Production of Expanded Clay Pellets by Using Non-selfbloating Clay, Lakes Sapropel and Glycerol

The objective of this study is to investigate the utilization potential of several organic residues and poorly self-bloating (coefficient of bloating K(p) = 2-2.5) and not self-bloating (K(p) < 2) clays, for the production of lightweight aggregates. The following waste materials were investigated: sapropel, sawdust, and biodiesel production by-product - glycerol. The insulation capacity of pellet increases with the increasing porosity of the clay structure. Combustible, organic types of pore-forming additives are most frequently used for this purpose. For this reason, increasing amounts of organic residues (0 %, 1 %, 2 %, 3 %, 5 %, 7 % and 10 % in wt.) were mixed with clay. The pellets were prepared by mixing together finely ground clay with one or both of the selected foaming agents. The pellets were then fired at different temperatures in range from 1090 degrees C to 1170 degrees C until the semi-melt temperature of the specimens was attained. Effects on pellet bloating, water capacity were investigated. The investigated organic waste materials were found to be effective for pore-forming in the clay structure. Their utilization is environmentally safe process. On the basis of the experimental results it is determined that the content of sapropel additive should not exceed 5 %, the recommendable content of glycerol additive is 1 %-3 %, and the optimum sawdust additive amount is 3 %. The water capacity of the specimens with the recommended amount of additives fired at different temperature did not exceed 15 %.