Thermal and moisture coupling performances of poplar fiber inorganic humidity control brick

Abstract

• Three-dimensional thermal moisture coupling model of brick was established. • Mass diffusion coefficients were calculated using X-ray transmission techniques. • The thermal diffusivity was positively correlated with the mass diffusivity. • The compressive strength and color change of absorption were experimentally studied. Wood-inorganic composite building materials are an excellent choice for humidity control. This paper uses poplar fiber and calcium hydroxide to hot-press wood inorganic humidity control bricks. A three-dimensional thermal moisture coupling model of biomass bricks is established to predict the hygrothermal behavior. X-ray transmission technology is used to determine mass diffusivity. It is positively correlated with heat diffusivity. The calculated and experimental thermal conductivity values are lower than 0.12 W/(m·K). The biomass bricks can maintain an excellent thermal insulation effect when absorbing moisture. The compressive strength decreases with relative humidity. After 97.4 %RH moisture absorption balance, the compressive strength is 8.03 MPa, which also met the strength requirements of indoor partition walls. The color difference of biomass bricks after 11.3 %RH moisture absorption is more significant than 3.0, which the human eyes can recognize. Moreover, the moisture content of biomass bricks can be estimated according to the change of color difference. The research is better for providing a theoretical basis and technical guidance for the market promotion of humidity control materials and building energy conservation.