Influence of class C fly ash on the properties of plastic clay and a fired brick body

Abstract

Class C fly ash (CCFA) was used, according to ASTM C618-12a, as an admixture (10 %/w) in calcareous brick clay to determine the difference (in comparison with pure clay) in the clay body plasticity (CCFA increases the water content, decreases the drying shrinkage, drying sensitivity and bulk density of a green body) and in the properties of a fired body (since CCFA acts as a pore-forming agent, we can expect a lower bulk density and better thermal insulation). Due to low firing temperatures of the brick body (850 °C and 1000 °C), there is no risk of an anhydrite decomposition as Class C fly ash does not increase the SO2 content in flue gas during the firing and efflorescence.