2009 Volume 4 Issue 1 Pages 91-98
During the three stages of production, construction and demolition, approximately 1.5 million tons of waste plasterboard was generated in 2007. Bassanite is produced by heating gypsum obtained from waste plasterboard, under conditions of 130°C or more.
Engineering properties make bassanite obtained from waste plasterboard useful as an improver for soft soils. However, fluorine contents may exceed the approved value in the Japanese environmental quality standard. We have to investigate, therefore, reduction in the solubility or mobility of fluorine, physically and chemically. To overcome this, we developed a solidification technology for fluorine contaminated Bassanite using Portland blast-furnace (B) cement. The concentration of fluorine decreases with increasing curing time and bassanite content. The concentration of fluorine after treatment using Portland blast-furnace (B) cement became lower than the Japanese environmental quality standard value.
