DENSIFICATION, SHRINKAGE AND STRENGTH DEVELOPMENT IN SELECTED COAL ASHES

The densification process was measured in four amorphous coal ashes, a s a function of temperature at constant time and as a function of time at constant temperature. Densification increased significantly if sam ples were sintered above the characteristic temperature T-cr. Above th at temperature the sintering process is governed by the shrinkage of p ores and the flow of melts out of the inter-granular spaces into the l arge and small pores. The characteristic temperature of sintering is d efined as the temperature at which the sintering mechanism changes fro m the formation of necks and pores into pore-shrinkage and pore-fillin g by melt, which corresponds to low-strength deposits that respond to the pressure created by soot-blowing.