Hygrothermal properties of rice husk concrete: field study (in situ) and laboratory investigation

To reduce the building sector's contribution to overall energy consumption, particularly in West African countries where it accounts for more than 50%, this study explores the hygrothermal performance of rice husk concrete (RHC). Experimental approach based on laboratory tests were carried out to assess several properties of RHC, including bulk density, thermal conductivity, specific heat capacity, thermal diffusivity, moisture sorption-desorption, water vapor permeability, and the moisture buffer value (MBV). In addition, an RHC building was instrumented and monitored to assess its hygrothermal behavior. Sensors have been judiciously placed to collect the environmental variables of temperature and humidity on an hourly basis over a 6-week period (July–August 2024). This data collection allowed the determination of the thermal time lag and damping factor of RHC hollow block walls. The results demonstrate an average bulk density of 818 kg/m³, thermal conductivity of 0.16 W/(m·K), specific heat capacity of 1417.35 J/(kg·K), thermal diffusivity of 0.176 mm2/s, vapor permeability of 2.44 × 10–11 kg/(m·s·Pa), and an MBV of 3.27 g/(m2·%RH). The material also contributes to reducing indoor temperature fluctuations, with an average damping factor of 0.6 and an average thermal time lag of 2 h. These properties make RHC an excellent moisture regulator reinforcing its potential as a sustainable building material.