Experimental and Theoretical Study of Adsorption/Desorption Isotherms of Straw Earth Material Used in the Construction of Shell Huts in the Far North of Cameroon

Earth-based materials (EBM) provides a valuable avenue for improving thermal comfort, energy consumption, indoor air quality and humidity regulation. However, in the literature, very few studies have addressed hygrometric characteristics of shell huts in EBM from the far north region of Cameroon. The use EBM is hampered by the non-availability of databases related to their intrinsic properties and through unfamiliarity of their behavior over time. In the meantime, these shell huts in EBM are known for their moisture which regulates properties and thus contributes to the comfort of their occupants. This study aims to determine experimentally the adsorption/desorption isotherms at 30, 40 and 50 °C of the straw earth material carried out by the static gravimetric method for eight saturated salt solutions (LiCl, MgCl2, Mg(NO3)2, NaBr, IK, NaCl, KCl and K2SO4). The experimental curves obtained for absorption / desorption show that for a given water activity, the equilibrium water content Weq increases inversely with temperature (i.e. decreases with increasing temperature, and vice versa). In addition, the absorption curve does not overlap with the desorption curve. As a result, these shell huts in EBM display interesting humidity regulation characteristics.