Utilization of Charcoal from Wood Waste I. Properties of charcoal-cement composite boards

Charcoal obtained from wood－based waste materials is of low quality with amorphous shape and low density. With the aim of utilizing this low-quality charcoal, the properties of charcoal-cement composite board were investigated. Pulverized Sugi wood charcoal, Portland cement and water were mixed and then set and hardened in a mold. Thirteen types of mixture ratios of charcoal to cement were used to produce 10mm-thick composite boards. The flexural strength of the board showed the maximum at the charcoal/cement mix ratio of 0.05 and then decreased as the mix ratio increased. The distinctive features of the composite board are a high water-sorption and a considerably high capacity of moisture sorption and desorption. The increase in the amount of charcoal brought about the increase in the water absorption. Although the boards absorbed great amounts of water, dimensional changes were very small. The capacity of adsorption and desorption of moisture increased with the increase in the amount of charcoal and reached the maximum value around the charcoal/cement mix ratio of 0.3, and then decreased. These characteristics suggest the possibility of applying the board to the interior walls and the roof-cooler of buildings