Recycle of waste glass into "glass-ceramic stoneware"

The reuse of soda-lime-silica scrap or waste glasses as additives for traditional ceramics has been investigated extensively in the literature. Although interesting, this solution does not generally allow large quantities of glass to be recycled. This study reports a novel high glass recycle approach that replaces, in the formulation of porcelain stoneware, the feldspar flux with finely powdered glass derived from the melting of different waste products, e.g. lime from fume abatement systems, feldspar mining residues, and scrap soda-lime glass. At an optimized glass/clay ratio, the "glass-ceramic stoneware" samples sinter at 1000 degrees C. The "glass-ceramic stoneware" has a bending strength approaching 90 MPa and a fracture toughness exceeding 2.0 MPa.m(0.5), similar to those of conventional porcelain stoneware, which requires sintering at higher temperatures. The high strength and fracture toughness are attributed to the interaction between the glass and clay residues upon sintering, which allows the development of several different crystalline phases.