Porosing agents in the Austrian brick industry

In this report, the Federal Environment Agency describes the origin and use of porosizing agents in the Austrian brick industry. These additives are added to the raw clay and leave fine air pores during firing, which provide better heat insulation of the brick. In 2005, 109,733 tonnes of paper-catch materials, 35,811 tonnes of sawdust and smaller quantities of sunflower-shells, polystyrene and lignite were used as porosizing agents. In addition to the list of porosifying agents that are currently used internationally, production waste and its possible recovery are also shown. The report also describes how conventional porosifying agents can be replaced by organic substances (e.g. plant fibres or sewage sludge) or inorganic substances (e.g. diatomaceous earth or coal ash).