Mass gain due to the chemical recombination of water in fired clay brick

Mass gain due to recombination of water in freshly fired brick ceramic is compared with that in both bulk and powdered samples of the same material following reheating to 500°C. In all cases the gain in mass occurs in two distinct stages both linear with (time)1/4, the first (Stage I) ending at t∼1.5 h followed by a second stage (Stage II), which continues indefinitely. The powdered ceramic following reheating shows a dramatic increase in reactivity with a mass gain in the first stage equivalent to that which would be achieved by the bulk ceramic in over 2000 years. © 2008 The American Ceramic Society.