Physicochemical effect of the aeration rate on bloating characterizations of artificial lightweight aggregate

This study investigated the effect of the aeration rate of molded pellets on the physical and chemical bloating mechanisms of artificial lightweight aggregate materials. Samples were prepared by mixing acid clay as a raw material with Fe₂O₃ and carbon. The samples were manufactured by various molding methods, in this case hand molding, uniaxial pressure molding, cold isostatic pressure molding, and extrusion molding. The particle density and pore distribution of the molded pellets were confirmed, and the changes in the properties and bloating activation temperatures of the aggregates were observed. The density of each molded pellet differed according to the molding method, and it was confirmed that molded pellets having a lower aeration rate bloated at a lower temperature. When the pressure from the gas inside is high at a temperature where viscous behavior does not occur, cracks form inside the aggregate. In the samples to which Fe₂O₃ and C were added, the internal viscous behavior did not cause cracking due to due to the formation of black cores. In the molded pellets with low aeration rates, the black core formed at a lower temperature, and the bloat-promoting effect was confirmed.