Mechanical and thermal properties of sustainable lightweight concrete containing raw buckwheat husk

The increasing amount of industrial and agricultural wastes poses a serious challenge to the global environment. Using these wastes to produce construction materials will help to protect the environment and promote sustainable development. In this paper, a sustainable lightweight concrete with raw buckwheat husk (BH) as aggregate and fly ash (FA) as part of the binder was prepared. Mechanical properties (such as compressive strength and flexural behavior) and physical properties (including porosity, water absorption, density and thermal conductivity) of buckwheat husk concrete (BHC) were investigated. The effect of the content of buckwheat husk and the ratio of fly ash to binder material on the properties of concrete were evaluated. The experimental results show that it is feasible to produce lightweight concrete by utilizing buckwheat husk and fly ash. As the main purpose of BHC is for nonbearing and thermal insulation walls, the primary properties considered are thermal conductivity and lightweight. Although addition of buckwheat husk reduces mechanical strength, the strength is within the acceptable range (5–27 MPa). Incorporation of buckwheat husk has provided a positive effect of decreasing the density and thermal conductivity. Desirable BHC with FA/binder of 0.3 and BH/binder mass ratio being 15% obtained compressive strength (16.48 MPa), thermal conductivity (0.68 W/mK) and density (1562 kg/m 3 ). The finding of this paper provides a way to produce sustainable construction materials from agricultural waste.