Pet coke (PC) and sewage sludge (SS) have been separately used as admixtures into clayey raw materials for ceramic manufacturing by extrusion and sintering. Thermal analysis of the clay mixtures incorporating 6% of either PC or SS shows a significant shift of the solidification temperature to lower temperatures. The bending strength-in terms of modulus of rupture (MOR)-of the ceramic specimens produced does not change appreciably up to 6% content in PC or SS, indicating that the manufactured clay-based ceramics are able to tolerate low percentages of these admixtures. The specimen open porosity increases and the thermal conductivity decreases by increasing the admixture percentage, while both thermal conductivity and MOR increase with increasing sintering temperature. The results indicate that the utilization of PC and SS in ceramic manufacturing processes may lead to changes in processing parameters, to energy savings and to materials with improved thermal insulating properties.

Keywords: Clay minerals, Secondary resources, Pet coke, Sewage sludge, Recycling, Ceramic manufacturing, Mechanical strength, Thermal insulation.