaviour of the tested hemp concretes.