Lime spalls and efflorescence from lime and gypsum on heavy clay products
This paper provides an overview of the properties and effects of carbonate and gypsum components that are frequently included in raw materials for clay bricks and roofing tiles. Their behaviour in drying and firing is shown together with the anticipated effects on the fired bricks and roofing tiles as well as methods to avoid undesirable damage such as spalls and efflorescence.
1 Introduction
The paper is based on the activities in the laboratory of the company Lingl. During daily work it became apparent that there were often difficulties arising from the different common names and chemical reactions and that a short recapitulative description was lacking.
2 Lime, Dolomite
2.1 Carbonate basics
Lime (calcite) and dolomite are carbonate minerals and inorganic salts respectively of carbon dioxide. They are hardly soluble in water. During the dissolving process the cations Ca2+ or Mg2+ as well as the carbonate anion CO32- are produced. Originating from either dissolving...
